Hydrating for 100k - how to minimise weight & time lost??? [Archive]

drasnian

01-10-2008, 09:00 AM

How do you stay hydrated enough during a 100k race without either:

- lumping kilos of dead weight on your back plus a bottle to refill as
needed, OR
- taking several bottles and wasting time refilling them at least once?

In both 100k events I've done this year, I took my 3L Lobo and a bottle. At Mogo, my legend of a brother served as roadie chick, handing me a sustagen as I went through the 31k feed station, and topped up my bottle for me at 50k. In hindsight, maybe I could've done without a hydration pack for this race. I heard the top guys took 2 bottles and exchanged them for full ones at halfway. That sounds ok for 4:40min when it's cool, but what if you're on the slow side of 5:30?

The Dirtworks course is faster ---> less water needed. But it's also pretty remote, and you couldn't be in touch with your trusty road crew until the bottom of Shepherds Gully at about 65k. If you were riding in about 15th-20th place, it'd be getting on towards 3 hours, by which time most would easily have emptied 3 bottles. [Is it possible to carry a 3rd bottle behind the seat? Hmmm.]

Soooo.........how does one avoid lugging a hefty amount of water on your back up massive climbs in the first 50k of an enduro, without losing just as much time as you'd have saved in not carrying a pack while you trickle water into several bottles at feed stations? Or should I just shut up and cop a time penalty either way?

Would it be better to carry 2 bottles and refill them both 3 times (i.e. at every drink station) or carry 3 bottles and refill them all once at 50k?

Not having to carry a pack sounds nice. Slightly less weight overall, NO weight on your back, cooler ---> sweat less etc. Perhaps carrying 3 bottles is just as much a pain in the butt (?)

Thoughts please!

leftieant

01-10-2008, 09:28 AM

I think trick #1 is to hydrate properly beforehand - I find this makes a huge difference to how much water I drink. Proper pre-ride hydration can make the difference between me drinking 1/2 bottle on a 2hr ride, and drinking 2 bottles and still being thirsty.

The longer races, I just suck it up and carry a pack with 2 litres of water, plus 2 bottles of strong Enervit. Usually one bottle is gone by the 50km mark (if it isn't I make a point of drinking it before I continue), which then gets refilled with water. First aid kits etc can get jammed in the pack also then.

If you've got deeper jersey pockets, you might be able to jam a smaller bottle in there, and potentially ditch a pack.

jmcavoy

01-10-2008, 10:31 AM

For multi lap races I only use bottles, more for freedom and comfort than speed. For 100k marathons I chuck on a 2-3L camel back (and pre hydrate as Leftieant points out), as stopping for anything (like refilling) just aint an option.

Do you really think that extra 2-3kg is making a big difference to your race time? It would be worthwhile doing some time trial climbs with a pack on and without and seeing if there was any difference... I'd love to hear the results if you do, because to be honest, I doubt there will be any difference, but I have not done the tests and am purely speculating.

I also note I am way off coming 15-20th like you, and it is possible at the pointy end that if a camel back costs you 1 minute of race time, it costs you a race placing, although how long is a refill stop costing you? (not just in stopped time, but in dropping off the bunch, getting up to speed again, fatigue induced from stopping).

I just checked the dirtworks results for this year and find that in the top 23 placings, the average race time difference is 2.17mins, so if the camel back costs you more than 2.17 mins, you will loose a place, but I am wondering will the pack slow you down more than refilling bottles (which I guess is the whole point of this thread right? You're wondering the same thing). I'd also speculate that losing one place if you're coming 20th is really no big deal, 20th or 21st? Who cares, what's the diff? ;) Difference between 4th and 3rd, well, now every second counts!

It is interesting to contemplate, so if anyone has done any time testing of this stuff I'd love to hear!

I was planning on doing some time trialling at Stromlo tomorrow for the Scott, 4 runs up the red lap climb, so I might chuck a full 3L pack on for 2 runs and do 2 runs without a pack and answer my own question... I'll post the results up tomorrow...

DaGonz

01-10-2008, 10:48 AM

Soooo.........how does one avoid lugging a hefty amount of water on your back up massive climbs in the first 50k of an enduro, without losing just as much time as you'd have saved in not carrying a pack while you trickle water into several bottles at feed stations? Or should I just shut up and cop a time penalty either way?

....

Thoughts please!

Suck it up and cop the time penalty either way. Carrying water is something you don't want to skimp on unless you know you can get away with it, especially in a 100k where stops between stations can be long.

Personally, I take a 1.5l camel back and a 750ml bottle. For the highland fling last year we had the benefit of the "mile high club" and I'd left bottles there, but still refilled my camel back when I could. I've made the mistake of skipping water stations before and it cost more than the couple of minutes to refill...

If you really want to minimise time, most of your faffing time at water stations is queuing and general faffing, pulling bladders out, unscrewing lids etc. The trickle time for water is going to be the same if you're filling one bladder or 3 bottles. Unless you have support crew, I would suggest you minimise your water stops rather than minimise your water.

The weight penalty going up should be repaid in kinetic energy at the bottom, and I think the cost of carrying the extra kilos (without being silly) is not as much as you might think[1].

