Front wheel wobble

[Kingwill]

Hi

Still relatively new to road bikes and everything has been fine until recently.

I've suddenly noticed that on decending (I'm in Norfolk so that's not much of a decent!) at around 32MPH I get a lot of wobble at the front. It feels like my front wheel is out of true but I've checked and it seems true so I don't think it's that, any ideas?

 

[Dayvo]

Loose cone nuts, possibly!

http://www.sheldonbrown.com/cone-adjustment.html

 

[fossyant]

Speed wobble (does the front shimmy side to side). Try and relax a bit.

Motorbikers call it a tank slapper. TBH shouldn't be happening at 32mph.

Had it happen on an old road bike when mudguards were fitted, but this was at about 45-50 mph. Had it happen on another bike at 50 mph but in strong side winds.

Some bikes are more prone than others (geometry, wheels etc etc).

TBH, I've only had the two above situations in 25 years.

What bike is it ?

 

[Hip Priest]

I get that at when at high speed (high for me, anyway). I think it's just because I'm a nervous bike handler still. No doubt it'll come with experience.

 

[smokeysmoo]

I get that at when at high speed (high for me, anyway). I think it's just because I'm a nervous bike handler still. No doubt it'll come with experience.

Try clamping the top tube with your knees

 

[fossyant]

Try clamping the top tube with your knees

You only do that when you get speed wobble.

You need to relax. Death gripping a bike can cause it. You hold on, not hang on.

 

[smokeysmoo]

You only do that when you get speed wobble.

Yeah that's what I meant Fossy When it starts to wobble try clamping the top tube, don't try and clamp it when your peddling

 

[Norm]

Is it a high speed wobble (frequency of several times per second) or a low speed wobble (more like a weave)?

 

[gbb]

It happens occasionally to me on one particular hill at around 35mph.
Several things ive noticed / looked at. I'd descended it a few times on my Bianchi without problems.

First time it was on an old Raleigh with completely different geometry to my Bianchi. I put it down to that, but...

Second time i was on my Bianchi, so was i over cautious, over tense ?..perhaps.

I did realise i'd refitted my computer magnet near the innertube valve, as opposed to opposite it. Does that unbalance things...perhaps.

The road surface on that hill is horrendous, some of the top dressing is broken up so it's like riding over patchy stuck down gravel. Was my line taking me through even rougher broken up tarmac.

Headset if it's a little out of adjustment reputedly that can cause 'shimmy' at speed.

Having repositioned my wheel magnet, checked the headset (which was ok anyway), relaxed on that descent the next time i took it on the Bianchi...all was well. But then it could still be my line on a still rough surface.

 

[2Loose]

On the motorbike this can be made worse by tightening your grip on the bars - do you have white knuckles while descending? If so, relax...

 

[Bicycle]

I've had similar things on different slopes on the Malvern Hills.

(Also many years ago on motorcycles, but at different speeds).

1. Those who say loosen your grip are spot on. It feels wrong, but it keeps the thing stable.

2. Everything needs to be in the right place. Many times I've seen wheels on QRs that are clamped in place just a little out of alignment. It doesn't make itself known at lower speeds, but the whole plot can get wobbly when motoring.

3. Keep pedalling, even if not fast enough to propel the bicycle. It seems to help with holding the thing in a stable line.

 

[hotmetal]

I've had the same thing on my road bike (Giant TCR). It generally happens only if I'm in the drops, going fast and/or the surface is bad. I've come to the conclusion that it's a mixture of things:
1 - down in the drops I think I have too much weight on the bars, too far forward.
2 - the road surface triggers the shimmy, which makes me tense up and all I can do is try to slow down

It tends not to happen if I stay up on the hoods and get the weight back a little, and the pressure off the bars/my arms. The silly thing is, if I'm steaming down a hill, I like the drops for the fact that you can grab a handful of lever, as opposed to applying finger pressure from the hoods. (Very short hoods on mine: 2004 Campag Record, not long grips like Shimano). Yet getting in that position seems to cause more problems.

I agree with Bicycle on points 1 & 3 (can't comment on 2 though it sounds plausible). Pedalling does seem to stabilise things a bit, gyroscopic action I suppose. However IME trying to loosen your grip is easier said than done when you're also desperately trying to keep control of your "phoofie valve" at the same time though!

 

[SurlyNomad]

Ive had this before, never 5hit myself so much in my life! it was a hairy experience let me tell you. thought i was gonna die that day. Ever since ive worn a helmet. +1 on the advice given for gripping the top tube with your knees, seems to work for some reason.

 

[hotmetal]

Yes, someone should start selling activated-charcoal-filled waterproof cycling shorts! It is scary when it kicks in, mainly on account of the fact that you have to be doing 30+ before it starts.

Don't want to disillusion you though, but according to the 'experts' in the helmet threads (there be dragons!) a helmet will only protect you up to 12mph. I'd still rather have one than not, but don't count on it!

Is that for real, clamping the top tube with your knees? I think I'd prefer to keep the pedals turning, but maybe I'll try that next time instead (if rational thought can be brought to bear at the time!)

 

[dellzeqq]

it's called shimmy, and it used to happen more often, because steel bikes are more prone to it than aluminium or carbon. It can throw you off. I've known of one very experienced cyclists who never quite recovered his confidence or his health after a bad shimmy induced crash

people advocate all kinds of remedies including putting your upper thigh against the crossbar (difficult on a ladies bike......) but my chosen method was to haul on the rear brake and push my weight back, reasoning that if I did come to grief then it would be at a slower speed.