Speed Wobble!

[Deleted member 1258]

I don't remember having one on a cycle but I do remember having one on a motorcycle, scary.

 

[Racing roadkill]

I usually get a speed wobble if my wheels are misaligned. It's a very common occurrence if I've had to take a wheel out following a puncture, whilst on the road. I take care to make sure I realign after any long ride.

 

[TheJDog]

When my downtube broke (almost completely, also _all_ the welds around the BB were cracked) I got a horrendous speed wobble no-hands at anything over 5mph. Took me two days to work out what was wrong.

 

[e-rider]

Probably caused by a headset not being properly adjusted, or a wheel alignment (frame?) problem. In any case the way to stop a wobble is simply to clamp the top tube with your knees and put a bit more weight on the bars. Fixed. Slowing down means you go through all the problems at a slower speed.
Never heard of a problem with aluminium frames as described, if there was one the makers would soon find out (from users) and would have to sort it.
Was your mate using tri-bars? This is not a good control position at high speed (80km/hr plus), being a bit stretched can have some odd effects.

"....and put a bit more weight on the bars" I would think that would make it worse, not better, as a contributory factor to most speed wobbles is too much weight on the front wheel

 

[nickyboy]

I think it's very little to do with frame types, headsets, wheels and an awful.lot to do with riding style.

I've descended the Snake Pass to Glossop something like a hundred times. It's fast and long and a nice safe descent. Except one time.

I was cutting the apex on a bend and hadn't seen a car coming the other way. I tensed up and steered away although still at speed. Massive speed wobble ensued. All I could do was go in a straight line and do my best to stop. Set off descending again and I was pretty tense. And it happened again.

Now in the hundreds of descents I've done those are the only speed wobbles. I normally descend just very gently holding the bars and weight out of.the saddle. So I reckon it was tensing up the first time and then.being unable to relax again for the second.

 

[screenman]

One of my bikes would start to wobble at 46mph, it was not a rider fault as far as I know.

Think of the rotating force of a wheel at speed, out of balance and it will want to vibrate.

 

[Fab Foodie]

"....and put a bit more weight on the bars" I would think that would make it worse, not better, as a contributory factor to most speed wobbles is too much weight on the front wheel

I disagree. But it's hard to explain ....
You have 3 contact points with the bike, as long as one of them is loose there should be no problem. When someone has the bars in a death grip, their buttocks clenching the saddle and toes curling around the pedals, there is more chance of the bike ahaking. Relaxing one of those points then the bike can wriggle around without you fighting against it. Find your fave hill and try it!

 

[ColinJ]

I think it's very little to do with frame types, headsets, wheels and an awful.lot to do with riding style.

I've descended the Snake Pass to Glossop something like a hundred times. It's fast and long and a nice safe descent. Except one time.

I was cutting the apex on a bend and hadn't seen a car coming the other way. I tensed up and steered away although still at speed. Massive speed wobble ensued. All I could do was go in a straight line and do my best to stop. Set off descending again and I was pretty tense. And it happened again.

Now in the hundreds of descents I've done those are the only speed wobbles. I normally descend just very gently holding the bars and weight out of.the saddle. So I reckon it was tensing up the first time and then.being unable to relax again for the second.

I agree. I think the first time that my riding partner had a problem off Holme Moss it was because he had frightened himself going into a tight RH bend too fast and was desperately trying to scrub off speed. A year later, he had switched from a steel touring bike weighing over 30 pounds to a carbon fibre racing bike weighing about 17 pounds but the shimmy happened again at the same spot. I reckon he remembered the fear when nearly crashing the year before, tensed up, and caused it again.

I felt relaxed, had a loosish grip on the bars, my arms bent, one knee against the top tube, and had eased my weight slightly off the saddle.

Of course I will now experience a bad shimmy on the 50 mph descent off the Trough of Bowland summit on my forum ride on Sunday!

 

[e-rider]

I disagree. But it's hard to explain ....
You have 3 contact points with the bike, as long as one of them is loose there should be no problem. When someone has the bars in a death grip, their buttocks clenching the saddle and toes curling around the pedals, there is more chance of the bike ahaking. Relaxing one of those points then the bike can wriggle around without you fighting against it. Find your fave hill and try it!

I personally have never experienced any kind of speed wobble, in many years of cycling and getting up to 50 mph
However, I've had the 'tank slapper' on a motorbike several times!

 

[dr snuggles]

I've had it on carbon in Majorca a couple of years ago.
My opinion is definitely riding style. I've got a tendancy to tense up while descending and when I'm tired I reckon that's a recipe for disaster.
Very scary experience I certainly never want to repeat. Gripping the top tube definitely helps.

 

[robjh]

I've had it three times. Twice were on heavily-laden steel tourers with heavy but no doubt slightly unbalanced front panniers, and I came off the bike. Those seemed explicable, the speed wasn't too great and they didn't scare me. Once however was on a light aluminium bike, on a main road at about 40mph and scared the shoot out of me. It's impossible to know exactly what the cause was but it has made me more cautious ever since. I now practise the 'clamp your leg against the top tube' precautionary method but still don't trust myself on fast descents as I did before.

 

[Dirk]

Speed wobbles are caused by numerous different factors.
My motorcycle club was involved in a film in the late '70s about this subject - I had a fleeting moment of cinematic fame. LOL.
I don't know if the film is still available, but it's worth a watch.
It was made by Dunlop and it's called ' Wobble and Weave'.

Edit - found it on You Tube

View: http://youtu.be/z3OQTU-kE2s

 

[Deleted member 1258]

Speed wobbles are caused by numerous different factors.
My motorcycle club was involved in a film in the late '70s about this subject - I had a fleeting moment of cinematic fame. LOL.
I don't know if the film is still available, but it's worth a watch.
It was made by Dunlop and it's called ' Wobble and Weave'.

Edit - found it on You Tube

View: http://youtu.be/z3OQTU-kE2s

 

[Sara_H]

I once had a speed wobble on hired bike when I was doing the Vienna to Budapest tour. Long, steep downhill. Scared me to death. Never gone so fast since, hence no more speed wobbles!

 

[Venod]

Edit - found it on You Tube

Thats it then put on some weight and give someone a backy going downt Moss.