*shrug*

Cheers
Gonz

[1] I just did the sums, and I think 2 extra kilos for an 80kg rider+bike equates to 45secs over a 300m high/30 min climb

DaGonz

01-10-2008, 12:23 PM

I just checked the dirtworks results for this year and find that in the top 23 placings, the average race time difference is 2.17mins, so if the camel back costs you more than 2.17 mins, you will loose a place, but I am wondering will the pack slow you down more than refilling bottles (which I guess is the whole point of this thread right? You're wondering the same thing). I'd also speculate that losing one place if you're coming 20th is really no big deal, 20th or 21st? Who cares, what's the diff? ;) Difference between 4th and 3rd, well, now every second counts!

I think you need to ensure you're going to have enough water to get you between known water stations as a first priority. For most 100k races I've been in, that'll mean you'll either have to decide between a one stop or two stop strategy. That'll probably decide *how much* water you need to carry. Sure there's often smaller stops along the way but you don't know necessarily where they are so you can't really plan on filling up whenever you're empty.

If it's a two or more stop strategy, then this discussion becomes perhaps a little more relevant.

Generally though, I would have thought the act of carrying or filling up camel backs etc... a mutual cost between all riders of a similar speed and that most people are simply carrying enough water to get them between the major known water stops.

Cheers
Gonz

...jim

01-10-2008, 01:43 PM

I've always figured 50km or ~3hrs is too soon. I'm used to riding for 3-4 hrs casually with a 3L pack on - and with proper prehydration and some additional liquid, it's too soon. I've also always figured that I'll be quicker if I stop less. Stopping, finding the water, queueing, filling, pulling your pack apart, etc... takes a long time.

As a reasonably mid-pack plodder (in what feels like a previous life) in 100km or Polaris events I'd usually budget on a 3L bladder full of water, and a bottle of energy drink - with powder to mix up another one. Then I'd be aiming at about 2/3 distance before refilliing. ('fling: Wingelo the second time - DW: cp/2 - Coffs: 65km mark - Polairs: 'bout 5 hours [or where there's water]).

Refilling is mixing up new stuff (quick - pack stays on) and only attacking the bladder if it was hot enough for me to be close to draining it... more common in a 7hr Polaris.

SteppenW

01-10-2008, 05:56 PM

I'm mid-field too (lucky if I can pull off a marathon in 6hr even when I'm trying). Anyway, they're more of a training exercise than a must-win for me.

My hydration begins at least 2 days out. A little bit more salt too, so that the water can be retained.

I usually carry an extra-strong mix in a bottle and a small hydration pack (with another mix ready to add to the bottle at half-way). The pack is handy for all the other crap you might want to bring along (clothes, tools, tube, patches, extra food).

How much water I actually carry in the hydration pack depends on the weather. Maybe 2l if it's hot; 1l if it's cold.

Frequency of stops depends too. I'm happy to top up the bottle with plain water if necessary (takes no more than 30 seconds). Refilling a bladder can take another minute.

You're probably better off carrying too much water initially. Your performance will really suffer if you start to dehydrate. You need water to eat too - if you don't eat you'll really suffer. If you find yourself finishing with an excess of water - just dump it.

bazza

01-10-2008, 06:12 PM

its going to depend on your bike as well. i love racing my hardtail because i can fit 2x water bottles = 2l of water on board no problem. magnum water bottles rule. super fast to refil and hold 1l. i did a race with a camelback this year because i was on a duallie and it was fantastic! i wrote off packs for a long time but really enjoyed it! i think i had this discussion with another far far more experienced hardtail rider and they said they would run 2l on their back than on their bike because of the handling in any situation. was that you Da Gonz?

spikenet

02-10-2008, 10:38 AM

I'd have to agree camelbacks are much easier to handle. I went to bottles for XC racing but found it nearly impossible to get a drink in so switched back. Probly not as big an issue for longer enduro things, plus all the other crap you need to carry like spares and food etc. I like the idea of water in camelback and gatorade in bottle on the bike.

jmcavoy

02-10-2008, 05:51 PM

I was planning on doing some time trialling at Stromlo tomorrow for the Scott, 4 runs up the red lap climb, so I might chuck a full 3L pack on for 2 runs and do 2 runs without a pack and answer my own question... I'll post the results up tomorrow...

I did indeed goto Stromlo today and did 4 time trial climbs up the red lap climb (bottom to summit, so the test is all climbing); I did them all without a camel back, my aim this week was to get a baseline to see what variance there was without anything changing (like adding a pack to my back). The results:

Time | Avg HR
18:03| 157bpm
18:12 | 156bpm
17:56 | 156bpm
17:51 | 157bpm

So the variance with no change was +/- 10.5 seconds or +/- 1%. Multiply that out over a 4 hour marathon and the variance is +/- 2:21 seconds. So I think that's a fairly stable baseline to test against. I'll repeat the time trials next week, 2 without 3L pack, 2 with one and we'll see what the variance is... will the pack affect me? I dunno, should be interesting.

I also timed refilling a single water bottle (from the Stromolo water tap), 61 seconds counting pull up, refill and back on the bike, with no queue.

I'll update next week...

DaGonz

02-10-2008, 06:38 PM

I'll repeat the time trials next week, 2 without 3L pack, 2 with one and we'll see what the variance is... will the pack affect me? I dunno, should be interesting.

