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Bent rim


electricpen
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So I had an unfortunate visit with the pavement today and the crack I hit was big enough and I was going fast enough that I have bent the rim on the wheel. It has a rhythmic thumping feel now as I ride around although it is probably not audible to others. I can just feel it as I ride. Does anyone know:

1) How hard it is to fix this?

2) How dangerous it is to ride on it like this?

Maybe this just means I need to buy a new wheel???

bent rim.jpg

Edited by electricpen
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Well it's always a good time to buy a new wheel. :) 

Since the wheel has an inner tube it's not like a car where the bead of the tire has to seal against the rim. Still, I would be very concerned about riding it that way. You might be able to bend the rim back close to where it should be by setting it on its side and using some sort of pointer barely touching the rim to check the rim runout. You won't get it to be perfect but it should be better than that!

 

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I'm probably going to try to straighten it myself. If that doesn't work - time to decide between an ACM2 and Tesla! This is forcing me to ride my mten3 more anyway which has been a little neglected. The accident that caused the damage was avoidable too. I was going down a hill pretty fast and saw this giant raised crack in the road. I've been practicing hopping over bumps and cracks and tried to jump it rather than slow down. I didn't get enough elevation and clipped the top of it at high speed and went flying. Even so, I almost controlled the landing but ended up in a controlled faceplant (class 2 according to the other thread...). Thank god for the flexmeter wristguards. I fully used my hands to brace my fall trusting the wristguards to work. Wrists are completely uninjured despite bearing the brunt of the fall.

Also, I didn't notice the sound/feeling right away after that incident so it actually could have been from one of my jumps later. I hop off curbs all the time so maybe it warped the rim a little and then me hopping off curbs a few times bent it out further until it looked like the picture above (there is another smaller bend on the opposite side of the wheel right under the valve. In any case I'll try fixing it tomorrow, thanks for the advice!

Edited by electricpen
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3 hours ago, electricpen said:

'm probably going to try to straighten it myself. If that doesn't work - time to decide between an ACM2 and Tesla!

 

Ugh! Cast aluminum rims are tough to straighten (reshape) unless you heat the area first. Beating the heck out of it will only weaken the casting. The downside is you will need to remove the tube/tire.

Slowly heat the bent region with a propane torch and then place the rim in good vise with wide jaws. Take your time squeezing the deformity back into shape. * Also place a leather glove (or any other non stick material) on either side of the rim to protect the rim’s surface. A wooden board would work. 

Go slow. Heat the rim a little bit at a time and slowly tighten the vise. The rim may not be perfect in the end but it will be hard to detect the deformity and most importantly the integrity of the cast aluminum will not be compromised.  

Edited by Rehab1
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36 minutes ago, Rehab1 said:

Slowly heat the bent region with a propane torch and then place the rim in good vise with wide jaws

The heating will work, but it is possible the magnets attached to the rotor to fall out from it's place. 

But anyway, you can try, before buying new wheel 

Edited by Ch.Eng.62
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7 hours ago, electricpen said:

I'm probably going to try to straighten it myself. If that doesn't work - time to decide between an ACM2 and Tesla! This is forcing me to ride my mten3 more anyway which has been a little neglected. The accident that caused the damage was avoidable too. I was going down a hill pretty fast and saw this giant raised crack in the road. I've been practicing hopping over bumps and cracks and tried to jump it rather than slow down. I didn't get enough elevation and clipped the top of it at high speed and went flying. Even so, I almost controlled the landing but ended up in a controlled faceplant (class 2 according to the other thread...). Thank god for the flexmeter wristguards. I fully used my hands to brace my fall trusting the wristguards to work. Wrists are completely uninjured despite bearing the brunt of the fall.

Also, I didn't notice the sound/feeling right away after that incident so it actually could have been from one of my jumps later. I hop off curbs all the time so maybe it warped the rim a little and then me hopping off curbs a few times bent it out further until it looked like the picture above (there is another smaller bend on the opposite side of the wheel right under the valve. In any case I'll try fixing it tomorrow, thanks for the advice!

Worst case you would need to buy a new motor. Probably ~$300. Certainly a lot cheaper than buying a whole new wheel. Then again, maybe you just want an excuse to buy a wheel ;)

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16 hours ago, electricpen said:

So I had an unfortunate visit with the pavement today and the crack I hit was big enough and I was going fast enough that I have bent the rim on the wheel. 

Where did this happen? So we SF riders can watch out.

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6 hours ago, who_the said:

Where did this happen? So we SF riders can watch out.

There are some really huge potholes on McAllister going down the hill. It was dark so I decided to stick to the sidewalk since I wasn't positive I had memorized where all the giant potholes were. It turned out there was a raised section of sidewalk pushed up by a tree root at least a few inches that I couldn't see very well due to all the leaves on the ground. I didn't realize it until the last moment and tried to jump it. I think I might have done better by trying to emergency stop which may have lead me to roll over it ungracefully but without damaging my rim.

