Crashes I nearly bought the farm due to the dreaded high speed wobblies.

[motorbikemike45]

I was in an unfamiliar to me area when I started down a very steep and long hill on my e-bike. The speed was exhilarating as the speedo went past 45mph. Then the front wheel/fork/handlebar began to oscillate out of control. I had had this happen before when I hit some uneven pavement at 70+ on my old and somewhat worn out Harley years ago. A friend I was riding with talked me into taking my hands off the bar and riding it out, slowing with the rear brake. It worked!

I had "the death-grip of fear" on the hand grips and my arms were absolutely rigid. It took a real mental effort to relax my hands and arms somewhat, but doing that and slowing the bike using both front and rear brakes cured the wobble and I survived.

It is sort of a difficult thing to do, but learning to ride without a death-grip on the grips and your arms relaxed will give you much greater control of your bike. Once the osillation begins, you have only a second or two before you are on your way to the pavement. Part of the cause of the wobblies is overcontrol by the rider, relax and enjoy the ride.

 

[Happy Valley]

Part of the cause of the wobblies is overcontrol by the rider, relax and enjoy the ride.

That and hitting 45mph heh, glad no mishaps ensued, you did well to keep it together at that speed, be careful out there.

 

[motorbikemike45]

I have tightened the steering tube bearings, which had worn in and gotten loose on this new(ish) bike. I'm a bit ashamed it had skipped my notice as I usually check things over more carefully. A bad lesson relearned, over and over.

 

[MikeJ]

Hi MotorbikeMike45 -

I know this is an old thread, but pertinent to me. I had the same description of front wheel wobble happen to me at about 27 mph on a smooth street. I slowed down as did you, and the wobbles stopped.

My front fork is a RockShox Dart 2, with 100 mm of travel. I invite other readers who experienced this wobble to reply with comments to prevent future front wheel wobble. I'm thinking that if the wobbles should happen again, that fork is being replaced with a fixed, heavy duty fork. My Haro fixed fork never wobbled even as I passed through 42 mph on it going downhill.

Thanks,
MikeJ

 

[Richard H.]

My front fork is a RockShox Dart 2, with 100 mm of travel. I invite other readers who experienced this wobble to reply with comments to prevent future front wheel wobble. I'm thinking that if the wobbles should happen again, that fork is being replaced with a fixed, heavy duty fork. My Haro fixed fork never wobbled even as I passed through 42 mph on it going downhill.

Yes and good general advice to bring it up. Suspension forks made for what is ostensibly called "mountain bikes" were never specced for high speed travel over a smooth surface, especially low/medium duty forks or any quality fork for that matter that has wear. I've over-hauled many bike suspension forks and the slider bushings become worn and develop play which produces the slight oscillations or wobble that extrapolates at the wheel axis during high speed. Cheapy bicycle suspension forks were never made to close tolerances to begin with. Riding in dirt, one can get away with a certain amount of play because the tire, usually a knobby, tends to purchase better on any ridge or rut in the trail and the rider is attuned to making constant small corrections. Not so at speed on pavement. These are NOT motorcycle forks that were specced accordingly. Just another chapter in the book of why a bicycle is just a bicycle. (often during these discussions someone will mention the Tour de France and how riders hit 60mph on the road course there conveniently overlooking that paid professional riders on a $8000 hand made bike with a chase van full of identical replacement is following, and serious crashes sometimes involving death is not uncommon)

 

[Cavi Mike]

Interesting concept of letting the bars go and slowing down. My old Ducati Monster used to tank-slap over 90 but you had to pull the handlebars as hard as you could to keep it under control. The lighter you held them, the worse it got. Then again, that was a sport-bike, not a cruiser.

 

[The_Aleman]

I also have RockShox Dart 2 100MM on my bike, but I have never once encountered speed wobble. I have nearly 5000 miles on the bike and have gone up to 40MPH.

I'm also relatively tall and lean over the bars slightly, too. My bearing preload is also slightly excessive, because I like a bit of drag.

 

[MikeJ]

I will try again. Maybe I had a not-tight-enough axle or maybe the headset was loose. They will be more closely examined and triple checked. I don't recall other riders having wobble problems, so I have to assume my setup had a hidden flaw in it. Testing will be in a few days. I will post the results after that time.

MikeJ

 

[Richard H.]

Something I always keep in mind with forums and online venues is that is that much of what gets passed on is anecdotal. One person uses a component and reports having satisfactory results with it but that does not necessarily make it universally applicable. There are too many variables and conditions that remain unremarked. Keeping your own counsel is a good idea and apply commonsense when considering what a manufacturer's design parameters were when building something meant to be pedaled by an average rider at 12 to 15 mph max and never specced to have an engine attached.

 

[The_Aleman]

I totally agree with you, Richard, but speed wobble is something that can be dialed out, for the most part. It can occur at any speed, not just speeds exceeding what's typically attained on a bicycle. As a longtime pedalhead, I've seen speed wobble in many forms and at many different speeds. Once you understand it, you can avoid it.

There are several factors involved in speed wobble on bicycles. Assuming the tire is mounted and aired up correctly, wheel is true, the forks are straight, much of what's left is weight transfer. If you have most of your weight over the rear axle of the bicycle, speed wobble is more likely to happen. Of course, some bicycles just have a bad headtube angle - something that's much more likely on poorly-designed frames - and combined with sitting too far back, can make speed wobble much more likely too.

The RockShox Dart 2, like most suspension forks, are definitely more loose than rigid forks. If you are getting speed wobble, they could make things worse. Increasing your bearing preload will help, but doublecheck all your components. Maybe even rethink your riding posture. Wikipedia has a lil article on speed wobble, too: http://en.wikipedia.org/wiki/Speed_wobble