I have new wheels, new skewers. I have tried switching the watch to the left side of the bars without any success.. Could the weight of the skewer cause this?? I do go full send on this bike on the trails and have crashed it a lot. Could it be fork damage? Of note: pedaling stops the shudder.
Do you guys have any idea what is causing this?
byu/Zestyclose-Rhubarb38 inbikewrench
by Zestyclose-Rhubarb38
40 Comments
are you running tubeless ?
is there any lateral play in the wheel?
This is common when the headset is loose.
OP: I hope you get it sorted; but my first thought was “your bike’s just vibing”
I’d actually opt for something with the wheel. Check spoke tension, wheel truing, bearings etc
>I do go full send on this bike on the trails and have crashed it a lot.
Check your headset, check your wheels and quick release. Read up on shimmy and wobbles
https://www.sheldonbrown.com/shimmy.html
https://velo.outsideonline.com/road/road-training/bicycle-speed-wobbles-how-they-start-and-how-to-stop-them/
Check all bolts
Loosen stem bolts and tighten down compression cap
Check that wheels are true and don’t have heavy spots
Check for any areas of play
Lots of things can cause death wobble. Make sure your headset is tight, the wheel is installed properly, the wheel bearings are seated properly, and the fork is undamaged and perfectly aligned. The main cause of death wobble is something loose causing the front end to oscillate. Pedaling stops the death wobble because you are preventing the system from reaching its resonant frequency.
I had this problem in one of my bikes and rabbit-holed on the internet. It’s a really common problem called ‘speed shimmy,’ ‘death shimmy’ or ‘high speed shimmy.’ Basically, there something in the system that is hitting a frequency that grows, similar to a tuning fork.
The problem is that the general definition above can come from a whole variety of sources and that is why people call it “mysterious”: a loose headset, wheel asymmetry, unevenness in a brake pad.
One thing that was helpful for me was differentiating the “source” (the originating thing) from “the condition that allows it to grow.” For instance, a loose headset might be the source, but the fact that the bike is loaded in the rear much more than the front is what allows that source to grow. A lot of people report loading the bike differently to load the front more – shifting the rider closer to the bars, putting a bag on the front, or even temporarily putting your leg on the top tube when you start feeling the shimmy – as sort’ve a catch-all solution, but it does not eliminate the “source.” Goodluck.
Those hoods…
Oof, Tank slapper, speed wobble, gyroscopic precession and resonance are the terms you’re looking for.
Has a multitude of causes, weight balance, misalignment of parts, loose bits and many more things.
First step, undo and re-torque EVERYTHING to spec, particularly headset and hubs.
Second, Wheels and tyres, check spoke tension and true, check tyres and reseat ensuring the bead seats correctly everywhere.
Thirdly, get a set of old school balance scales and place each part of the bike on it and weigh it against 1 pound of fresh willow bark, ignite the bark and pray to the gods of balance for a solution, preferably whilst riding a goat.
Finally take it to a shop, only after thoroughly attempting step three.
If you have followed all the useful tips provided here in this thread and still have this issue, it could well be a geometry problem. It is usually not something that will occur when the front end of the bike is loaded (IE hands on the bars) but will occur if you sit upright at decent speed.
Had this happen when I switched to wider, heavier handlebars. I’ve read that the weight distribution up top can throw the physics out of whack.
Shimmy is a complicated thing. It could have all sorts of causes or contributing factors. It is typically not dangerous if holding the handlebars quells it.
A common way to reduce it is to add friction to the headset interface. Slightly tightening your headset might accomplish this, but the best way is to get a needle bearing headset which has more friction by design.
I’ve only experienced this to any degree on one of my old bikes that was extremely low trail — 29mm (regular trail numbers are 50mm+) and it shimmied a LOT. This is how I learned about needle bearing headsets and yes, that worked.
Weight distribution, loose bearings somewhere, bike design, cracks in the frame — these can all be factors.
If you need to ride no-hands and shimmy is bad, try resting a knee on the top tube. That could stop it temporarily.
It seems nervous….. Are you riding through the hood?
There’s a resonant frequency somewhere in your bike that matches vibration it picks up from the road.
This is the same phenomenon physically as a public address system squealing — ringing its called by engineers — when the microphone is in the wrong place.
A hand on the handlebar damps the shaking, probably instantly., by taking away the resonance.
What happens if you remove all that equipment, all secured by nice bouncy elastic straps, from the handlebars? The weight of that horn, especially, might be making the front fork / wheel / bars resonate.
Other than that. Dampen the wobble with a steady hand. Check for dodgy headset or front wheel bearings. Make sure the front wheel spins true and the tire is mounted correctly.
Building bikes, or any mechanical objects, so they don’t resonate like this , that’s what takes a long time to learn in mechanical engineering school.
Shimmy/Resonance as other folks have said. I’ve heard some folks say a shorter stem can be a contributing factor. But obviously you don’t want to compromise your fit/comfort so ymmv
Yeah, not uncommon when your rim is out of true, one or two crazy loose spokes from some trail hits.
True/tension the wheel and go again, let me know how it goes 🙂
You have to loosen the two stem bolts first, then tighten the headset (top bolt), then re-tighten the two stem bolts….
Death Wobble…. Jeep owner here
Check that no bolts are loose, that headset preload is good. If nothing is loose or amiss, sometimes death wobbles just happen when you have bad luck with your position on the bike, the bikes geometry, and your wheels. Its possible changing some of those variables might make it go away.
When this happens on motorcycles the advice is to “throttle out” or unload the front by speeding up. On a rigid fork I can’t think of anything compressible in the front other than the tires.
Are your pressures good? Do you have dry sealant caked in them? Too much sealant?
What’s your weight distribution? Are you front heavy?
Harmonic wind vortex formation and shedding, exactly what brought down the Tacoma Narrows bridge.
Caused by the aerodynamic interface between that goofy horn and that shit tape job.
maybe the horn is causing wind turbulence.
One thing that I know for sure, is that nasty bar tape isn’t helping
Could be [speed wobble](https://en.wikipedia.org/wiki/Speed_wobble). It’s a function of (among other things) bike geometry and rider weight and position, and input of lateral acceleration to the wheel (like a bump).
Your bike has terrible anxiety
Your bike has that Michael J fox disease
Tried moving the watch, what about the horn tho!!
Is that a jeep ? I believe they call that “death wobble”
FYI: grab your top tube with both knees. That should neutralize the wobble. You are effectively damping the oscillation and preventing harmonic resonance.
Speed wobble ,Wheel cold be out of true ,Hub loose ,Headset loose ,Wheel not in the dropouts right ,Quick release not tight ….Regrease your headset and tighten things down and try it out again .And your levers are all kinds of fucked up .
it is the vibration
Watch goes on the wrist not the bice Fred
It looks just like speed wobbles, a noted two wheel phenomenon.
You need to balance your wheels.
seatpost rear rack?
If the headset is tight i would check front hub
What is going on with your brake hoods angled in so aggressively?
Never seen a bike get death wobble only jeep wranglers and lifted trucks