First speed wobble crash
09-07-20, 11:23 AM
#51
Senior Member
Join Date: Nov 2015
Location: Austin & Telluride
Posts: 53
Bikes: Parlee Chebacco for now
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 15 Post(s)
Liked 0 Times
in
0 Posts
09-07-20, 12:01 PM
#52
Senior Member
Join Date: Jan 2005
Location: Mountains and Plains of Colorado
Posts: 241
Bikes: 2005 Seven Odonata (DuraAce /Reynolds),1983 Trek 950 (Mavic/Suntour/Regina), 1986 Stumpjumper Shimano/Suntour/Regina), 1986 MASI 3V, (Campy/Mavic/Regina) 1995 Schwinn LeTour (Suntour/Wienmann/Phil/Shimano/Regina): All Brooks Saddles
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 25 Post(s)
Likes: 0
Liked 2 Times
in
2 Posts
I've had that happen on three different bikes, one on which I attained 67 years ago mph going down a mountain pass. That one was a Trek 957. 20 years later, I experienced the wobble on the same bike while on an organized tour at about 40 mph. It was me, being older and getting a little more cautious. The other two times were on a brand new 7 and a Schwinn Letour. Same thing and each time it was a long straight. Have never experience it bombing down a canyon with lots of curves. I've since learned to relax and when I start getting a little tense about the speed, slow it down.
09-07-20, 12:13 PM
#53
Senior Member
Today I experienced a shimmy that I couldn't control. I went for a ride today and twenty minutes in I was descending a hill at 56 km and then in no time I am skidding along the pavement. The shimmy turned into a full out wobble that I just couldn't get under control.
Two weeks ago I experienced shimmy at 82 km an hour and I was able to slow the bike down and control it. I had a smaller one a few days ago at about 70 km/h. Today's was much slower but I had hit some rough pavement that may have contributed to the wobble.
Did I help contribute to this mishap, you bet I did. I didn't grab the top tube between my legs, I didn't raise my weight above the saddle or loosen my grip on the bars. These are all solutions but they are counter-intuitive when it is happening. I was hanging on for dear life, just trying to slow the bike down. I think I need to start training for this to make sure it doesn't happen again. I have done a lot of reading on speed wobble and one thing is clear, there is no definitive answer. Different solutions work for different people and the solutions are not universal. My biggest obstacle will be fear. The fear to go downhill fast again.
This is just a narrative of what happened. I was one of the unlucky ones that couldn't control today's shimmy.
The bike was the Trek Domane SL6 that is one year old exactly today.
Two weeks ago I experienced shimmy at 82 km an hour and I was able to slow the bike down and control it. I had a smaller one a few days ago at about 70 km/h. Today's was much slower but I had hit some rough pavement that may have contributed to the wobble.
Did I help contribute to this mishap, you bet I did. I didn't grab the top tube between my legs, I didn't raise my weight above the saddle or loosen my grip on the bars. These are all solutions but they are counter-intuitive when it is happening. I was hanging on for dear life, just trying to slow the bike down. I think I need to start training for this to make sure it doesn't happen again. I have done a lot of reading on speed wobble and one thing is clear, there is no definitive answer. Different solutions work for different people and the solutions are not universal. My biggest obstacle will be fear. The fear to go downhill fast again.
This is just a narrative of what happened. I was one of the unlucky ones that couldn't control today's shimmy.
The bike was the Trek Domane SL6 that is one year old exactly today.
09-07-20, 01:56 PM
#54
Newbie
Dunlop wobble & weave
I ride bikes and motorcycles. This video from Dunlop tires, in the 70s about how & why MCs wobble & weave, is quite interesting. Notably, they differentiate between wobble and weave. A big surprise was how both weight placement and size of rider makes such a difference. This could explain why some of you have recurring trouble and others do not. And why a head wind (changing weight balance) can make a difference. Since I am a new poster, this site won't let me post the site, but go to Youtube and then Dunlop Wobble & Weave.
09-07-20, 02:02 PM
#55
Newbie
Join Date: Jun 2020
Posts: 4
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I don't think I have seen spoke tension mentioned yet in this thread. I were having repeated wobble issues, I would want to be sure it wasn't starting with slightly loose spokes.
Prior to reading this tread, I wasn't aware that "speed wobble" was a thing. I think I experienced it a few times as a teenager and intuitively shifted my weight and clamped the top tube in the right way. I don't think anyone ever told me to do that, but still, when I make a fast descent, I often clamp the top tube with my knees (before any wobbling starts).
Prior to reading this tread, I wasn't aware that "speed wobble" was a thing. I think I experienced it a few times as a teenager and intuitively shifted my weight and clamped the top tube in the right way. I don't think anyone ever told me to do that, but still, when I make a fast descent, I often clamp the top tube with my knees (before any wobbling starts).