3kg's? 'sif, your legs a huge!! ;)

What's the elevation gain on those? and do you know how much you & your bike weighs? I'll see if I can't guess the time difference

Cheers
Gonz

ACNRS

02-10-2008, 09:04 PM

at most(of not all) of the 100k races have a food/drink station every 25-30km. i took one bottle and just got it refilled at each feed station.

drasnian

03-10-2008, 07:43 AM

I did indeed goto Stromlo today and did 4 time trial climbs up the red lap climb...The results:

Time | Avg HR
18:03| 157bpm
18:12 | 156bpm
17:56 | 156bpm
17:51 | 157bpm

Good work boy. Very consistent set of reps there, too! If you do it again next week, in similar conditions, but with 3L on board, I'd guess...average 20-30 seconds slower at a similar heart rate. I wonder if you'll feel like you should be in a certain gear, and so you'll work a bit harder to avoid shifting down, but then pay for it a little in your last 2 reps??

Looking forward to the results!

drasnian

03-10-2008, 08:17 AM

I also note I am way off coming 15-20th like you, and it is possible at the pointy end that if a camel back costs you 1 minute of race time, it costs you a race placing...

I haven't finished that high up in a race yet either. If I come 20th in my next 100k event (hopefully Dirtworks '09) I'll be happy. My first ever bike race was Dirtworks this year, where I came 40th.

I dream of hanging it out at the pointy end of the field!

jmcavoy

03-10-2008, 10:06 AM

3kg's? 'sif, your legs a huge!! ;)

What's the elevation gain on those? and do you know how much you & your bike weighs? I'll see if I can't guess the time difference

Cheers
Gonz

Most of the guys at the gym have bigger arms than my tooth pick legs :D

The polar says the climb for each of those reps is 150m each.

I got all the same gear back on (crikey does it smell today :D), jersey, nicks, shoes, 3 gus, some sports beans and my mobile phone in the pockets, helmet gloves, and a full water bottle on the bike and I got 85.6kg on my scales.

The bottle is 698grams full, and the 3L camel back 3568grams, so if I ditched the bottle and used the camel back instead, the total weight gain will be 2870grams, or another way to say it would be: "bottle boy weighs 85.6kg, bladder man weighs 88.5kg, over the 150vm climb (3% grade btw as the distance is 5km).... what will the time difference be?"

I look forward to your calculated prediction.... perhaps a little wager is in order ;) hehe

In my last post I said if I multiplied that climb out to be 4hrs it might be comparable to what difference you get with a camel back on at a 100k race, but that's not entirely true, because no marathon I've done is all climbing for the entire race (although the Otways sure felt like it! :)) and the added weight shouldn't affect me much at all on the flats and it should help me on the downs. The dirtworks for example has 1660vm in it (from my Polar), so my little Stromlo climb is about 10% of the dirtworks climb, maybe it would be more accurate to take that +/- 10secs and times by 10 to get a difference of +/- 1:40, not 2:21. That would be more accurate I think, and it shows I can get fairly consistant (+/- 0.7%) reps in and the test next week should be valid.

Anyway, a good rest for the next 6 days and I'll have another go the same fresh legs and we'll see what happens, I'm certainly curious...

jmcavoy

03-10-2008, 10:11 AM

I haven't finished that high up in a race yet either. If I come 20th in my next 100k event (hopefully Dirtworks '09) I'll be happy. My first ever bike race was Dirtworks this year, where I came 40th.

I dream of hanging it out at the pointy end of the field!

Well you flogged me, I came 63rd, so you put a solid 12 minutes into me (bastard ;)) and you got Spoonboy by 2 places, or 1 minute. Well done, a top effort for your first ever race, crikey, a very impressive result!

JD26

03-10-2008, 10:46 AM

Fellas
Michelle Ferrari (yes the guy that helped Lance Armstrong 'prepare' for the TDF) has worked all this out scientifically for you as a component of the bike.

"Five hundred grams saved on the weight of the chassis and non-moving parts translate into an advantage of about 30” for every hour of climb; an even more determinant factor is the weight of wheels, crankset and pedals: every 100 grams saved correspond to an average gain of 20” per hour of climb.
The rotational inertia of the crankset, wheels, and pedals resists every angular acceleration of these same moving parts, with an added energy cost depending on their mass. " www.53x12.com

So if you are carrying 3kilos extra on your body ((be it fat, muscle, camelbak etc) then you are looking at close to a minute over every hour of climbing.

That probably doesn't take into account the "accumulated fatigue" you will experience over a long period of time as you push around that heavier weight - this is where the muscular endurance comes into play.

The concept I am trying to get across here is given as an example below.
How many repetitions to failure of a leg press machine could you do with 100kgs.
How many repetitions to failure of a leg press machine could you do with 103kgs.

Another issue with the camelbak (ie weight on the back up high) is the centre of gravity is raised. This may or may not affect handling.

However, the coordination taken to drink from a bottle is not always the easiest (especially in singletrack).

But at the end of the day - you just have to go with what you are comfortable with and what you think will work best for you.

jmcavoy

03-10-2008, 11:06 AM

So if you are carrying 3kilos extra on your body ((be it fat, muscle, camelbak etc) then you are looking at close to a minute over every hour of climbing.

