Notices
General Cycling Discussion Have a cycling related question or comment that doesn't fit in one of the other specialty forums? Drop on in and post in here! When possible, please select the forum above that most fits your post!

Resonance danger

Old 04-10-24, 09:11 PM
  #1  
Senior Member
Thread Starter
 
Join Date: Mar 2021
Posts: 2,020
Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 2738 Post(s)
Liked 490 Times in 355 Posts
Resonance danger

Hey guys, have you ever had your bike start to vibrate rhythmically? Normally I’ve seen this when riding without hands, and the handlebars start to shake and can quickly escalate into something dangerous. I think of this as resonance, and was very happy that my carbon road bike doesn’t seem to exhibit it, but after a few trips to the shop it now has developed a resonance.

Can someone who knows what I’m talking about expand on the phenomenon and suggest recourse, other than holding onto the handlebars?

thanks.

Last edited by LarrySellerz; 04-11-24 at 11:54 AM.
LarrySellerz is offline  
Old 04-10-24, 09:35 PM
  #2  
Senior Member
 
Yan's Avatar
 
Join Date: Jan 2006
Posts: 2,964
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 2028 Post(s)
Liked 674 Times in 461 Posts
Only on a four pannier touring bike that had too much weight in the rear and not enough in the front.
Yan is offline  
Old 04-10-24, 09:47 PM
  #3  
LR÷P=HR
 
Join Date: Sep 2019
Location: SF Bay Area
Posts: 2,225

Bikes: 1981 Holdsworth Special, 1993 C-dale MT3000 & 1996 F700CAD3, 2018 & 2019 Cervelo R3’s & 2022 R5, JustGo Runt, Ridley Oval, Kickr Bike 8-)

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 886 Post(s)
Liked 1,235 Times in 714 Posts
It’s likely a speed wobble

Barry
Barry2 is offline  
Old 04-10-24, 10:24 PM
  #4  
Grupetto Bob
 
rsbob's Avatar
 
Join Date: Sep 2020
Location: Seattle-ish
Posts: 6,411

Bikes: Bikey McBike Face

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 2674 Post(s)
Liked 5,902 Times in 3,031 Posts
The times it has happened to me, I was going over 40 MPH. Certainly gets your attention.
__________________
Road 🚴🏾‍♂️ & Mountain 🚵🏾‍♂️







rsbob is offline  
Likes For rsbob:
Old 04-10-24, 11:06 PM
  #5  
Senior Member
 
50PlusCycling's Avatar
 
Join Date: Mar 2018
Posts: 1,161
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 563 Post(s)
Liked 870 Times in 431 Posts
On motorcycles its called “death wobble.” I’ve experienced it on both motorcycles and bicycles, and it can be a little hair-raising. There are some things you can do to minimize risk, make sure your headset isn’t loose, the axle bearings aren’t too worn, and balance your front wheel. Wheel balancing is easy. Put your bike in a stand and rotate your front wheel, let it turn freely, and see if the same side always comes to the bottom. Take a bicycle computer magnet, the kind which attaches to a spoke, and put it on a spoke on the opposite end. You can move the magnet up or down the spoke to change its effect on balance. The wheel is in balance when you can spin it, and it stops in any position randomly.
50PlusCycling is offline  
Likes For 50PlusCycling:
Old 04-10-24, 11:06 PM
  #6  
Senior Member
 
Join Date: Jul 2009
Posts: 6,055

Bikes: Colnago, Van Dessel, Factor, Cervelo, Ritchey

Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 4010 Post(s)
Liked 7,517 Times in 3,025 Posts
Putting your fingers in your ears should stop the resonance.
tomato coupe is offline  
Old 04-11-24, 03:04 AM
  #7  
Senior Member
 
Ghazmh's Avatar
 
Join Date: Jan 2014
Location: The banks of the River Charles
Posts: 2,030

Bikes: 2022 Salsa Beargrease, 2020 Seven Evergreen, 2019 Honey Allroads Ti, 2018 Seven Redsky XX, 2017 Trek Boon 7, 2014 Trek 520