09-07-20, 05:23 PM
#56
steveraleigh
Join Date: Jul 2015
Location: Emerald, Victoria Australia
Posts: 2
Bikes: Colnago steel superissimo, Detto Pietro (Steel). Raleigh fixi, GT Cross, Alloy customised roadie.
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I had the same issue. I had a cheap generic threadless headset on a steel frame road bike that I checked after a speed wobble and there was slight movement in it.
I replaced it with a Cane Creek headset which is better constructed and fits together better.
09-07-20, 06:27 PM
#57
Senior Member
Here’s a long discussion by Lennard Zinn on bike geometry issues related to wobble and mechanical resonance.
https://www.velonews.com/gear/techni...speed-wobbles/
Worth noting here, per our previous discussion, that a number of his customers came to him with serious wobble and resonance issues on stock carbon frames. Point here is that it can happen to anyone given the right conditions in bike construction, geometry and adjustment when presented with that variance in order weight, body position, and riding conditions.
Mechanical resonance issues are tricky and very often counter intuitive to solve.
https://www.velonews.com/gear/techni...speed-wobbles/
Worth noting here, per our previous discussion, that a number of his customers came to him with serious wobble and resonance issues on stock carbon frames. Point here is that it can happen to anyone given the right conditions in bike construction, geometry and adjustment when presented with that variance in order weight, body position, and riding conditions.
Mechanical resonance issues are tricky and very often counter intuitive to solve.
09-08-20, 07:15 AM
#59
Senior Member
Join Date: Sep 2008
Posts: 781
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 479 Post(s)
Liked 277 Times
in
156 Posts
Loose headsets, wheels out of true, loose spokes, hubs, drops vs hoods, carbon resonance, tall riders, tall frames, bikes in the '80s... It seems every component is the culprit.
It's the rider. Seriously. The majority of cyclists will ride many bikes over many years and never experience this, while other riders will experience this on every bike they ride.
I've got to believe that points to either that rider's position or behavior or both.
- Position: how the bike is set up and how the rider is sitting on the bike at the time of the wobble, e.g. hoods, drops, forward, back, low, upright, etc.
- Behavior: how the rider acts and reacts to input and feedback, e.g. loose and absorb; stiff and amplify
It's the rider. Seriously. The majority of cyclists will ride many bikes over many years and never experience this, while other riders will experience this on every bike they ride.
I've got to believe that points to either that rider's position or behavior or both.
- Position: how the bike is set up and how the rider is sitting on the bike at the time of the wobble, e.g. hoods, drops, forward, back, low, upright, etc.
- Behavior: how the rider acts and reacts to input and feedback, e.g. loose and absorb; stiff and amplify
09-08-20, 10:54 AM
#60
Senior Member
Join Date: Apr 2011
Location: Alpharetta, GA
Posts: 15,280
Bikes: Nashbar Road
Mentioned: 71 Post(s)
Tagged: 0 Thread(s)
Quoted: 2934 Post(s)
Liked 341 Times
in
228 Posts
Regardless of the specific cause in the given incident we know that speed wobble is a resonance with some kind of positive feedback that builds the resonance. (it could also be a negative control input feedback that is time-delayed just the wrong amount).
With it happening that frequently, I'd be changing anything on the bike that could be contributing. Sometimes (usually?) a lot of otherwise unrelated factors have to be just right to make it happen. Starting with tires even because that's the cheapest and easiest, but it would be a good excuse to upgrade the wheels. Handlebar width. Lube the headset. Weight distribution on the bike, tweaking the rider position.
If it's the case that control input is contributing, the recommendation that I've seen and which has worked for me is "stop fighting it". Also relax in the arms and upper body, but it needs to be almost instant.
With it happening that frequently, I'd be changing anything on the bike that could be contributing. Sometimes (usually?) a lot of otherwise unrelated factors have to be just right to make it happen. Starting with tires even because that's the cheapest and easiest, but it would be a good excuse to upgrade the wheels. Handlebar width. Lube the headset. Weight distribution on the bike, tweaking the rider position.
If it's the case that control input is contributing, the recommendation that I've seen and which has worked for me is "stop fighting it". Also relax in the arms and upper body, but it needs to be almost instant.
09-08-20, 01:19 PM
#61
Pizzaiolo Americano
Loose headsets, wheels out of true, loose spokes, hubs, drops vs hoods, carbon resonance, tall riders, tall frames, bikes in the '80s... It seems every component is the culprit.
It's the rider. Seriously. The majority of cyclists will ride many bikes over many years and never experience this, while other riders will experience this on every bike they ride.
I've got to believe that points to either that rider's position or behavior or both.
- Position: how the bike is set up and how the rider is sitting on the bike at the time of the wobble, e.g. hoods, drops, forward, back, low, upright, etc.
