sickz

so today i was comin' down a nice section of la cienega (los angeles) which is a regular hill i enjoy riding up, then back down.. combination of pressure crankin' to modulate my speed and a few bumps in the road sent my bike into some serious headshake (equivalent to a motorcycle when the bars start slapping back and forth).... my bike has relatively steep angles @ 75deg headtube and seattube (80s pinarello track).. which must have contributed to sendin' it into such a violent shake.. i attempted to ride this out for a few seconds and just gave in and went into a skid which stopped the shaking entirely.

if you wanna replicate it.. lift your front wheel up and set it back down w/ the wheel turned.. that'll give you an idea of what i'm talkin about.. only this was at 25+mph..

my question is.. anyone ever get shake this bad? and what have you done to combat it before hittin' the pavement... ?

also an excuse to post a pic of my bicycle...

akkando

I am new to bikes and have not had any problems yet but I eagerly await information on how to stop and prevent it.

However, I have had speed wobbles on my skateboard when I used to skate a lot coming down hills. Sometimes I could ride it out provided I was close to the bottom or not still picking up speed. Other times it resulted in a flying superman off the skateboard and eating ****.

Nice bike

fixedfun

There's your problem..
Ship the frame to me and get a kilo or something

captsven

Sounds like a bearing play issue.

Check your headset and front hub for play in the bearings.

coppertop4646

Use a brake

bbattle

Could be a loose headset but keep in mind track bikes were not designed to go anywhere but on the track.

LoRoK

Happens to me sometimes too. Feels like it's coming from the back of my front wheel, if that makes any sense. I figure it has something to do with geometry or fork rake and trail or something, but I really have no idea at all. I generally just power through it. It goes away once I get past the 26-27mph range. It doesn't happen when I'm doing high speeds, fortunately.

dutret

loose headset is possible but speed shimmies are pretty common on road bikes and often hard to fix. I guess they are less of a problem on fixies cause most people don't get above the mid-30s often.

My guess is your frame is slightly out of alignment(or the rear wheel was) and your COM is probably all ****ed up do to poor fit.

clink83

I'm going to take a stab that your jackassed too low stem and deep drops are negativly affecting your handling.

sickz

hmph.. i'm very aware of what causes headshake.. and just about every reason you guys have thrown at me is way off on another tangent...

headshake is caused when the front wheel makes contact w/ the road on a point which is not on the imaginary line of the bicycle's wheelbase... it's common in cases when you are leaned over a bit.. and hit a bump which causes your front end to get light.. and when weight is redistributed to the front... the wheel shakes trying to realign itself w/ it's natural line to the rear wheel... but anyways.... that wasn't my question...

and my stem is slammed for asthetics. yup. and i like it. at the track it gets raised up to make the drops more comfortable.. but all that is besides the point..

dutret

a misaligned or bent frame or rear wheel is not off on any tangent. I can almost guarantee it's a problem at the moderate speeds you're riding because your position on the bike is all ****ed for aesthetics.

sickz

i never stated that headshake consistently occurs when i hit a certain speed... you misread what i typed initially, entirely.

my frame is actually perfectly straight within .001 of an inch.. i measured it on a granite surface plate when it arrived via ebay... any other assumptions?

dutret

I didn't assume that frame alignment was the cause I just stated that it could be. Even then the fork could be bent but it's most likely that you just had the wheel in askew.

I stated that your idiotic bar set up is most likely responsible and I stand by that. I'm not saying that it will shimmy every time you get up to that speed but that it wouldn't have been a problem this time if your bike didn't belong in the jackass thread.

sickz

looks can be deceiving my friend.. my saddle to bar drop is 5inches to the bars center. and my fork is straight.. but thanks for the input. and yes i'm quite aware my bicycle isn't ergonomically friendly. but i've never had any soreness from riding it.. except in my legs after 40miles..

but yes the stem is too long... i could use a 90mm. w/ less neg angle... hence the 90mm jag steel as opposed to the 120mm jag alum that is currently on there.

dutret

oh so you were just gripping them by the stem? Gee I wonder why it was hard to control.

mihlbach

Where were you holding onto the bars when it happened...on the top or in the drop?

sickz

actually i was on the shoulders.

dutret

get some more appropriate bars for riding on the road.

sickz

that's what i have a roadbike for.. but i prefer my trackbike on short jaunts.

too many people assume riding a track bike w/ drops is such a radical stray from comfort when it's really not. perhaps you're just old, grumpy, and slow.

adriano 

lets get ready to rumble!

alheim

sickz, nice bike. be careful out there rolling brakeless at 25mph downhill. much traffic on that road?

tFUnK

i don't know which part of la cienega you were on but that stretch coming down sunset is real scary especially if you're brakeless.

i'm having a hard time imagining the "head shake"; all i experience are jolts caused by the *****ty road surfaces.

dutret

I never said you couldn't get drops but if you're not mainly riding in the drops and always doing so when you need control track drops are the wrong bars. Unwrapped track drops are always a jackass option anyway.

In my book if you can't keep your **** together enough that you're not forced to skid to a stop to avoid crashing you need to be changing something.

sickz

no i'm not mainly riding in drops.. and neither are roadies.. they're mainly riding on the hoods... therefore they should have bullhorns right?! i do get in the drops often enough to warrrant them... but that's besides the point.. and i ride w/ gloves... obviously you're a comfort guy, who adheres to such and never sacrifices such.

and yea la cienega comin' down from sunset is gnarly for the first stretch, but once you hit fountain it smooths out.. .i caught the wobble approaching santa monica.

clink83

No, we know how to properly fit a bike. You're just an idiot who has a problem, is then told what's wrong, and tells us were wrong. Talking to you is a waste of time, enjoy your tark bike. Hope that speed woble doesn't kill you since you're not smart nuff to run a brake. /end thread.