A bike that does not shimmy / speed wobble

[gbb]

Narrowing down a shimmy is very hard.
My first was on a 531 framed Raleigh on a quite steep descent. I'd never had it happen before but the road surface was quite rough.
Mechanically the bike was quite sound, no known problems, wheels were R500s which do flex a bit...i did wonder at the time was that the cause.

FFWD a few years, A Bianchi Via Nirone didn't have any shimmy, then a Ribble carbon which didnt...until after I had a couple years out through illness, then I've suffered from shimmy frequently and on one occasion it happened at relatively low speed as I started a descent.
I have to feather the brakes now if my speed gathers above or around 25 mph, I've lost confidence a bit. I still try to push and let the bike go but rough road surface seems to trigger it, that much I have realised. Headset poorly adjusted can be a reason but I'm not convinced mine's out.

I sympathise, it's horrible. Kinda glad I don't live in hilly terrain.

 

[User65906]

Narrowing down a shimmy is very hard.
My first was on a 531 framed Raleigh on a quite steep descent. I'd never had it happen before but the road surface was quite rough.
Mechanically the bike was quite sound, no known problems, wheels were R500s which do flex a bit...i did wonder at the time was that the cause.

FFWD a few years, A Bianchi Via Nirone didn't have any shimmy, then a Ribble carbon which didnt...until after I had a couple years out through illness, then I've suffered from shimmy frequently and on one occasion it happened at relatively low speed as I started a descent.
I have to feather the brakes now if my speed gathers above or around 25 mph, I've lost confidence a bit. I still try to push and let the bike go but rough road surface seems to trigger it, that much I have realized. Headset poorly adjusted can be a reason but I'm not convinced mine's out.

I sympathise, it's horrible. Kinda glad I don't live in hilly terrain.

Hi gbb, is that Alex R500 wheels, for this is what is on the bike I have, though I
have not actually read or heard of anyone linking these wheels to speed wobbles.
I don't quite know how fitness / illness or lack of would cause a bike to wobble, unless balance
was the issue, but I was on a straight stretch, not the roughest part of the road either, I tried to
up the speed again after to see what would happen, expecting it to happen again as the road
was now rougher and wavey but to no avail, I swung about a lot, swerving standing up moving
weight around and nothing that one would not expect occurred, am really hoping it was tire
pressure, am 12 stone 10 lbs, and the pressure the day after the ride was 96 lb in the back, and front,
which was a little lower than where I set it at 100 lb in the back, I have gone lots lower on other bikes
and they just kept on tracking through whatever, no wobbling, the tires are 25mm

 

[Fab Foodie]

Chapter and verse on the subject....

https://www.sheldonbrown.com/brandt/shimmy.html

 

[Drago]

Speed wobble? You lightweights. I'm the one that took a Raleigh Chopper to transonic speeds and lived - Just - to tell the tale.

 

[Goggs]

Speed wobble? You lightweights. I'm the one that took a Raleigh Chopper to transonic speeds and lived - Just - to tell the tale.

Me too. On a Tomahawk!

 

[Drago]

Chuck Yaeger was inspired by my antics and went on to fly the X1 through the sound barrier.

 

[gbb]

I'e read and read on the subject but it' never narrowed it down for me.
Shimano R500 wheels. I don' think they were the issue, just wondered at the time. I'm now on Racing 5s, same issue.
Illness linked...no of course but as a result of that illness I gained weight so my weight distribution is different now...but then I was light when it first happened. Now I'm heavier...it still happens although more frequently.
I even tried different tyres on the front, no change.
In the end I suspect a lot is confidence/ nervousness/ not being relaxed etc.
I did give my headset another looking at post my last ride...meh, maybe there was a tiny bit of play...ive adjusted it again and will see.

 

[User65906]

Speed wobble? You lightweights. I'm the one that took a Raleigh Chopper to transonic speeds and lived - Just - to tell the tale.

 

[adamhearn]

It just happens to some configurations and those are dependent on rider, bike, speed, weather, road surface, etc. I had it once on one of my bikes and it was pretty scary but then I've done many miles and some much faster since and it hasn't recurred. Does it concern me? Nope but if it does you that much, ditch the bike and get another and hope you don't experience again...

https://www.sheldonbrown.com/brandt/shimmy.html

 

[Fab Foodie]

It just happens to some configurations and those are dependent on rider, bike, speed, weather, road surface, etc. I had it once on one of my bikes and it was pretty scary but then I've done many miles and some much faster since and it hasn't recurred. Does it concern me? Nope but if it does you that much, ditch the bike and get another and hope you don't experience again...

https://www.sheldonbrown.com/brandt/shimmy.html

TMN to me I think....

 

[User65906]

Am getting another bike, but i would still like to know how the wobble was instigated,
it never happened me before, so why now, I am worried about it, because if it was wet
I would have been off, worse still, if cars were coming I would be in under one of them,
being on a bike that wont steer gives seriously limited options.

 

[biggs682]

Am getting another bike, but i would still like to know how the wobble was instigated,
it never happened me before, so why now, I am worried about it, because if it was wet
I would have been off, worse still, if cars were coming I would be in under one of them,
being on a bike that wont steer gives seriously limited options.

Nothing worse than jumping on a bike and having an issue like the wobble described , and i am not surprised it has put you off riding it

As for a reason who knows could be a mixture of issues and reasons

 

[GuyBoden]

Check frame alignment, put a piece of string all around the frame, from the headtube to the rear dropouts and back to the headtube.
The seat tube should be central and the top tube should be central between the string.