I'm actually not positive if it was golden gate or mcallister with the sidewalk ambush though as I took both throughout the night (I was moving so I went back and forth a couple times).

 

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1 hour ago, electricpen said:

I'm actually not positive if it was golden gate or mcallister with the sidewalk ambush though as I took both throughout the night (I was moving so I went back and forth a couple times).

Wait... Are you saying that you moved house using your EUC? 

 @Smoother - This demands a certificate! 

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12 minutes ago, The Fat Unicyclist said:

Wait... Are you saying that you moved house using your EUC? 

 @Smoother - This demands a certificate! 

I realized I forgot to move a few items out of the fridge so I went back and grabbed the stuff from the freezer and rode back with it. I also went to return the key and forgot one of the keys so I had to go back to get the key and then back... so a lot of trips.

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  • 1 year later...

Were you able to fix your rim? Can anyone refer me to info on fixing a bent rim. I just got an identical bend in my own.

On 1/8/2018 at 9:13 AM, Jrkline "Wheel Whisperer" said:

This  is actually a pretty easy fix and can be done with the tire on the rim.You just need the right tools and to evacuate the air from the tube.I had a similiar situation happen to one of my wheels and fixed it no problem.Your best bet is to probably find a good bike shop like @Hunka Hunka Burning Love  suggests.DO NOT try heating the rim or you may destroy the motor.

 

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Several people (me included) managed to fix such a bend with a bench vice. Assuming the bend is outwards (so clamping it bends it back). If it's bent inward, you need to get creative (such as putting only the bent wall into the vice, not the entire rim). Just be very careful not to overbend it or you might get some small cracks (not bad by themselves, but obviously they don't make the rim more stable). And use a piece of cloth, otherwise the vice will scratch/imprint into the soft aluminium rim.

Here's two threads about this topic. The video posted down in the first one also has an different solution if I remember it correctly.

Edited by meepmeepmayer
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11 minutes ago, meepmeepmayer said:

Several people (me included) managed to fix such a bend with a bench vice. Assuming the bend is outwards (so clamping it bends it back). If it's bent inward, you need to get creative (such as putting only the bent wall into the vice, not the entire rim). Just be very careful not to overbend it or you might get some small cracks (not bad by themselves, but obviously they don't make the rim more stable). And use a piece of cloth, otherwise the vice will scratch/imprint into the soft aluminium rim.

Here's two threads about this topic. The video posted down in the first one also has an different solution if I remember it correctly.

Thanks meeper, so I just investigated it further. It is outward so that's good. But it's cracked in such a way that I can shine a light from the bottom of the rim and see the light slightly on the other side towards the screw D: !!!!!! I'm distraught. 

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There's no big mystery to it. It's a purely mechanical problem. If you can bend it back and riding with that rim works, you fixed it. Otherwise, you need a new rim (motor really). Light shining through or not (though I have to admit, light sounds bad). So... good luck:whistling:

Post some photos if you like. But all we can do is guess if you can bend it back successfully and if the repair would/will hold.

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On 1/7/2018 at 9:27 PM, electricpen said:

So I had an unfortunate visit with the pavement today and the crack I hit was big enough and I was going fast enough that I have bent the rim on the wheel. It has a rhythmic thumping feel now as I ride around although it is probably not audible to others. I can just feel it as I ride. Does anyone know:

1) How hard it is to fix this?

2) How dangerous it is to ride on it like this?

Maybe this just means I need to buy a new wheel???

bent rim.jpg

This is what it looks like more or less almost exactly

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  • 1 year later...
On 7/30/2019 at 7:35 AM, meepmeepmayer said:

Well then, no problem:) Carefully bend it back (slowly + no overbending) and it should be good as new. Mine wasn't as bad but I was surprised this simple repair worked 100%.

Was yours fixed with preheating?

I tried vises, did not bulge, was afraid of cracking  it. 

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9 minutes ago, jaiong said:

Was yours fixed with preheating?

I tried vises, did not bulge, was afraid of cracking  it. 

I did not preheat, but in hindsight that might have been a good idea, so if you can do that, do it.

When I repaired my rim, I didn't expect it to work and expected to need a motor replacement. So I wasn't very careful or concerned. I just put it in the vice and slowly tightened the vice until the wheel rim was mostly straight again.

I did get a little crack (of no consequence, but it happened), so your preheating idea is very good.

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c2zDQk7.jpgcar garage rejected me for fear of cracking aluminum rim, claiming they only handle steel /metal rims.

A little concern since I'm changing to higher tires (2.5" wide, 1.5cm higher than 2. 125"-KS16) Wonder what now? 

Edited by jaiong
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