So, to postulate, based on those numbers, will the extra weight affect your race placing if you are in the Top 20 of a 100k marathon? I'd say no. If you are climbing for 2 hours, you'll loose 2 mins, but refilling 2 water bottles will take 2 minutes (with zero queueing, add some time to that number if there are other people filling up), so best case, you're pretty much even.

Even you were climbing for the full 4hrs (Otways style ;)), that's 4 minutes you'll loose withthe camel back on, now take off the 2 minutes for bottle refills and that's a time difference of 2 minutes, which is inside the 2.17 minute difference between riders.

So that theory says it will not affect you by a single race position.

PS: JD26 are you sure your maths is right? every 500g costs 30" per hour, that means for 3kg extra you would lose 3 minutes, not one minute. That's 6 minutes over 2 hours of climbing and now we're talking about 1-2 race positions lost.... hmmm, maybe there is something in this after all...

I'll still do a practical test next week as I am curious and a 'I need to see it to believe it' type of guy...

Ozchuck

03-10-2008, 11:36 AM

Hmm... you're forgetting that as you go, weight of the camelbak will also reduce.if you're refilling 3 times, when you start you'll only be 2 kilos over the weight of the bottle, and when you get to the 1/3rd way mark you'll be one kilo over, and then in the last third it will be even.

I prefer camelback to bottles on a MTB, keeping that hand on the bars is sometimes very healthy for you, haha.

jmcavoy

03-10-2008, 11:53 AM

Hmm... you're forgetting that as you go, weight of the camelbak will also reduce.

Fair call, as the camelback gets ingested, you're carrying less weight (compared to bottles). Based on one bottle refill stop, with two bottles (which equates to 3L of water in either the camel back or the bottles for the entire event); the first half of the race has the camel back costing you 2kg extra over two bottles and in the second half, only 500grams extra (because the camel back, well mine anyway, weighs ~500g and it will be carrying the eqivalent of two water bottles of water).

Take that and apply it to the 30" lost per 500g and guesstimate an hour and a half of climbing in the first half and an hour and a half climbing in the second half (which is what my Polar tells me I did at the last dirtworks) and we get 2 minutes in the first half and 45secs in the 2nd half, a total camel back cost of 2:45, now the bottle refill will be 2 minutes without queung, so the cost is actually 45 sseconds.

If there's a queue, the the bottle boy is gonna loose, and even if there's not a queue, 45 seconds is not enough of a difference to gain or lose a single race position.

This is fun to theorise about :)

JD26

03-10-2008, 12:47 PM

I agree with all the arguments for and against. You will lose weight from the camelback as you go. The weight goes into your body. But then you sweat it out (or breathe it out as condensation).

When I race XC - I only use a 500ml bidon, and pick up a fresh one each lap. Does it make a difference - depends how much pure climbing there is, and how steep it is. Is anything less than 30 seconds per hour important to me - Yes. Over 2 hours this may decide the podium positions.

For a 4-5 hour race - it is better to be hydrated enough rather than worry about saving weight. Either, you take it all for the entire ride, or you stop and fill up. The net result probably would be close to nothing.

I think that when you are racing short lap arrangements or have the luxury of a team car - then by all means, go super light and minimalistic.

For 100k you would need to know if they have a transition/feeding section where you are not timed (a la Highland Fling) - IF this was me - I would go the bottle.

I would probably go the bottle anyway,:) as I can track my fluid intake a bit better ( I am a 'sweater' and know how much I lose per hour, which in turn drives what I need to intake per hour)

DaGonz

03-10-2008, 01:14 PM

PS: JD26 are you sure your maths is right? every 500g costs 30" per hour, that means for 3kg extra you would lose 3 minutes, not one minute. That's 6 minutes over 2 hours of climbing and now we're talking about 1-2 race positions lost.... hmmm, maybe there is something in this after all...

I'm not sure either maths is right... but going on your numbers.

you took say 18mins flat to lift 85.6kgs up 150m's. how long would it take to lift 88.5kgs? well basically you're adding energy to the system over a time frame, to which we can guestimate a "Power" rating (work done on time) Assuming that's the amount of power you can put out then the heavier person has to do more work at a slower rate. so if P = W/T then W1/T1 = W2/T2 or

85.6*10*150 / 18mins = 88.5 * 10 *150 / T2

or

88.5/85.6 * 1080secs = T2 (a whole bunch of stuff cancels out)

T2 = 1116 secs, or I reckon it'll take an extra 36secs for our dear guinea pig to climb with his 3L camel back

Now in reality, that 18mins of the red lap climb has some flat and some descent to it, to which the weight has little, or at least different effects, so we'd need to add a bit of fudge factor on that, along with all the other fudge factors.

But I'd say in a perfect world, an extra 500mls would cost Jason 21secs over an hour climb.

Looking at the whole water stop situation. Everyone seems to agree that you need to make at least one water stop during the race. The flow rate of water isn't going to change if you stop to fill 1 x 1L bottle 3 times or 1x3L camelback once and it's really all the faffing around and stopping that costs when filling things up.