Mentioned: 19 Post(s)
Tagged: 0 Thread(s)
Quoted: 696 Post(s)
Liked 910 Times in 487 Posts
Is this the same bike with the tire where the bead has separated from the sidewall?
Ghazmh is offline  
Old 04-11-24, 04:07 AM
  #8  
Full Member
 
Join Date: Mar 2013
Location: Albany, NY
Posts: 461

Bikes: Trek FX 7.3, Specialized Roubaix, Orbea Terra, Aostimotor S17 ebike, Huffy RedRock (first bike)

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 226 Post(s)
Liked 346 Times in 154 Posts
Originally Posted by LarrySellerz
...but after a few trips to the shop it now has developed a resonance...
Why not go to the "shop" but in reverse?
XxHaimBondxX is offline  
Old 04-11-24, 06:51 AM
  #9  
Senior Member
 
Join Date: Aug 2009
Posts: 1,871
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 523 Post(s)
Liked 685 Times in 400 Posts
Does it happen when you see the chemtrails?...
wheelreason is offline  
Likes For wheelreason:
Old 04-11-24, 07:26 AM
  #10  
Full Member
 
awac's Avatar
 
Join Date: Oct 2022
Location: UK, New Forest
Posts: 280

Bikes: 1980 Gitane sprint,1977 Motobécane C4, 1977 Carlton Clubman, 1959 Claud Butler European

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 75 Post(s)
Liked 128 Times in 84 Posts
Originally Posted by 50PlusCycling
On motorcycles its called “death wobble.” I’ve experienced it on both motorcycles and bicycles, and it can be a little hair-raising. There are some things you can do to minimize risk, make sure your headset isn’t loose, the axle bearings aren’t too worn, and balance your front wheel. Wheel balancing is easy. Put your bike in a stand and rotate your front wheel, let it turn freely, and see if the same side always comes to the bottom. Take a bicycle computer magnet, the kind which attaches to a spoke, and put it on a spoke on the opposite end. You can move the magnet up or down the spoke to change its effect on balance. The wheel is in balance when you can spin it, and it stops in any position randomly.
In the UK it is also called a “Tank-Slapper” on motorcycles (handlebars slapping the tank). It is not a pleasant thing….
awac is offline  
Likes For awac:
Old 04-11-24, 07:31 AM
  #11  
Senior Member
 
Join Date: Jan 2013
Posts: 2,710

Bikes: too many sparkly Italians, some sweet Americans and a couple interesting Japanese

Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 572 Post(s)
Liked 605 Times in 419 Posts
Was this on the bike you said on 4/8/24 "My back tube popped (tire is worn out so not going to try and replace tube) right as I was leaving work, I have to ride 6.5 miles home and then another 6.5 miles back to work before I can realistically fix it. I don’t think I have a narrow enough tire at home. It feels like a bucking bronco but it’s nothing unmanageable if I keep the speed down, luckily it’s just the back tire."?
easyupbug is offline  
Likes For easyupbug:
Old 04-11-24, 07:36 AM
  #12  
Senior Member
 
Bald Paul's Avatar
 
Join Date: Sep 2017
Location: Upstate SC
Posts: 1,738
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 842 Post(s)
Liked 1,696 Times in 798 Posts
Originally Posted by LarrySellerz
Can someone who knows what I’m talking about expand on the phenomenon and suggest recourse, other than holding onto the handlebars?
Every time I read one of your posts, my hope for humanity dwindles.
Bald Paul is offline  
Likes For Bald Paul:
Old 04-11-24, 07:59 AM
  #13  
LR÷P=HR
 
Join Date: Sep 2019
Location: SF Bay Area
Posts: 2,225

Bikes: 1981 Holdsworth Special, 1993 C-dale MT3000 & 1996 F700CAD3, 2018 & 2019 Cervelo R3’s & 2022 R5, JustGo Runt, Ridley Oval, Kickr Bike 8-)

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 886 Post(s)
Liked 1,235 Times in 714 Posts
Originally Posted by wheelreason
Does it happen when you see the chemtrails?...
Yes, it will still happen.
But I’ve heard covering your helmet with aluminum foil can reduce the severity.

