Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Crissa]

Okay, so my bike got dropped while I was away.  Spouse is okay, but embarrassed.  https://www.electricmotorcycleforum.com/boards/index.php?topic=9705.0

Now, the handbars and entire console and forks were crooked to the front wheel.  It didn't seem hazardous, less than ten degrees or so, and you can't ride with the wheel not aligned, because it has gyroscopic force.  But I couldn't figure out how that could be; the handlebar was straight to the console and forks.  Only while riding I realized the entire front, headlight and forks, were turned slightly to the right.  Also I couldn't get it into the lock position, though my spouse could.

Once somewhere flat and warm I looked at it and then just stuck the wheel between my legs and wrenched on the handlebars until they were straight.  Then drove the curvy way home and it was happy.

But what was wrong, and what's the *right* way to fix it?  'Cause that seems entirely the wrong way to do it.  But the handlebar lock is smoother than it was before the wreck now!

-Crissa

[TheRan]

My guess would be that the upper and lower fork crowns (that's what they're called on mountain bikes, I think people might call them yokes on motorcycles) got misaligned, causing the fork legs to no longer be parallel. The correct procedure for straightening things back out on a mountain bike (which should transfer over well to a motorbike), assuming the crowns and fork legs haven't been permanently deformed, would be:

-loosen up all bolts, everything at the axle, pinch bolts on the crowns that clamp around the legs, and the nut that compresses the bearings in the head tube by pushing down on the upper crown
-clamp the fork legs in either the upper or lower crown, making sure they're the same distance from the top of the leg. If the crown isn't bent the legs should end up being parallel
-tighten the bolt to compress the head bearings
-tighten the pinch bolts on the remaining crown. If it's the upper crown you can lift it off the top of the fork legs and it should slide back on easily, if you need to force the legs to align them with the holes then something is probably bent.
-tighten the axle

EDIT: My theory would be backed up by it not being easy to put the steering lock on. How far you can turn the fork is determined by the lower crown, but the locking bolt goes into the upper crown. Twist the upper crown one way and it won't go far enough to one side for the bolt to slide in, however it should still go in with the forks turned in the opposite direction (most bikes allow this, haven't actually tried with the Zero though).

[Crissa]

Wow, sounds complicated.

Also, I don't know what a crown is. x-x  I've never had to fix the forks on my mountain bike.  Tho one is leaking, so that's going to happen soonish.

-Crissa

[TheRan]

The crowns are the bits that clamp around the fork legs, the mudguard bolted to the lower one and the bars mounted to the upper (and I think the headlamp is probably bolted to both). The lower has the steerer tube attached to it which runs up through the headtube of the frame like a massive bolt and then a large nut sits on top of the upper crown to squeeze everything together.

[Richard230]

That should work, but also check to make sure that your handlebars are not bent.  I have always referred to "yokes" on motorcycle forks as upper and lower "triple clamps".

[Fran K]

Triple clamps, they clamp two fork tubes and the steering stem.  Although the steering stem isn't clamped like the fork tubes.  Often the steering stem, has a nut and bearing on top of the steering tube of the frame and then another nut on top of the upper clamp.  Generally one loosens up like described above and twists in the desired direction and see if it was enough.  To get it back without loosening stuff, on a street bike seems a bit easy.

If you take wheel off and rotate the lower fork tube you might be able to tell if it wanders.  Depending on whether it is conventional or upside down forks results might  vary.  generally a bend is near where the single pipe is next to where one pipe or tube is inside the other.

[BrianTRice@gmail.com]

I've performed fork straightening before, and it's easier than the jargon makes it sound.

I've got this little stub of an article but it could use some help: https://zeromanual.com/wiki/Gen2/Triple_Clamp

And this article is a reasonable procedure and includes torque specs: https://zeromanual.com/wiki/Fork_Oil_Change_and_Spring_Replacement

So, I'll be creating a Fork Alignment procedure from this thread shortly.

[Crissa]

How do I tell if the handlebars are bent?

Spinning a straight cylinder makes sense; but the handlebars aren't a straight object.

-Crissa

[TheRan]

If everything else is straight then you can measure from the end of the bars to an identical point on each side of the fork, say a bolt that holds the fender on or one that clamps the axle. Measure to multiple points just in case it's bent in a way that the distance to one point is still the same but different to another. This is what I did with my old bike when it slid on its side, turned out the left side of the bars (which it landed on) was about 1cm higher than the right. Not a big enough difference for me to feel (still rode on it for months until finding a replacement) and not that easy to see visually either. Of course when doing this make sure your bars are centred in the clamps too, measure from the end to the clamp and make sure the distance is the same either side.

[ESokoloff]

Try this.....

[Crissa]

Thanks guys, this has been really helpful!

-Crissa