I still think your priority is going to be making sure you have enough water to make it between a major checkpoints and it's going to be that and not some other strategy that will dictate what you do. The fling makes it easier for you, you get a 5min allowance for the train which if you're wise and only a little bit lucky then you can make good use of twice! the risk is getting dropped by whatever bunch you're with.

*shrug*

Cheers
Gonz

spikenet

03-10-2008, 01:28 PM

Fellas
So if you are carrying 3kilos extra on your body ((be it fat, muscle, camelbak etc) then you are looking at close to a minute over every hour of climbing

not a bad estimate, tho I would say it overestimates the loss.

if you want pure maths, I have calculated to ride up a 6% gradient hill at 10km/h on a 12kg bike and body weight of 85kg to use 727 kj/hr and with the extra 3kg of camelback its 749kj/h so an increase of 22kj/h. To maintain the same energy use with the camelback you would need to ride 0.5 km/h slower or 9.5km/h. (I used a free program called BikePower to calc this out)

So given that math solution, your going to loose 1/2 a km every hour when maintaining the same "effort" using a camelback. Timewise thats about 30 seconds.
The caveat, and its a big one is that you will probably be better hydrated. It might not be much but it doesnt take much effort to drink from a camel compared to getting a bottle out and riding one handed.
Also your doing less frequent waterbottle filling and what goes up must come down.. you'll gain extra speed on the downhills :)

cheers.

spikenet

03-10-2008, 01:31 PM

I reckon it'll take an extra 36secs for our dear guinea pig to climb with his 3L camel back

hey gonz.. we came to the same answer, albeit in a different way at the same time.. cool....

drasnian

03-10-2008, 02:24 PM

if you want pure maths, I have calculated to ride up a 6% gradient hill at 10km/h on a 12kg bike and body weight of 85kg to use 727 kj/hr and with the extra 3kg of camelback its 749kj/h so an increase of 22kj/h. To maintain the same energy use with the camelback you would need to ride 0.5 km/h slower or 9.5km/h. (I used a free program called BikePower to calc this out)[QUOTE]

Awesome!

[QUOTE=spikenet;1563810]So given that math solution, your going to loose 1/2 a km every hour when maintaining the same "effort" using a camelback. Timewise thats about 30 seconds.

But bottle boy was going nearly 17km/h in posting his 18:00 time up the 5km track with a gradient of 3%.

Also your doing less frequent waterbottle filling and what goes up must come down.. you'll gain extra speed on the downhills :)

No extra speed. Not unless you're talking big downhills, where wind resistance factors in.

JD26

03-10-2008, 02:36 PM

Sorry guys
I didn't bother with the pure maths when posting my "3kgs and 1 minute". I went on the 'tried and true' field tested experience.

What I did do was really underestimate the time. I have found that there is a bit of difference in climbing times when I have been 3kilos lighter, but I do believe that the major difference is in how well rested and\or well trained I have been plus a slight combination of certain parts.

I have a training run that climbs both Mount Ainslie and Mount Majura starting from my front yard. I have been doing this for about 2 years on average twice a month. I have done it with both my 10 kilo dually and my 9 kilo hardtail. I have also done it to test tyres, and any new parts. Some of the slopes probably approach 20% in places.

My times have come down from about 57 minutes to the latest one in the last 2 weeks to 49:50.

Here is what I know.
1. I have lost a bit of weight over this time. Currently down to 78kgs. 12 months ago I was 83kgs.

2. My form has improved over this time (thank god). I have other 'loops' that I do to measure this - they are 'typical' xc race laps at majura from previous xc club races.

3. I may have also 'dialled' these tracks to within an inch of their top-end speed (for my ability)

4. When I run certain tyres (ie Stan's Crow vs Kenda SB8 vs Maxxis Crossmark) I go faster.

5.Getting the wind right (ie having a tailwind up the steep stuff),

6. Getting the pacing spot on (no point blowing up too early and having to limp it up the second hill)

Each one of these 1%ers has definitely assisted my climbing time. Getting the wind right (ie having a tailwind up the steep stuff), and the pacing spot on are also little 1%ers that give me precious seconds.

Does taking the bottles vs a camelbak make any difference - not for less than an hour - I would run the bottles. If I were to run 3 extra kgs in the camelbak up the 2 climbs I would be slower for sure - I just don't need that much water for that length of ride. I do know that I run out of available water (from bottles) at about 1 and a half hours.

So then that takes about 30-45 seconds to fill 2 bottles, which will sort me for another 90 minutes. I would still have to fill the camelbak up at the 2:15-2:30 mark and that would take the same timeframe. However, you are still carrying extra weight of the pack.

One thing I do know - not having enough water is pretty dangerous, havign a 5% drop in performance due to dehydration is not going to be faster over the long run.

http://www.analyticcycling.com/WheelsClimb_Page.html - Some science to dispel it all.

drasnian

03-10-2008, 03:20 PM

so if P = W/T then W1/T1 = W2/T2 or

85.6*10*150 / 18mins = 88.5 * 10 *150 / T2

I like your little F=mg in there!