Barry
Barry2 is offline  
Likes For Barry2:
Old 04-11-24, 08:53 AM
  #14  
Senior Member
 
Steel Charlie's Avatar
 
Join Date: Apr 2009
Posts: 1,000
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 404 Post(s)
Liked 595 Times in 308 Posts
Steel Charlie is offline  
Likes For Steel Charlie:
Old 04-11-24, 08:58 AM
  #15  
Senior Member
 
Join Date: Sep 2007
Location: Far beyond the pale horizon.
Posts: 14,355
Mentioned: 32 Post(s)
Tagged: 0 Thread(s)
Quoted: 4312 Post(s)
Liked 1,387 Times in 967 Posts
Originally Posted by LarrySellerz
Hey guys, have you ever had your bike start to vibrate rhythmically? Normally I’ve seen this when riding without hands, and the handlebars start to shake and can quickly escalate into something dangerous. I think if this as resonance, and was very happy that my carbon road bike doesn’t seem to exhibit it, but after a few trips to the shop it now has developed a resonance.

Can someone who knows what I’m talking about expand on the phenomenon and suggest recourse, other than holding onto the handlebars?

thanks.
The "<bike> shop" didn't make it happen.

Did you know there are ways of searching for stuff on the intertubes?

https://velo.outsideonline.com/road/...-to-stop-them/
njkayaker is offline  
Old 04-11-24, 09:24 AM
  #16  
Klaatu..Verata..Necktie?
 
genejockey's Avatar
 
Join Date: May 2007
Location: SF Bay Area
Posts: 18,227

Bikes: Litespeed Ultimate, Ultegra; Canyon Endurace, 105; Battaglin MAX, Chorus; Bianchi 928 Veloce; Ritchey Road Logic, Dura Ace; Cannondale R500 RX100; Schwinn Circuit, Sante; Lotus Supreme, Dura Ace

Mentioned: 41 Post(s)
Tagged: 0 Thread(s)
Quoted: 10555 Post(s)
Liked 12,148 Times in 6,218 Posts
I got that once years ago my my Ritchey, coming down a short but fast non-technical descent. I hit 40 and the bike started wobbling and scared the hell out of me. I think it was the first time I'd gotten over 40 on it. I had only had the "5 Minute Fit". I took it in for a professional fit, where he dropped the bars, raised the saddle and moved it forward, which balanced my weight better, and it never recurred. I always credited the fit for solving the problem, but years later I read that wobble can be more of a random thing.
__________________
"Don't take life so serious-it ain't nohow permanent."

"Everybody's gotta be somewhere." - Eccles
genejockey is offline  
Old 04-11-24, 10:31 AM
  #17  
Full Member
 
Join Date: Oct 2023
Posts: 239
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 101 Post(s)
Liked 200 Times in 119 Posts
Originally Posted by genejockey
I got that once years ago my my Ritchey, coming down a short but fast non-technical descent. I hit 40 and the bike started wobbling and scared the hell out of me. I think it was the first time I'd gotten over 40 on it. I had only had the "5 Minute Fit". I took it in for a professional fit, where he dropped the bars, raised the saddle and moved it forward, which balanced my weight better, and it never recurred. I always credited the fit for solving the problem, but years later I read that wobble can be more of a random thing.
I think there are any number of factors that can initiate a speed wobble - road surface ruts, loose headset, unbalanced front wheel, etc - however, whether or not this relatively small input propagates/amplifies into a full-scale wobble is due to different factors, like F/R balance, "death-grip" on the bars, frame flex etc - factors that promote system resonance.. Some frames and rider positions are just more prone to wobble, some just aren't, even if they're traveling on the same roads and descending the same hills. Rider setup can be modified, but some frames will always be wobble-prone, IMO.
13ollocks is offline  
Likes For 13ollocks:
Old 04-11-24, 11:40 AM
  #18  
Senior Member
 
