Stability problem

Yardstick

Over the last few weeks I have noticed an alarming front wheel wobble if I ride no-hands at about 20 mph on my winter trainer. Up until recently the bike has always been very stable with my hands off the bars. However, now the front wheel, for want of a better description, casters with increasing resonance, such that if I were not to hold onto the bars the bike would crash.

I've checked the headset (it seems fine) and the skewer is tight. The front wheel bearings however have a little play. Could this be the cause of the problem?

JWSurrey

If you have adjustable hubs, then tighten up your cones - You'll need a thin spanner or a cone spanner - better still, two cone spanners - One to release the lock nut, the other to hold the cone!
The trick is to remove all play without over-tightening them.
If you're feeling daring, strip them down, clean up and re-grease with a Halfrauds pot of vehicle Lithium grease (more waterproof than LM grease and some others).

Park Tool has a good website with "destructions" for this type of thing.

Yardstick

Thanks for the reply. Not knowing how to tighten hub bearings is not the problem - and in all honestly I don't think it is the bearings play casusing the wobble. At the moment I have a odd wheels on this particular bike as I don't want the winter weather to trash the rims and freehub on the newer set I used during the summer (I've gone through 2 freehubs in a single winter before). The front wheel is an old 32 spoke CXP22 rim with a Miche hub (cup and cone bearings). There is about 5 mm of play- not a lot and frankly I can't be bothered to tighten it unless it might be the cause of the no-hands wobble.

The castering of the front wheel is odd. I can pedal along sans hands no problem, but if I sit up and coast at speed (particularly down hill) the front end starts this increasingly alarming resonant wobble. At first I though the front skewer had sheared it was that bad.

I just wondered if anyone else had encountered something similar and might be able to help with a diagnosis.

C1234

I get the same, though haven't done anything to diagnose it yet. I'd assumed it was the headset (even though it doesn't feel loose).

I've put a pair of tri-bars on too which might not be helping?

John.T

It could be slight pitting in the headset bearings with the balls just moving in and out of the pits. It does not need much to cause this and you can get a wobble if the bike is at all suseptable to it. Try slackening the headset off a little, just enough to give a little play. If this helps then that is the problem. You will need new bearing races. Don't forget to re-adjust after testing.

DavidBelcher

Interesting too see that a thread re. stability problems has appeared - had some problems of my own whilst out and about on Saturday afternoon. Whilst on the long descent of the A65 from Chelker reservoir to the Addingham by-pass, there was a definite "speed wobble", seemingly from the rear end of the bike. Can't quite fathom it out, as not much has changed on the bike (Look KG241 with Time Sprint fork, Vuelta Zerolite wheels & Mirage bits) since it was built up in July/August of 2007. Lovely weather, so no cross-wind to blame, plus I've ridden this road before with no bother. I had the steering column of the fork reduced in height a little bit last Autumn, but the front-end handling's till fine, so it can't be that. The bike, seeing as one has to be careful with carbon fibre, hasn't suffered any knocks or mishaps since I built it, either. Therefore, I've reached 2 conclusions;

(a) The tyres used to be Conti GP3000 back & front; swapped these for GP4000-S ones in October/November.
(b) It's me that has the stability problem! I'm just about recovered from a recent ear infection.

Would appreciate thoughts on the above, all feedback gratefully received.

Many thanks,
David