T2 = 1116 secs, or I reckon it'll take an extra 36secs for our dear guinea pig to climb with his 3L camel back

T2= 1116.588... Call it 37 seconds slower! Now factor in that next week it could be a wet, slip slider. And our little pig might have come down with the flu, or be over-tired after a late night watching 24 Solo on DVD...repeatedly. Or he could come into some form next week after putting kays in his legs this weekend, and just smash it up the climb in 17:30 each rep, sherpa pack n all, bleeting like the mule he is.

But I'd say in a perfect world, an extra 500mls would cost Jason 21secs over an hour climb.

Yeah using this T2 value it would be just over 20 seconds (37*60/18/6 = 20.55 secs.)

Looking at the whole water stop situation. Everyone seems to agree that you need to make at least one water stop during the race. The flow rate of water isn't going to change if you stop to fill 1 x 1L bottle 3 times or 1x3L camelback once and it's really all the faffing around and stopping that costs when filling things up.

But if I carry a camelbak, I'd might have the sucker full to begin with and, unless there's lots of climbing early -- although there usually is -- take a full bottle and just do one bottle stop at 75k. That's 4-4.5L of drink depending on bottle size. At Dirtworks, I took 3L on my back plus an empty bottle, with the aim of filling it at 50k and maybe again at 72k. I ended up refilling it at both, but spent way more time on other things (e.g. letting my tyres down at the top of the first ridge, as I was too rushed before the race to set them properly after swapping the slicks and had 'em at about 45psi; and using an entire small can of TF2 during the race on my chain, which kept locking up. Naomi Hansen must have thought I was stalking her! I'd stop...she'd pass me...I'd get back on...pass her...stop...she'd pass me...etc. Would have been no less than 6 times between 15k and 40k. Good times :) )

So maybe I shouldn't be so worried about water stops. Hmmm.

tojo

03-10-2008, 03:24 PM

drasnian

03-10-2008, 03:38 PM

I have a training run that climbs both Mount Ainslie and Mount Majura starting from my front yard. I have been doing this for about 2 years on average twice a month. I have done it with both my 10 kilo dually and my 9 kilo hardtail. I have also done it to test tyres, and any new parts. Some of the slopes probably approach 20% in places....

Brilliant stuff! BTW what 10kg dually do u ride? At that weight it's certainly from the no-love-handles department. I've started my Anthem1 on a diet, but my bathroom scales still say not much under 11.5kg.

One thing I do know - not having enough water is pretty dangerous, havign a 5% drop in performance due to dehydration is not going to be faster over the long run.

My oath.

...jim

03-10-2008, 03:39 PM

you guys crack me up. What a bunch of Farkin nerds you are trying to work out the time it takes! Unless you are in contention for a place i doubt saving a few seconds here or there or even a minute or two will really matter.

You're not exactly wrong - but if you add together a whole lot of little things you can end up with a significant chunk. This can be saving 100gm here and there on your bike - and before you know it your bikes a kg lighter... or this can be going the long way and having one less Tim-tam at lunchtime - and before you know it you've lost a kg.

or this can be fine tuning racecraft - and before you know it you're in front of the guy who beat you last week.

Sure, by itself over a 100km race it ain't gonna buiy you no sheepstation - but add it to line choice, tyre choice, gel choice, taper, rest, yaddayadda and you've got yourself an advantage. Of course it's not important - but that's what you get when to put mountain biking on the interweb.

drasnian

03-10-2008, 03:47 PM

you guys crack me up. What a bunch of Farkin nerds you are trying to work out the time it takes! Unless you are in contention for a place i doubt saving a few seconds here or there or even a minute or two will really matter.

Oh yeah, I spose not. If I lived up in the NT I'd be riding with a freakin shotgun on my back as well. Not negotiable. Wonder how much time I'd lose then....

DaGonz

03-10-2008, 03:57 PM

you guys crack me up. What a bunch of Farkin nerds you are trying to work out the time it takes! Unless you are in contention for a place i doubt saving a few seconds here or there or even a minute or two will really matter.

Well, personally I think that's the point some of us are trying to make. We're talking 30 seconds or a couple of minutes here and there which to most people is hardly worth squabbling over, especially as the Origional Poster pointed out, he wasted so much time doing other things.

And again, whatever you do, it's likely to be a mutual cost for everyone around you. But it's an interesting point and it's fun to drag the maths out so

*shrug*

Cheers
Gonz

spikenet

03-10-2008, 07:51 PM

:) What Gonz just said!

No need to leave the couch to test out this theory :D

jmcavoy

03-10-2008, 09:26 PM

Well, personally I think that's the point some of us are trying to make.

That's it matey, I was trying to say there was going to be no loss in taking the camel back and I was keen to proove it too (as I hate being a speculator, I'm a man of fact). Anyway, it is nerdy, but I am a big nerd :D

72Fury

04-10-2008, 08:24 PM

To maintain the same energy use with the camelback you would need to ride 0.5 km/h slower or 9.5km/h. (I used a free program called BikePower to calc this out)
So given that math solution, your going to loose 1/2 a km every hour when maintaining the same "effort" using a camelback. Timewise thats about 30 seconds.

If you reduce your speed from 10.0km/h to 9.5km/h, doesn't that final 1/2 km equate to an extra 3+ minutes not 30 seconds ?. Or am I having a gumby moment and have it all wrong ?.

krizbike

05-10-2008, 09:02 AM

If you reduce your speed from 10.0km/h to 9.5km/h, doesn't that final 1/2 km equate to an extra 3+ minutes not 30 seconds ?. Or am I having a gumby moment and have it all wrong ?.