- Behavior: how the rider acts and reacts to input and feedback, e.g. loose and absorb; stiff and amplify
It's the rider. Seriously. The majority of cyclists will ride many bikes over many years and never experience this, while other riders will experience this on every bike they ride.
I've got to believe that points to either that rider's position or behavior or both.
- Position: how the bike is set up and how the rider is sitting on the bike at the time of the wobble, e.g. hoods, drops, forward, back, low, upright, etc.
- Behavior: how the rider acts and reacts to input and feedback, e.g. loose and absorb; stiff and amplify
09-08-20, 01:56 PM
#62
Senior Member
Join Date: Sep 2008
Posts: 781
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 479 Post(s)
Liked 277 Times
in
156 Posts
Anyone who's ridden for only a couple years has ridden a bike with a loose spoke, loose headset, a wheel out of true, etc. A = B and B = C but A does not = C.
09-08-20, 03:21 PM
#63
Full Member
Join Date: May 2009
Location: WI
Posts: 262
Bikes: 2010 Bob Brown Cycles tandem, 2019 Co-Mo Carrera tandem, 1980 Richardson tandem, 2014 Cervelo R3, 2018 Specialized Roubaix, 1985 Bianchi Campione, 1983 Trek 720, 2020 Trek Fuel EX8, 2021 Salsa Mukluk
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 72 Post(s)
Liked 116 Times
in
70 Posts
Not in my case. As I posted earlier, I've only experienced this on one bike, and I've tried everything possible to remedy the situation with no success. I've owned dozens of other bikes over the years and have never had this problem with any of them.
09-08-20, 05:40 PM
#64
Pizzaiolo Americano
That's my point. As each rider with a wobble searches for the cause, they'll find a loose headset, loose spoke, hub issue, tall frame, carbon resonance issue...
Anyone who's ridden for only a couple years has ridden a bike with a loose spoke, loose headset, a wheel out of true, etc. A = B and B = C but A does not = C.
Anyone who's ridden for only a couple years has ridden a bike with a loose spoke, loose headset, a wheel out of true, etc. A = B and B = C but A does not = C.
09-08-20, 05:55 PM
#65
For The Fun of It
Join Date: May 2007
Location: Louisissippi Coast
Posts: 5,851
Bikes: Lynskey GR300, Lynskey Backroad, Litespeed T6, Lynskey MT29, Burley Duet
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 2134 Post(s)
Liked 1,644 Times
in
826 Posts
This is incredibly interesting to me. I knew motorcycles could get headshake in certain circumstances, but I had no idea bicycles could. With that said, I don't trust my Lynskey Backroad at more than about 37. It starts feeling, for lack of a better word, light in the the front end. Like if I pushed it, It would lose stability. I have run a lot of bikes over 40 and have bumped 50 once. I never felt anything other than perfectly planted. For those of you who have experienced it, did it feel glued to the road one second and the next it started the wobble, or did it telegraph that it was entering an unhappy zone.
09-08-20, 10:04 PM
#66
Senior Member
Regardless of the specific cause in the given incident we know that speed wobble is a resonance with some kind of positive feedback that builds the resonance. (it could also be a negative control input feedback that is time-delayed just the wrong amount).
With it happening that frequently, I'd be changing anything on the bike that could be contributing. Sometimes (usually?) a lot of otherwise unrelated factors have to be just right to make it happen. Starting with tires even because that's the cheapest and easiest, but it would be a good excuse to upgrade the wheels. Handlebar width. Lube the headset. Weight distribution on the bike, tweaking the rider position.
If it's the case that control input is contributing, the recommendation that I've seen and which has worked for me is "stop fighting it". Also relax in the arms and upper body, but it needs to be almost instant.
With it happening that frequently, I'd be changing anything on the bike that could be contributing. Sometimes (usually?) a lot of otherwise unrelated factors have to be just right to make it happen. Starting with tires even because that's the cheapest and easiest, but it would be a good excuse to upgrade the wheels. Handlebar width. Lube the headset. Weight distribution on the bike, tweaking the rider position.
If it's the case that control input is contributing, the recommendation that I've seen and which has worked for me is "stop fighting it". Also relax in the arms and upper body, but it needs to be almost instant.
Likes For Racing Dan:
Likes For Sorg67:
09-09-20, 01:50 PM
#69
Senior Member
Join Date: May 2018
Location: Fargo ND
Posts: 898
Bikes: Time Scylon, Lynskey R350, Ritchey Breakaway, Ritchey Double Switchback, Lynskey Ridgeline, ICAN Fatbike
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 463 Post(s)
Liked 546 Times
in
306 Posts
Ouch! Hope you heal up quickly.
That was the drill for those flexible flyers of the 1980's. John gave a very good explanation of the forces involved. Basically anything that can create a vibration can cause this, so most of the suggestions may help.
