Help! Bizarre steering issue
 

hi all --

I crashed my Bridgestone on a trail in May this year & initially thought it to be (luckily) entirely undamaged. however over the last few months, an issue has come to my attention with the steering & balance of the bike. The best I can explain it is that when the bars are centered/inline with the wheel, the bike feels unbalanced and has a tendency to lurch to the left, especially when turning at tighter angles or riding out of the saddle. initially i thought that the stem or handlebar must have been bent, but after replacing both parts I have found that the issue persists. For whatever reason, the bike steers the best when her bars are tilted about 5-7 degrees to the right of the front wheel!

So far I have replaced the stem, put on a new pair of drop bars, loosened the headset, TIGHTENED the headset, all to no avail. The wheel is centered in the fork and I am certain that it is seated in the dropouts. I have a short commute of 4mi round trip & refuse to pay for parking @ work, so I have just been toughing it out so far, but it's killing my drive to go on recreational rides with a bike that feels unstable and unpredictable. I am a decently experienced home mechanic, but have never encountered something like this before and don't understand how the bike could not steer straight even when the bars are in perfect alignment. I'm working on a frame-up build for another bike right now for other reasons, but I have room for only one and will need to diagnose/fix this issue before putting it up on Craigslist.

My suspects so far: a bent fork/steerer or crushed/worn ball bearings (original 1" headset, unsealed). Any ideas? Similar experiences?

Those symptoms after a crash definitely point to bent fork.

+1.

The bike doesn't care which way the bar or stem are pointed.

When a bike tracks to one side it's usually a bent fork. It could also be a bent rear triangle.

If you're super lucky, it might be that the front is pulled partway out of the dropout, but that would be only sligtly short of a mirricle.

Got a picture? Nothing like a bent fork to stir up the crowd.

that's the thing -- it's not visibly bent! I'll have to see if it's more obvious once it's off the bike but I don't have anything else to ride at the moment so I'll have to wait until I can find an inexpensive fork on ebay. Sorry to disappoint haha ;)

Picture and visually looking at it might not help you, but some here will be very familiar with how that fork and headset is supposed to look and they'll even draw lines on the pics you post to figure out what the angles of your fork and headtube are.

But if you don't want the help.......

...I wouldn't buy a fork on ebay, that you cannot return for a refund, unless I had a competent diagnosis of the problem.
Just pulling and replacing stuff at random is not the most effective way to address a mechanical issue.

It might be worth taking your bicycle to a professional at this point. Just a suggeston.

now I sure don't recall saying all that! :) Let me get my tenth post in here so it will let me post an image. No bend was visible while the fork was mounted although I have just taken it off the bike and suspect that the left blade is twisted, looking at it from a worm's eye view.

...this is what a fork alignment gauge looks like. You can see how it measures both centering, spacing, and alignment simultaneously. There are ways you can measure each of these things without the gauge, but if you need to straighten something, it's quicker and easier with a gauge.


https://cimg7.ibsrv.net/gimg/bikefor...ca2e2e5a76.jpg

https://cimg2.ibsrv.net/gimg/bikefor...88214a6ca8.jpg
https://cimg1.ibsrv.net/gimg/bikefor...5d4333ea5d.jpg
https://cimg8.ibsrv.net/gimg/bikefor...09f9e0d23b.jpg

well, go ahead and take a gander! The left dropout looks to be out of line, although it's close -- will have to call the shop & have them do more than eyeball it. I thiiiink the rear triangle is fine, attached a pic anyway -- although the bike fell on its left side with a basket & rack attached to the front cantilever posts so the fork explanation does seem more plausible. Thanks all for the input :)

I agree with the others who think of your fork as the primary cause of the problem. It could also be because of misalignment of the main triangle. Trying to fix this problem by changing stem and/or handlebars is akin to performing a colonoscopy by threading the endoscope down the patient's throat

If you have a piece of string (or yardstick) and ruler, you can do a quick (rough) check on the bike. Simply loop the string over the top tube and stretch down to the axle to establish a straight line. Then measure in to the crown on each side. If it's obviously off center, you know, if not, it's at least not bent badly.

You can't tell much from a photo that might incorporate lens distortion.

But the orientation of the handlebar will affect the steering and weight you apply through your arms, and your perception of steering pull.

I have a bike that does that - I slid off on diesel at fairly low speed and landed hard on my hip. There was no obvious damage to the bike but a few weeks later one of the pedal spindles sheered off, suggesting that it had hit hard. I've never pulled the bike apart to figure out exactly what was bent - it seems unlikely it would be the fork because it didn't really hit anything, so I'm guessing a twist between head and seat tube.

A couple ways a fork can be "bent" or twisted.
Rear triangle checking.
https://cimg8.ibsrv.net/gimg/bikefor...8a21ca6247.jpg
https://cimg1.ibsrv.net/gimg/bikefor...1185c4ca95.jpg
https://cimg9.ibsrv.net/gimg/bikefor...35b4e9df64.jpg

By your own admission the photo might be distorted. So that means there will be times when it's not and in that case with the proper camera position you can tell a lot and compare to other bikes of the same model. Even pictures of those bikes.

And believe it or not, with the really new fangled technology of the last 30 years we can remove or at least account for distortion with the better photo editing software we can get for our PC's and Macbooks.


However the OP didn't give just a profile pic of the bike with the fork installed as I was hoping for. I've seen several people come here to BF with pictures of a fork that is obviously bent or a bent downtube putting the headtube at the wrong angle and they'd swear themselves nothing looked odd. Even though it very much did when compared to a pic of the same model.

more like treating athlete's foot with an enema.

here's one in profile, and a close-up of where the fork meets the head tube. The bottom half of the headset is aligned fine and I don't see any obvious bend in the direction of travel or otherwise. the crash in question came from a loss of traction in loose dirt -- luckily, there was no front-on impact so i don't believe it was bent backwards at all?

https://cimg9.ibsrv.net/gimg/bikefor...67d487e7a1.jpg
https://cimg8.ibsrv.net/gimg/bikefor...b80dc63b9e.jpg

This topic, frame/fork alignment, has been discussed many times before. There's quite a number of threads one can search for. here's one from 2017 where I describe a low cost "home" alignment check. Bike Pulls to the Left - Bike Forums My post (#16) has photos of what I used to do before I got my surface plate and fork "vise". One doesn't need fancy tooling or expensive jigs to do this stuff. It does help to have a mind that is good at spatial relationships (round hole, round peg) and can be patient enough to let the awareness develop. Andy

There, fixed that. :twitchy::troll::roflmao2:

Humans are amazingly adaptable, and will very quickly compensate without even knowing they're doing so.

queenmildew I would bring it to your local shop or frame builder to check it over. Like others have said distortion can have an effect and something could be off and we cannot tell as easily without seeing it in person. If you had a crash and especially if you had issues resultant to that crash I would want a professional to look at it in person just in case especially on a bike like that. Bridgestone RB-T are good bikes and worth having checked over.

strangely... Listerine is a home remedy for Fungal infections... :thumb:

I think the steertube is bent forwards, from looking at the the lower headset. Did you experience any rotational binding in the fork rebuild? Very touchy rebuild?