[Closed] Scary road moment....thoughts...

Speed wobble. Not sure what causes it but try shifting your weight on the bike. There are many theories but putting weight on the front helped me.

And you are correct it is a proper brown trouser moment whet it does happen.

I've experienced speed wobbles quite a lot, but the worst one was very much like you describe it. At the time I was convinced I had a puncture, and in my mind, it wasn't a case of if I was going down, but when! I was getting ready for it...

Thankfully there was absolutely no-one around me and it eased eventually, but was defo a brown trouser moment. In this instance triggered by a strong crosswind. But mostly I find they happen (usually much milder) when you're tense and hit the brakes.

Speed wobble. if you're sitting down when it happens stand up, if you're standing, sit down. You may also find that pedalling down hill also prevents it.

it's some kind of resonance isn't it? so you just need to change the resonant frequency of the bike. I seem to remember something simple as moving your knee so it touches the top tube can do it. standing/ sitting would probably work too but at speed it might not be that easy. I thought speed wobble happened at much higher speeds?

First time for me... no chance I could have stood up I would have gone down for sure. Pedaling may have helped but I was doing my best to lock my arms out to try a stop it vibrating and brake gently.

Maybe the wind from the car passing triggered it. I've had similar slight wobbles when lorries have gone past when riding solo at 25 odd mph, but that is normally a couple of wiggles, lock arms sorted.

This felt like for ever, front end was all over the place. Proper scary

locking arms is never a good idea.

hmmm, maybe my way of dealing with these isn't helping

This sounds a scary as hell, was it like this?

Another theory is if your in a tuck / speed position is to clamp the seat/frame with the inside of your legs. I tend to do that when going at speed.

Unless braking, I also generally have a light hold on the bars at high speed ( i.e. not white knuckle grip )

Yes it was like that! But felt like a hell of a lot longer, and I had a car on my right and a rider to my left who I knew I was close to. Thinking about it I was pedalling when it started as I was overtaking

I read about this so found a quiet road and induced a few minor wobbles. Found gripping the top tube with my knees stifled it immediately.

Check your headset's adjustment.

I've had this (as mentioned above) from strong cross winds whilst descending. Not pleasant! You should probably try to get into the habit of looking over your shoulder before moving out as well - you may have caused a brown trouser moment for the car driver also.

Is this like the equivalent of a tank slapper on a motorbike? I've never had this, but then I don't ride fast road bikes.

Were you gripping the bars really tightly? That'll do it.
Never had it on a road bike but on a motorbike when I got a tank slapper (try it happening at 120mph if you want some brown trousers), the best thing was to relax a little and let the bike smooth itself out.

Is this like the equivalent of a tank slapper on a motorbike?

Same thing happened to me on a Raleigh Chopper. That ended badly.

Never had it on a bicycle since. My KTM enduro bike would slap on rough flat out sections. Keeping it wound on and shifting weight right back sorted it out. Backing off once it started made it worse.

Check your headset's adjustment.

+1

I had this a few years back, going way too quickly on a rough descent. It was seriously scary with the bike bucking around and trying to throw me off. It took a long while to get my confidence back. Turned out to be a loose headset that was the culprit.

gofasterstripes - Member
Check your headset's adjustment.

I had similar the other day on a steep gravelly descent. There was a knocking noise from the front end too. Tightened headset and all's well with the world again.

I've had it happen on my road bike, best cure seems to be to put a bit more weight over the front wheel and no death-grip.

must tighten my headset this eve, it was loose on Sat.

You want a very light touch on the bars when descending at speed. Could it just be the 4x4 spooked you making you tense up mid-manoeuvre, which at 40mph is going to cause all sorts of trouble?

Happened to me twice, on exactly the same stretch of road. it's really knocked my confidence going downhill. Both times I was in the high 40's, possibly 50 mph. It is petrifying, the thought of going over the bars at that speed is not worth thinking about.

I've done a bit of research, and now i pedal downhill, even if I'm just slowly turning the cranks, without actually putting any power down. also a 'pro' tip is to lightly grip the top tube with your legs / knees, this does seem to give a more solid feel to the bike...

Thanks for the advice - I'll check the headset tonight - its not been touched since the bike was new 12 months ago so could be possible

Staying loose on a bike is hard when its wobbling all over the place and you think you are about to loose your teeth!

Happened again this morning when I got over 40mph... no where near as scary this time and easy corrected. Despite checking the headset the other day, I thought I would retighten it....half a turn tighter seems to have sorted it. Thanks for the help

On motorbikes it's due to steep steering angles. Is this a new phenomenon affecting modern bikes, maybe due to super stiff carbon frames not damping out any steering oscillations? I never remember it being a problem when I was a roadie in the 90's. we used to fly down some of the big hills in the peaks a really high speed on our 501/531/653 era bikes, easily 40 to 50 mph with no tank slappers.

I had this after changing to light weight wheels which where 800 g less than the stock Defy wheels and in the end I would hardly go down any hills and would not ride in the group the shop gave me my money back in the end as they did not want them fitted to any other bike incase there was a problem with them I have never had a problem again having refitted the stock wheels. I have been also no been told to have my knees clamping the top tube at speed.

If you think you had a brown trouser moment feel for this guy:

[img] [/img]

[Mick Dundee]Thats not a tank slapper...[/Mick Dundee]

**Dont mean to trivialise your incident OP, & glad your ok chap.
Its one of the things that used to put the fear of god into me when I had a road bike, & truth betold, probably one of the reasons I dont have one these days. Quite how those chaps on the Tour can do 50-60mph, in the rain etc, is simply terrifying.

both of those youtube clips look very similar. But, I wasnt dressed like a storm trooper I was wearing nothing more than lycra, plus I was in a group trying not to take mates out and also not end up under a 4x4. Mine was most definitely 100% more hardcore scary.