You are right - 60/19=3.16mins.
If spikenet was right (1/2km = 30s) then they are averaging 60km/h... Maybe that last 1/2km was all downhill? :)

JD26

07-10-2008, 07:48 AM

:)"you guys crack me up. What a bunch of Farkin nerds you are trying to work out the time it takes! Unless you are in contention for a place i doubt saving a few seconds here or there or even a minute or two will really matter"

That's a fair call. I know a fair few of the posters here and there are a fair few who are in contention for a place in their respective classes at every race they enter. In order to be at the pointy end, a bit of "nerdness" doesn't go astray:D

It is "hard work" trying to figure out all the tricky 1%ers that make a difference. However, if you are a "podium ho" then it is worth it I reckon:rolleyes:

A minute or two could make the difference between the podium and outside of top 10. Whether or not you are using bottles or camelback may or may not have an outcome on this.

I am a bottle user.
Reasons: Lighter, can see how much I am drinking, no extra bag on my back to overheat me.

I do own 2 camelbacks though:)

What does everyone else use and what is your reasoning?

jmcavoy

08-10-2008, 04:28 PM

I did indeed goto Stromlo today and did 4 time trial climbs up the red lap climb (bottom to summit, so the test is all climbing); I did them all without a camel back, my aim this week was to get a baseline to see what variance there was without anything changing (like adding a pack to my back). The results:

Time | Avg HR
18:03| 157bpm
18:12 | 156bpm
17:56 | 156bpm
17:51 | 157bpm

So the variance with no change was +/- 10.5 seconds or +/- 1%. Multiply that out over a 4 hour marathon and the variance is +/- 2:21 seconds. So I think that's a fairly stable baseline to test against.

I also timed refilling a single water bottle (from the Stromolo water tap), 61 seconds counting pull up, refill and back on the bike, with no queue.

So I repeated the test today, two laps with a 3L camel back and no bottle, two with just a bottle. Same bike, same setup, same clothes, same phone and fuelling (Gu's).

Time | Avg HR
17:35 | 158 **camel back, anomoly
18:11 | 156 **camel back
17:45 | 156 *bottle
17:43 | 157 *bottle

Lap 1 is an anomoly IMO, I went out too hard and over did it I think, 17:35 is freaky fast and outside what I would call normal for me, so let's write that lap off as weird. I can't explain the speed, but a couple of extra beats a minute were put in and I must have railed every corner. I'd love to know how I did it that fast personally, because I'd like to repeat that every time I raced there ;) Interestingly it does show that even with the pack on I can do the fastest lap of the set, I just need to work a bit harder and nail the course every time is all :)

Comparing the other 3 laps, I believe it would be safe to say the camel back did indeed cost me 27 seconds, roughly 2.5%. Multiply that out over the 3 hours of climbing at the dirtworks (only because we were talking about the dirtworks and I spent 3hrs climbing there this year), and you get a solid 4.5 minute difference, ofcourse you are multiply out an error there, so this is not an exact science. I'd also like to note that has to be seen as worst possible case, because the pack gets lighter as you drink it, so thepack disadvantage in the 2nd half is negligable, where I have treated it as the same disadvantage for the full 3 hours here.

So 4.5 minutes, take off the 2.5 minute to refill your bottles (assuming no queue) and the camel back has cost you 2 full minutes. Would that equate to a single race position if you were in the top 20.... sadly not (on average the difference is 2.17 minutes between riders), and if you had to queue to refill I'd say camel back boy will be faster than bottle man.

Looks like this has proved the theory true boys... what we suspected is proved out. Nice to know I guess.

Conclusion:

Does the camel back affect race placings? I'd have to say no.
I did indeed slow me down, but not enough (when balanced against refilling) to affect any race possies, even at the pointy end.

I did notice something though, and that is my back got more sore with the pack on, and when I took it off after two laps, I felt foot loose and fancy free, lighter and more manouverable, more comfortable.

It's also worth noting I did do the fastest lap with the pack on, for only 1 beat per minute more... so the camel back boy can be the fastest without that much extra effort.

I'll still do my 100k races (and indeed the 100 mile fling in a few weeks) with my trusty camel back, because I don't stop those wheel spinning for nothing ;)

PS: The improvement in lap time this week is going to be my training working and me getting familiar with the good race lines on the course, so you can't directly compare last weeks times with this weeks as I have improved (yah for that :)).

DaGonz

08-10-2008, 05:08 PM

Looks like this has proved the theory true boys... what we suspected is proved out. Nice to know I guess.

In true mythbusters style, you're now supposed to blow something up :D

Cheers
Gonz

jmcavoy

08-10-2008, 05:33 PM

In true mythbusters style, you're now supposed to blow something up :D

Cheers
Gonz

I'll probably blow myself real good this weekend at the Scott, will that do? :D haha

drasnian

09-10-2008, 10:20 AM

Good session there.

It seems you may be a little fitter this week than last week (your last two reps were about 10 sec faster this week, with identical HR). It would've been interesting to see how you faired doing the bottle laps first, then loading up with the camel for the last 2 reps, when more fatigued.