I have a Peugeot CFX-10 from the early 1980s with a 61 cm top tube. It seems to wobble if anything is wrong. One item which has changed the wobble point on that bike is tire balance. Patch a tube, by the side of the road, wobble at 30 MPH. Good wheel balance, wobble at 35, so I would add wheel balance to the list of wobble causes.
The classic advice given is to clamp the top tube between your knees. This works if it’s the top tube (less but still effective if down tube) that’s oscillating. What this does from a frequency perspective is make your top tube shorter so that you push the resonant frequency higher. Once it’s higher, then it will stop oscillating from the current input frequency because it’s no longer the resonant frequency. Of course, this is going to matter what the frequency is, where you clamp your knees on the tube etc.... So that’s why it doesn’t work *all* the time.
Scary problem. Been there.
J.
Scary problem. Been there.
J.
I have a Peugeot CFX-10 from the early 1980s with a 61 cm top tube. It seems to wobble if anything is wrong. One item which has changed the wobble point on that bike is tire balance. Patch a tube, by the side of the road, wobble at 30 MPH. Good wheel balance, wobble at 35, so I would add wheel balance to the list of wobble causes.
09-09-20, 04:09 PM
#70
Senior Member
Ouch! Hope you heal up quickly.
That was the drill for those flexible flyers of the 1980's. John gave a very good explanation of the forces involved. Basically anything that can create a vibration can cause this, so most of the suggestions may help.
I have a Peugeot CFX-10 from the early 1980s with a 61 cm top tube. It seems to wobble if anything is wrong. One item which has changed the wobble point on that bike is tire balance. Patch a tube, by the side of the road, wobble at 30 MPH. Good wheel balance, wobble at 35, so I would add wheel balance to the list of wobble causes.
That was the drill for those flexible flyers of the 1980's. John gave a very good explanation of the forces involved. Basically anything that can create a vibration can cause this, so most of the suggestions may help.
I have a Peugeot CFX-10 from the early 1980s with a 61 cm top tube. It seems to wobble if anything is wrong. One item which has changed the wobble point on that bike is tire balance. Patch a tube, by the side of the road, wobble at 30 MPH. Good wheel balance, wobble at 35, so I would add wheel balance to the list of wobble causes.
09-09-20, 09:18 PM
#71
Senior Member
Join Date: Jan 2006
Location: northern Indiana
Posts: 231
Bikes: Peugeots: 1980 pkn10, 1982 psv10; LeMond alp d'huez; Austro Daimler Vent Noir; Specialized Allez steel dbl
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 3 Times
in
1 Post
Could the reason for the high speed instability is that the bike in question does not have enough trail in its fork?
09-10-20, 09:05 AM
#72
Senior Member
Join Date: Apr 2011
Location: Alpharetta, GA
Posts: 15,280
Bikes: Nashbar Road
Mentioned: 71 Post(s)
Tagged: 0 Thread(s)
Quoted: 2934 Post(s)
Liked 341 Times
in
228 Posts
Or downgrade the wheels :-) There is no reason to believe a more expensive wheel will excite the resonant frequency of the any less than a cheaper one. Id try a balanced wheel with an other weight. But then again, that may just alter the resonant frequency of the system, and push the wobble to a slightly different speed.
We don't actually know if the wheels have anything to do with it, in a given incident. I think that speed wobble arises from incidental combinations of practically any structural or moving components and/or the rider reactions.
09-10-20, 10:06 AM
#73
Senior Member
I believe the issue is the undampened nature of the fork that is at the root of the problem. It has been know in MCs for decades and all sorts of dampeners are available, both oem and after market. Cane creek has a dampened headset for bicycles, but it wont fit most road bikes.
https://canecreek.com/product/viscoset/
https://canecreek.com/product/viscoset/
09-12-20, 08:57 AM
#74
Advocatus Diaboli
Join Date: Feb 2015
Location: Wherever I am
Posts: 8,633
Bikes: Merlin Cyrene, Nashbar steel CX
Mentioned: 14 Post(s)
Tagged: 1 Thread(s)
Quoted: 4731 Post(s)
Liked 1,531 Times
in
1,002 Posts
But i think the question is, if you had a friend of yours try that bike, do they also have the same problem?
09-12-20, 11:21 AM
#75
Full Member
Join Date: May 2009
Location: WI
Posts: 262
Bikes: 2010 Bob Brown Cycles tandem, 2019 Co-Mo Carrera tandem, 1980 Richardson tandem, 2014 Cervelo R3, 2018 Specialized Roubaix, 1985 Bianchi Campione, 1983 Trek 720, 2020 Trek Fuel EX8, 2021 Salsa Mukluk
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 72 Post(s)
Liked 116 Times
in
70 Posts
Of course, I wouldn't be able to answer that question with any certainty unless we actually did the test for real, but my hunch is that the bike would indeed go into a "shimmy" of sorts if another tandem team took it to a high enough speed for it to occur.