Steel Charlie's Avatar
 
Join Date: Apr 2009
Posts: 1,000
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 404 Post(s)
Liked 595 Times in 308 Posts
Too much weight forward of the steering center.
Steel Charlie is offline  
Old 04-11-24, 11:56 AM
  #19  
Senior Member
 
79pmooney's Avatar
 
Join Date: Oct 2014
Location: Portland, OR
Posts: 12,986

Bikes: (2) ti TiCycles, 2007 w/ triple and 2011 fixed, 1979 Peter Mooney, ~1983 Trek 420 now fixed and ~1973 Raleigh Carlton Competition gravel grinder

Mentioned: 131 Post(s)
Tagged: 0 Thread(s)
Quoted: 4865 Post(s)
Liked 4,013 Times in 2,608 Posts
Speed wobbles. 13ollocks describes them well. It is an oscillation caused by a driving force (that can be as simple as road vibration) and a system (Bike, wheels and rider) with a resonance of the same frequency (or harmonic of it). And it can vary from a minor scare to terrifying and high speed crash causing.

The cause is usually a combination of a particular bike and a particular rider. Sometimes simple changes are a permanent fix. Two things a rider should be aware of, one as a frequent cause of the wobbles and the other, usually a quick fix - the death grip on the handlebars; back off! Firm but NOT rigid! And the preventative/quick fix; place your knee on the top tube. That usually has a very large damping effect on the wobble.

I have one bike with the issue. Sadly my best custom that fits and rides like a dream. Recently I did a fast descent that while not absurdly fast, I have had to back off for the wobbles on the past. Tried lifting my butt a little off the seat with my legs a little more tensed, hands firmly in the drops with real weight on them and the bike stayed quiet. Haven't yet gone to the really fast hills trying that but I see that experience as encouraging.
79pmooney is offline  
Likes For 79pmooney:
Old 04-11-24, 12:16 PM
  #20  
climber has-been
 
terrymorse's Avatar
 
Join Date: Dec 2004
Location: Palo Alto, CA
Posts: 7,257

Bikes: Scott Addict R1, Felt Z1

Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 3554 Post(s)
Liked 3,715 Times in 1,862 Posts
Originally Posted by 50PlusCycling
On motorcycles its called “death wobble.” I’ve experienced it on both motorcycles and bicycles, and it can be a little hair-raising. There are some things you can do to minimize risk, make sure your headset isn’t loose, the axle bearings aren’t too worn, and balance your front wheel. Wheel balancing is easy. Put your bike in a stand and rotate your front wheel, let it turn freely, and see if the same side always comes to the bottom. Take a bicycle computer magnet, the kind which attaches to a spoke, and put it on a spoke on the opposite end. You can move the magnet up or down the spoke to change its effect on balance. The wheel is in balance when you can spin it, and it stops in any position randomly.
I doubt balancing a bicycle wheel will do anything to prevent speed wobble.

Originally Posted by 13ollocks
I think there are any number of factors that can initiate a speed wobble - road surface ruts, loose headset, unbalanced front wheel, etc - however, whether or not this relatively small input propagates/amplifies into a full-scale wobble is due to different factors, like F/R balance, "death-grip" on the bars, frame flex etc - factors that promote system resonance..
Add shivering to the list. The only time I've experienced speed wobble, descending Montebello Road when it was snowing.
__________________
Ride, Rest, Repeat. ROUVY: terrymorse



Last edited by terrymorse; 04-11-24 at 12:21 PM.
terrymorse is offline  
Likes For terrymorse:
Old 04-11-24, 06:40 PM
  #21  
The Wheezing Geezer
 
Fredo76's Avatar
 
Join Date: Oct 2021
Location: Española, NM
Posts: 1,098

Bikes: 1976 Fredo Speciale, Rivendell Clem Smith Jr., Libertas mixte

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 423 Post(s)
Liked 993 Times in 471 Posts
Originally Posted by terrymorse
Add shivering to the list. The only time I've experienced speed wobble, descending Montebello Road when it was snowing.
I'll believe that in a heartbeat.