As you say, extrapolating the 27 seconds to a long race does exaggerate the effect of a camelbak, since its weight decreases over time. You could assume a 1.5kg average weight of water + 690g pack weight (for Lobo) = 2.2kg for duration of race (or 3 hours of climbing). And this is without a bottle.

Compare this to using 2 bottles (750ml each). On a 2-stop strategy (at 25 k and 75k), start with less than 2 full bottles (~1250ml), fill both up at 25k, and another partial fill at 75k. It's feasable to average 600-650ml of water on board over the 100k. This would save more than 1.5kg for the entire duration. (Question: does a 10.5kg bike climb better than a 12kg bike??)

Time spent in queues? Nuh. There won't be a queue at 25k (does anyone stop there inside the top 50 riders?). Last year there was virtually no one else in sight at either 50k or 72k. And it's possible to have a pit in under 40 seconds to fill two screw-top bottles.

Spending less than 90 seconds not peddling, but saving 1.5kg every kilometre sounds fast to me.

JD26

09-10-2008, 10:22 AM

So I repeated the test today, two laps with a 3L camel back and no bottle, two with just a bottle. Same bike, same setup, same clothes, same phone and fuelling (Gu's).

Time | Avg HR
17:35 | 158 **camel back, anomoly
18:11 | 156 **camel back
17:45 | 156 *bottle
17:43 | 157 *bottle

:)).

So I repeated the test today, two laps with a 3L camel back and no bottle, two with just a bottle. Same bike, same setup, same clothes, same phone and fuelling (Gu's).

Time | Avg HR
17:35 | 158 **camel back, anomoly
18:11 | 156 **camel back
17:45 | 156 *bottle
17:43 | 157 *bottle

.

Nice work Jim. Now to just do your head in a bit more......
First lap will always be faster - freshness, adrenaline and all that.
2nd lap is quite often the slowest - recovery from going too hard on the first lap.
Can you please swap the 4 runs to do bottle, bottle, camelbak, camelbak. This would ensure that the runs are given equal billing in the order.

Another question. With 3 kgs on your back, how many times can you "spring" up off the saddle, either for a quick sprint out of the saddle, or for positioning on a downhill, before the legs fatigue?

This may take a while to figure out though!

If you have ever wondered why xc racers tape their tubes and CO2 to the bars, seatpost etc.... I don't know if it makes a difference, I don't do it:D

Just another comment. You say that the pack gets lighter the more you drink - the bottles do also. The time to fill up is a valid issue though. You can pretty much only start with 1.5 litres with bottles (2 x 750mL) if you can fit 2 on your frame. A camelback will have 1-3 litres depending on model.

Another thing is that most dual suspension bikes only have 1 bottle mount. In this case the camelbak is essential rather than an option.

I like your "field based testing" it is the only way to tell if something is going to work. Plus you get some secret training in!

jmcavoy

10-10-2008, 09:06 AM

Nice work Jim. Now to just do your head in a bit more......
First lap will always be faster - freshness, adrenaline and all that.
2nd lap is quite often the slowest - recovery from going too hard on the first lap.
Can you please swap the 4 runs to do bottle, bottle, camelbak, camelbak. This would ensure that the runs are given equal billing in the order.

Ta, but you can call me Jason ;) hehe

Your 2nd lap is slowest theory is proven true in both my sessions (although not so with the first lap is fastest, but I get what you mean); that may just mean that the camel back had even less effect on me (as it was the "lap 2 effect" more than the camel back that slowed me), only adding to the arguement that worrying about that extra 2.5 kilos in the camel back is, well, a weight weenie wank ;)

I'm keen to give your lap order a go though, so have penned it in for Thursday October 23rd (in a fortnight). Next week I'm likely to be fatigued from the Scott, so I'll wait that extra week to get more accurate results, this field based testing is the only way I can think of to prove this stuff out, mostly this stuff is speculated by people, so they go buy light bikes and light this and that, when in the real world, when you test it out, there might be a time difference (and in this case, check out lap 1's time, I was faster when heavier), but it's stuff all compared to other ways to make yourself faster.

Will report back then...

...jim

10-10-2008, 09:18 AM

jmcavoy

10-10-2008, 11:34 AM

Just to throw another spanner in the works - given the whole fatigue/recovery factors above might it therefore be better to carry a heavy camelback early in the race when you have the stamina to do so? Yeah, with lighter bottles you'd likely be more effecient even when chock-full of vim 'n vinigar at the beginning.

Perhaps we're looking at a sliding scale in which best might be to use a bigger weight (camelbak) early while it's easier, then come home using just refilled bottles when any difference might be more acute? Not that I've ever really planned it from an efficiency pov, but that's what I tend to do.

Wouldn't is just be easier to start witht he camel back and finish with it on? I mean if you need 3L of fluid, then there it is in the camel back and as you race along it gets lighter and lighter anyway; why would you swap from camel back to bottles half way unless you needed more than 3L of water?

I doubt you would notice 1kg on your back in that last 50k, a kilo is buger all and as you get closer to the finish she's getting down to 500grams, so they get easier to carry as the race goes on and you get more tired, self regulating they are ;)