Death Wobbles

[mtb1611]

Greetings all. As many of you know, a short wheelbase road bike and high speeds are not comfortable bedfellows. A mate of mine has over the last few weeks had the deat wobbles a couple of times when exceeding 65kph. He's had a the bike for a couple of years and has exceeded that speed many a time without the wobblies. He swears that all is well and good with his bike. Any suggestions?

[n plus one]

In motorbike world the tail wags the dog; most headshake issues originate in the rear suspension.

Headshakes on a pushie? I'd start with headset bearing adjusment and then work through to frame alignment.

Eliminate the easy things first - change out the tyres etc.

Does the bike shake its head with the hands off the bars? Ballsy thing to check but human input often compounds cyclical osilation - witness moto GP bikes that tankslap till their riders are thrown and then sit up and go dead straight into a the tyre wall.

Probably a little too invovled but there you go...

[mtb1611]

Tyres shouldn't cause death wobbles. As for everything else, he's pretty meticulous but as I haven't inspected the bike myself I can't be 100% sure. I'd recommended to him that he pretty much check every single item on the bike that can be loosened or tightened to ensure that nothing is loose. Will have to wait a and see. Cheers for the advice mate.:)

[slip]

Speaking from Moto experience (on road) - depending on the bike/speed/situation they can be settled by locking in with elbows and knees, and forcefully stabilising things. They get really bad when the wobble is allowed to increase or made to increase through overcorrection or too late corrections. A male should be able to lock a wobbling bike down.

[DarrenHunt]

There are many things that can give you the death wobbles on a pushie, excluding the bike setup, i've had them as low as 40km/h (mind you there was an 80km/h cross wind).

If you're putting too much weight over the front wheel your more likely to get the wobbles.
If you're holding the handle bars in the wrong manner (you want looser hands)

the actual position on your bike can also play a role.

65km/h death wobbles though... he is definately doing something a bit odd.

[No Skid Marks]

I don't want to know this shit. I'm trying to see how fast I can go on my new road bike. WTF do you do if you get wobbles? Ya'll just joking right?

[alexb618]

wind direction can cause this sort of stuff too

not just strong winds either...

[DarrenHunt]

I don't want to know this shit. I'm trying to see how fast I can go on my new road bike. WTF do you do if you get wobbles? Ya'll just joking right?

dont worry, if you do everything right you shouldn't get them unless its heaps windy. tripple figures and no wobbles.

if you get the wobbles dont touch the brakes... front especially
loosen the grip of your hands, so your still honding it but not gripping (to kinda let the front wheel find its own path)

[n plus one]

I don't want to know this shit. I'm trying to see how fast I can go on my new road bike. WTF do you do if you get wobbles? Ya'll just joking right?

Two options, power on or crash...

[n plus one]

Tyres shouldn't cause death wobbles.

True, but nor should any other part of the bike and tyres are shit easy to eliminate...

[tofer]

I would check the inside of the frame where the front fork sits in it. If it's a carbon bike it is especially hard to tell if there is even a hairline fracture, this could cause the wobbles and I would definately NOT ride it. also check the fork steerer. Again if it's carbon its hard to check properly, so personally (considering at 60km/h falling off can break a few bones) I would get it professionally checked.

[DarrenHunt]

I would check the inside of the frame where the front fork sits in it. If it's a carbon bike it is especially hard to tell if there is even a hairline fracture, this could cause the wobbles and I would definately NOT ride it. also check the fork steerer. Again if it's carbon its hard to check properly, so personally (considering at 60km/h falling off can break a few bones) I would get it professionally checked.

death wobbles more often than not has nothing to do with the bike, 60km/h isn't exactly fast either

[fkdbikes]

Whatever the cause DONT let your mate try letting go of the bars to test this! 65k's an hour is fast enough to seriously fuck him up!
Check the wheel bearings
Check the tyre
check the spokes
Check the headset
Check the frame and forks, see if you can get someone to use a guage to check alignment.
It's not normal and means there's something seriously wrong.

[ScottD]

how long is your stem?

[I-AM-TEH-FASTEST-11]

you SHOULDN'T get death wobbles, I've been well over the 80kph mark, even over 90 and never had them, even after hitting debris.
If it's a bike related you probably won't be able to tell with a simple check over. Even experience mechanic's can't tell from simply checking over a bike. It usually involves test riding, and then pulling apart the headset, front hub and checking over anything likely to have stress fractures through it. Seating of the tyre is possible, but unlikely as you wouldn't notice it, as you would tension of the spokes.
We then go to rear of the bike, check the rear hub, the BB (unlikey to cause wobbles) and the rear triangle. If you still find no issue after completly stripping, regreasing and rebuildign the bike, you have to look at rider error.

User error is very common in this sort of thing, even though riders claim to have ridden for years and know everything, they generally are completly useless on a bike and need to be slapped into place.

There is also a level of imagination that comes with peoples bikes i.e fear of high speeds and fear of being laughed at. Make sense? If he is scared of going fast, but doesn't want to be mocked, some imaginary bike problem could definately be the answer.

I have seen all of the above in any varity of forms, and the later 2 being the most common. Mind you this is from a mechanic, and ride leaders point of view, so it comes with the territory.

I hope I was of some help with my vauge ramblings.