Muscle tremors from other causes (nerve-related or due to exhaustion) are suspect too.

Climbers sometimes suffer from what they call "sewing-machine leg", which is no fun, either.
Fredo76 is offline  
Old 04-11-24, 07:17 PM
  #22  
Senior Member
 
79pmooney's Avatar
 
Join Date: Oct 2014
Location: Portland, OR
Posts: 12,986

Bikes: (2) ti TiCycles, 2007 w/ triple and 2011 fixed, 1979 Peter Mooney, ~1983 Trek 420 now fixed and ~1973 Raleigh Carlton Competition gravel grinder

Mentioned: 131 Post(s)
Tagged: 0 Thread(s)
Quoted: 4865 Post(s)
Liked 4,013 Times in 2,608 Posts
Originally Posted by terrymorse
I doubt balancing a bicycle wheel will do anything to prevent speed wobble.



Add shivering to the list. The only time I've experienced speed wobble, descending Montebello Road when it was snowing.
Yup. And aging. Or, one of the best preventions is confidence. My bike that wobbles - only showed up once early on. On a cold ride with rain. Now, out of my early 50s and into my 70s, it is far worse. I carry warm clothes and stop and put them on for big descents even though I'll be on nice warm level ground in 10 minutes. On my other, non-wobble bikes I dress the compromise between comfort and convenience.
79pmooney is offline  
Old 04-11-24, 09:41 PM
  #23  
Senior Member
 
Sierra_rider's Avatar
 
Join Date: Mar 2023
Location: NorCal
Posts: 593

Bikes: Santa Cruz Blur 4 TR, Canyon Endurace cf sl, Canyon Ultimate cf slx, Canyon Strive enduro, Canyon Grizl sl8

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 245 Post(s)
Liked 1,060 Times in 405 Posts
One of my road bikes is particularly susceptible to speed wobbles. I attribute it mostly to the 50mm wheels, as it will only start to pick up a shimmy at speeds above 40mph, with battling winds present. In dead calm conditions, I've confidently had that bike nearly to 60 w/o issue. I've tried changing my contact points when it starts to happen and keep a light touch on the bars, but nothing seems to fix it other than dropping below 40. Oddly enough, my other road bike with different 50mm rims, doesn't have the same issues. I can feel the wind pushing the bike, yet it doesn't develop the shimmy.
Sierra_rider is offline  
Old 04-11-24, 10:04 PM
  #24  
Senior Member
 
Join Date: Dec 2004
Posts: 1,156
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 618 Post(s)
Liked 709 Times in 423 Posts
A Resonance Cascade occurs when a Negative Mass Crystal is scanned by an Anti-Mass Spectrometer.

Although I will admit that the possibility of a resonance cascade scenario is extremely unlikely, I remain uncomfortable with the...
CrimsonEclipse is offline  
Old 04-11-24, 10:13 PM
  #25  
Senior Member
 
zandoval's Avatar
 
Join Date: May 2010
Location: Bastrop Texas
Posts: 4,561

Bikes: Univega, Peu P6, Peu PR-10, Ted Williams, Peu UO-8, Peu UO-18 Mixte, Peu Dolomites

Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 1000 Post(s)
Liked 1,680 Times in 1,079 Posts

So... Speed Wobble...
Front Brake or Back Brake?


As I remember on a Motorcycle it was feather the back brake...
__________________
No matter where you're at... There you are... Δf:=f(1/2)-f(-1/2)
zandoval is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.