10mm ss hub? What chain wheel size?

[rozza]

I am either getting a .243 racing the bsx one or a last rufus by the end of september. I am looking at single speed just wondering what options I have on hubs and chain wheel size set up? I am getting a bmx bottom bracket frame (if that matters) I was thinking of having the smallest gearing I could have. I see around that people say 2:1 ratio is good for street and park (my intended use) so would say 25 12 work fine? or Should I save my money and get bigger chain wheels and ditch the bmx cassette hub idea?

[xero]

all of these will work well

25/9 ..... rather expensive (need a mini driver)
28/11..... a little less expensive( mini driver)
33/13..... even less expensive again(cassette)

[rozza]

So pretty much I take it on mtb you use the same gear ratios as on bmx? As the smallest size on a cassette is 11tooth usually so could I just get a normal mtb cassette hub and just use single speed spacers and have a 28tooth up the front?

[bradh]

The 243s have 135mm x 10mm rear spacing. The rufus is the same. This means you can't use a bmx cassette hub. Well, actually, you could: if you find an old 10mm-axled bmx cassette hub, you could space it out, but it wouldn't be an ideal solution. Alternatively, you could take to your dropouts with a file, open them up to 14mm, and then use a spaced 14mm bmx hub, but that'd probably be an even less desirable solution. In short, you'd certainly be best to get a 135mm x 10mm single-speed mtb cassette hub, which would fit the dropouts correctly — the consequence of this, however, is that no mtb ss hub that I know of is compatible with any of the 1-piece drivers that are available for bmx hubs. So, in all likelihood, the 9t rear and 11t rear options that xero mentioned aren't actually options. (Of course, nor would be a 10t rear, since this would also require a one-piece driver.)

In sum, you'll be restricted to a 12t or larger on the rear. But that's not a bad thing, 'cos anything smaller is pretty unnecessary on an mtb.

If you're going to run 26" wheels, I'd go for something slightly harder than 2:1. I reckon 25:12, as you mentioned, or 27:13 would be good options.

[bradh]

(Just re-read stuff...)


So pretty much I take it on mtb you use the same gear ratios as on bmx?
ah, no.

all of these will work well
Sorry, but, ahhhh, no they won't. Particularly if we're talking about 26" wheels.

[Rik]

Just to be safe, try to run either a 13t, or even better, 14t on the rear.
So something like a 29:13 or 30:14 would be good.

I understand that everyone loves to cream their pants about microdrive, but when durability and strength is at stake you're best to compromise clearance a little bit to run a 13t or 14t sprocket.

[bradh]

yeah, yeah... we all know you're antimicrodriveist...

;)

[rozza]

hrmm so I was right in the first place wow how about that so if I use 25,12 and the gearing distance is 54inches would that be about the same as riding a bmx bike with a 25,9 setup as that gear ratio has a 55inch gearing distance aswell?

[bradh]

hrmm so I was right in the first place wow how about that so if I use 25,12 and the gearing distance is 54inches would that be about the same as riding a bmx bike with a 25,9 setup as that gear ratio has a 55inch gearing distance aswell?
If we disregard tyre size, 25:9 on a bmx comes to 55.6 gear inches, whilst 25:12 on a (26"-wheeled) mtb gives 54.08 gear inches, so the latter would be slightly easier.

However, I tend to agree with rik, and, personally, I don't reckon I'd run anything smaller than a 13t in the back. But, you know... whatever.

[naz]

microdrive isnt worth the effort, put your money into a good mtb specific SS hub.
hadley SS (135mmX10mm bolts) 108 engagement point, absolute breeze to rebuild, strong as fuck freewheel system, bearings are as smooth as a babys bum.
Profile SS mtb hub (135mm X 10mm bolt up or QR(confirmed today))profile what more can you say. sexy smooth and profile add a Ti axle for wank.

ratios. stick with 2:1 then play around with variations.

chain: KMC coolchains are cheap and chunky am currently runnin one, but it keeps stretchin doing sprocket stalls
wipperman BMX stainless, 1.5tonne breakin load. hah.and you can get htem in funky colours.

sprocket: profile strong stays straighr grinding.

as much as id love to run a profile BMX SS (6 sealed bearing OHH) 110 to 135 runnin spacers is going to be dodgy, wheels wont be as strong coz the flange is going to be a touch closer and is more suited for a smaller 20" wheel. but i dont really know how much difference its going to make, im pretty sure it would still run symetrical flanges (no wheel dish), and runnin spacers is just dodgy, do it by all means but id really not advise it

[xero]

(Just re-read stuff...)



ah, no.


Sorry, but, ahhhh, no they won't. Particularly if we're talking about 26" wheels.


ahhh yes it will work..... its been done and runs fine(tried it just for the sake of it)
having said that, i am back to geared anyway
just do the math, but it comes down to rider preference anyway.........

[RCOH]

I used to run 22:13 on my rhythm & it was OK, but you a) spun out easily & b) the front chainring was too small to grind (chainstay yoke/tire) would hit ledge instead.

I have since upped to a 30:16 set up & it is possible to grind but i just don't have the talent.

Running less than 13tooth sprocket on the back does not allow enough chainlins to grip so the chain falls off under power. I found this out the hard way.

microdrive does look good though.

[bradh]

just do the math, but it comes down to rider preference anyway.........
I did do the math. 28:11 and 33:13 both come out at around 66 gear inches, as would 23:9, and whilst that's a little harder than average, I understand that some people would prefer it. 25:9, however, which is a fairly standard bmx ratio, gives a result in the 70s — 72.28, to be more exact — when used with 26" wheels. That's really quite hard, and it isn't a ratio I'd be recommending to someone who's looking to get into single-speeding.

[xero]

I did do the math. 28:11 and 33:13 both come out at around 66 gear inches, as would 23:9, and whilst that's a little harder than average, I understand that some people would prefer it. 25:9, however, which is a fairly standard bmx ratio, gives a result in the 70s — 72.28, to be more exact — when used with 26" wheels. That's really quite hard, and it isn't a ratio I'd be recommending to someone who's looking to get into single-speeding.

agreed but in the original question it was asked for the smallest gearing that could be had.......... thus my answer
a nice ss gearing is somewhere around 39/18 imo(wheelset dependant) but that wasn't the question.

lets leave it at that.

[bradh]

agreed but in the original question it was asked for the smallest gearing that could be had.......... thus my answer
a nice ss gearing is somewhere around 39/18 imo(wheelset dependant) but that wasn't the question.

lets leave it at that.
Cool. I meant no offence. I was merely concerned that if rozza was to go out and spend lots of money on a 25:9 setup, he'd end up with a ratio that in all likelihood wouldn't suit him.

[rozza]

hrmm yeah I came to the agreement with myself to go 28:13 gives me 56 gear inches so should be slightly harder to pedal then a bmx but should be about perfect for what I want, Thanks for the help guys and girls