Shuttering Fork Problem
 

So I built my first single speed conversion and posted a pic up on the "show Pics" forum.(it's the flat black and green one) It's a lot of the same 1970's Royce Union 10 speed parts. I put on a front brake and when I'm cruising and try to come to a hard stop, the front fork shutters and jolts. feels firm, and safe, but isn't really cool. the bike has the original fork, 27inch wheels, brake. Anyone had similar experiance or a way to fix it? Let me know!
kirk

headset is loose.

ding ding ding!

I third the motion. Also, is it possible that you were so excited to complete the build that you didn't adequately tighten your front wheel nuts, causing them to come loose after a few rides? Don't laugh; it's happened to me. I mean, to a friend.

My current ride is a thrift-shop Schwinn Caliente that I converted and I have the same issue. The headset checks out fine. I think the fork is too flexy on this cheap frameset. Seem familiar?

Did you replace the stem when you did the build...or is the stem very short? Sometimes, a short stem - which puts the handlebar clamp behind the front hub can cause shimmying motion when you ride. If this is in fact the problem, you may notice a similar shimmying when you get th bike up to higher speeds - 20mph or so.

The headset will seem fine upon inspection, grab the front brake and wobble the bike backwards and forwards to check it out. TIghten until it flexes as one when the front brake is engaged

If it displays those symptoms when braking on smooth ground, then it sounds like a flexy fork.

also it could be the brake is installed inproperly. I really doubt the fork is so flexy it feels like "shuttering".

Yeah could be the brake shoes, but these are also common symtoms of really lightweight or cheap forks.

Agreed. I've got a cheap (Weyless) carbon fork on my road bike that shutters occasionally under braking load. Disconcerting, to say the least.

I'm too lazy to go look at the bike to see if he used new wheels, but there's also the chance that this is from dinged up or slightly warped rims if they're old. But I give that a 10% chance behind 50% loose headset and 40% jingus brake install. Plain old fork shudder I wouldn't expect from steel.

New correctly toed in brakepads and a clean rim and then check out the rest of the theories.

If the rims and brake shoes are new they just need a chance to break in a bit. I put together a Crosscheck with a Winwood carbon cyclocross fork and Avid mini canit's. When I took my first test ride the thing shuddered so severely that it was unrideable. But everything worked out in the end and it's an excellent set-up. Well, I did switch over to V-brakes. But that's another thread, eh.

Take some medium sand paper to the pads and toe them in then just take it easy for a few miles.

DanO

Hopefully you've been able to solve your bike problem by now. But if you haven't, I suspect your brake caliper is the culprit or a couple of things are. You probably removed the caliper and simply masked off the headset when you painted it, right? You might have done something then. Also, are those weinmann centerpulls?
Check what's loose with this test:
Squeeze the brake and try to push the bike forward. Rock it back and forth a little and feel for play. Either way, if the calipers are loose (a different problem than old, oxidized pads) or the headset is loose, you should feel some slop. Headset play will tend to be more abrupt, as the steerer tube of the fork moves from the back to the front of the head tube of the frame. bUt don't worry too much about trying to diagnose it from this one test. Now turn the wheel ninety degrees so it's perpendicular to the frame. Push the frame back and forth again, but this time without squeezing the brake. The sideways wheel should prevent the bike from rolling forward, while allowing you to test the headset exclusively. I like to put my hand on the bottom cup of the headset, as I can very easily tell if there's play there where the fork comes out of the frame.

Hopefully this will indicate where the problem is. Not unusual for dumpstered bikes to have a couple of things wrong with them. If everything's tight, check out that wheel. Did you spraypaint the rims? It looks a little like that from the picture.

And just out of curiosity, how's it ride with no hands?

Good luck.
-Austin

maybe improperly adjusted axel cone nuts, just a wild guess=p

ok gentlemen, so I've been trying some stuff out and the head is extremely tight. Also the stem is a 3ttt stem that is definetely long enough. I need to check out the idea that the brake caliper might be loose, but I definately feel play when i lock up the front brake and rock it.......I just can't seem to identify visually, everything looks ok...the "play" feels like the fork is too skinny for the frame by a milimeter, but it's the same fork that was on the bike originally. I'm leaning toward the idea that it's a cheap fork...here's another clue, sometimes the brake will squeel when it shutters, I thought this was because I still had the disgusting brake pads on it from when I found the bike....I just sanded them down to get some new rubber on the rim. Now I'm thinking it might have something to do with this.

Funny, that the post before I posted pictures of my bike on the pic forum, was a guy all pissed off about seeing kids riding ghetto fixed gears.....sounds like he has too much money on his hands....

GET NEW PADS.... but first:

Put your finger by where the headset and headtup meet. if the cups are moving your headtube is ovalized and your ****ed. The kludge would be to get a new headset and have it jbwelded into place but thats not really worth it on this bike.

If there is no play there try between the crown and the cup and between the top headset parts. If there is play here you may have reinstalled the headset incorrectly.

I think you missed his point. I don't think he had a problem with ghetto fixed gears. Single speed freewheel bikes which have only one brake to depend on to stop, makes a few people nervous. Its like putting all your eggs in one basket.

But some people feel the same way about fixed gears with no brakes other than your drivetrain, no matter how long you've ridden that way or how experienced you think you are.

Drop test:

Lift the front wheel of your bike up about 6 inches of the ground.
Drop it and let it bounce. If the fork makes a stuttering sound it's
most likely a loose head set.

You say it's an old bike?
Either be cheap and just tighten your headset.
Or be nice and repack your headset with new
bearings and lots of grease. Tighten it to the point
where you can steer freely from side to side and
when you do the drop test it doesn't stutter.

People have mentioned loose brakes, crappy brakes, and loose cones. All of which are valid.
Everything must be tight and greased! EVERYTHING!!!!!!!!!!!!

If it was someones beater b4 you got it & it had a hard life then the headtube may be ovalized from a collision or hard braking with a loose headset. Hopefully it's your brakes in that case because you can't tighten a headset in an ovalized headtube, it'll shudder anyway