I am gathering info wherever I can find it. Looking for a solution to bicycle high speed wobble. This as occurred with me whenever I hit 44 - 45 mph.
This last time was a run down. Mt. Washington on Vancouver Island. I tried moving my weight back this time to no avail. I got it calmed down but there
was more downhill so I tried putting my hands on the break hoods instead of the drops and about 40mph it went into a severe wobble, not just a shake.
Damm scary.
So, any bike riders out there? Anyone have experience with correcting? Other then slowing down, that one was already given to me by my smarter half.
I've goggled it, and there are lots of ideas. I need something that someone has tried and it works. I'm not a cat with nine lives.
Thanksbigkid - 21-9-2014 at 12:20 AM
Back in the days of 35 cent gas and a 63 corvette roadster, I retired my 10 speed super sport. One of the things that was a bit hard to deal with was
that my previous 10 speed was of lesser quality than the super sport. 8th Ave hill in south Seattle was one of my "lets try to get some air" weekly
rides. With most of your center of gravity over the front axle the high speed wobble was one of the reasons the pucker factor was part of the fun.
Back then it was a problem of loose bearings in the goose neck. After a stupit "hey watch this", I bent the front fork which pushed the front tire out
and inadvertently removed the pucker factor of 8th Ave hill. I retired the bike and up graded to the Schwinn Super Sport, no more wobble on the run
down 8th Ave.
By the way, whats an old man doing going that fast on a bike? Carol wasnt chasing you with the car was she?cheezycheese - 21-9-2014 at 04:50 AM
Maybe a steering damper, like the ones used on motorcycles will help.Aaeolien - 21-9-2014 at 06:51 AM
I would check to make sure stuff is adjusted properly. Headset, Wheel truing. I would be leaning towards something being not quite right with the
bike that only becomes noticeable at higher speeds. I have bombed down a few hills at 40+ with no wobbling like you are talking about.
Wobble?
skimtwashington - 21-9-2014 at 07:36 AM
Typically when someone say 'wobble' they are referring to side to side movement... as opposed to up and down....Is that it?
Most likely..in order of likeliness:
Loose headset( downtube of fork): check by fully applying front brake and push bike forward and back while straddling it. Should be
no movement(and possible 'clicking' sound from unwanted movement)
loose CONE(hub of wheel)-check by holding fork and trying to pull/push wheel sideways to left and right. Should be zero movement.
untrue wheel(rim)-needs to spin with no side movement. Also..If it moves up and down you have a flat spot(from pothole or..) and
damaged rim that can't be fixed.
Increased or high speed will make you more aware of even minor looseness or defect, not noticeable at slow speeds.fletcht - 21-9-2014 at 08:50 AM
Jeff, the bike is a Bianchi Veloce, not high end but not cheap either. No Carol wasn't chasing me, she wouldn't drive down the hill that fast.
I've checked for lose ness in the headset, it seems to be tight. Wheel looks to be true. But I haven' t had the spokes checked yet for matched
tightness. With motorcycles I have heard that if you encounter a high speed wobble (side to side) you can power through it. Hard to do on a 23mm wheel
at 44mph.
I we'll be re packing /replacing headset and wheel bearings. These opportunities for prolonged speed don't come that often but I would like to not
have to worry each time.
A couple of sites when googled insist that it is not a bearing problem. Removing weight from seat, and grasping top tube with knees can help solve
issue.
Thanks for the replies.
skimtwashington - 21-9-2014 at 09:24 AM
You didn't say if you checked the cone in your hub for looseness..(if you understood how I suggested to test it).
Don't overlook this.
You don't necessarily have to repack the wheel's cone bearings- unless many miles were put on......or...... if the cone was improperly adjusted to
begin with and you put lots of miles riding with this impropriety. This WILL wear bearings many times faster.
The bearings effect ease of spin- not wobble. Worn bearings don't spin as freely.
How you TIGHTEN the hub WILL effect any 'play' side to side(wobble).. So it may be just a simple tightening. (*see video)
When repacking bearings in cone wheel, it must be tightened just right.... just loose enough to spin freely, but not enough that you can wobble it by
pushing the top of wheel to either side.
The bike should not have any wobble at high speeds if all is right...as Aaeolien has pointed out.
"Removing weight from seat, and grasping top tube with knees can help solve issue.." doesn't sound like a good solution. It's a mere compensation.
* Here's a tutorial(special notice at 2:19 of video) :
Not that this is answer to your problem...but since you say headset is tight(using proper check).... it is most probably either wheel hub or untrue
wheel.
Good luck.snowspider - 22-9-2014 at 12:13 PM
Go on a bike forum that discusses road bikes and post your question. Much depends on the flexability of the frame and the geometry of the front fork
assembly. Wires ,brakes ,mirrors etc. hanging out in the wind can all induce a wobble. Powering thru a wobble can work in some cases in others it
ends catastrophically ,(do a youtube "speed wobble" search).rocfighter - 22-9-2014 at 12:29 PM
I got up to 22 on my bike last year and that was quite fast enough. I have not gone fast enough to get a wobble.
But I remember from my motor cycle days this could even happen if the tire pressure was not correct. Also I think I have seen in a publication that
some road racers have there tires balanced. So many factors to look at. sand flea - 22-9-2014 at 04:40 PM
I believe your speed wobble is in the wheels or tires.
If possible, try another set of wheels would be my best thought.
Are the tubes new or they have been patched?
Good luck and be safe
fletcht - 22-9-2014 at 05:14 PM
Thanks all for the suggestions. I have a few other mechanical things to look at. And some physical. The downside is, the opportunity is few and far
between. It seems I need to be at that speed for a short bit of time before it wobbles. I can go faster on a short hill near home but it is short
lived. Also I think rode surface might have a bit of influence. It is one of those things I hate to keep practicing to see if something works. Sooner
or later I won't make it through the wobble.
Kind of like cliff jumping. It is something you really can't practice for, they don't have training hills.
Feyd - 23-9-2014 at 07:22 AM
Many of the things skimtwashington listed COULD be the issue. AT they very least they can contribute to it. In addition a headset that is too tight
or a fork that is bent.
In general the wobble is more likely attributed to flex in the frame and fork. Wobble is simply an oscillation and the harmonics that come into play
need to be managed. Factors such as frame materials, the way the materials are used, the size of the frame, the rake and trail of the fork, the
weight of the rider and the bias of that weight, the length of the stem, drop of the bars are just a few of the factors. And if things aren't set up
properly for speed, a simple thing like a computer magnet set too closer to a valve stem and throwing the wheel out of balance can set the whole thing
into motion.
Even most mid-performance level bikes by and large are set up well enough out of the box to handle speeds within the 60mph range without issue. Of
course like anything speed related a lot of the safety factor and performance come from the skill level of the driver.
The simplest solution and usually the most useful for dampening road bike death wobble is to brace at least one knee firmly against the top tube.
Especially for heavier riders or riders on larger frames or frames that have a lot of flex. Most of the folks I know who have to deal with death
wobble on road bikes are running Ti frames. One guy I know was on a steel Guerciotti that was just whippy as hell.
If you set those knees before you accelerate you should disarm the situation by stiffening the frame/fork. You may have to shift your weight forward
or aft a bit to dampen things further. If you are fully weighted on the saddle that can be a big part of the problem. Bikes need to float under you,
road and mountain. bigkid - 23-9-2014 at 08:03 AM
Sorry, I had a vision of Carol driving down the road towing Evans behind her while he is riding his bicycle and he is yelling "44, not 40 more".
