Bent rim walls ok to ride?

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81style   10 mW

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Bent rim walls ok to ride?

Post by 81style » Dec 27 2018 7:22pm

Today while mounting some new tires I managed to bend my rim walls. Because the rims are still perfectly circular and true, is this simply an aesthetic mishap, or are there safety/performance impacts that I should consider before riding? These rims are on a 3kw EEB.

Sanity check please. Thanks.



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amberwolf   100 GW

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Re: Bent rim walls ok to ride?

Post by amberwolf » Dec 27 2018 10:16pm

If it's steel, you can bend it back.

If it's aluminum, don't; it'll fracture and break, with the stress crack splitting the rim circumferentially along the bend line over time (faster the bigger teh crack gets) an tire pressure pushes on the bead seat.

I rode a bent aluminum rim on the heavy CrazyBike2's rear wheel for quite awhile, months at least, probably longer, before the crack created by bending it back split it far enough that I had to change the rim.

I'm still riding the same model aluminum rim with a bent section I left alone (after a serious pothole) on the much heavier SB Cruiser trike, and have had no problems with it yet.

Both of mine were bent inward, not outward like yours, but I'd guess yours would be the same as long as it's good tough rim. Since you said it happened while mounting the tires, then unless there was serious abuse doing that, I'd guess they're not that good. If I had rims that bent up like that while mounting tires, I'd replace them with better ones (and get my money back if I could).

Mine were bent by deep sharp-edged potholes at speeds near 20MPH, with a 400lb+ bike+rider combo for CB2, and 500lb+ bike+rider combo for SBC. So...quite a lot of force.

You can search my build threads in my signature for the pics and details if you want to compare.

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trazor   100 W

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Re: Bent rim walls ok to ride?

Post by trazor » Dec 27 2018 11:43pm

My rims are completely bent because rough riding. In fact I created a tool to bend them back, even if they are aluminum. BUT... I ride mostly offroad (check my signature). If doing highway speeds between cars is your choice... I think you should not bet your life to a maybe low probability mechanical failure. It depends on the purpose of your bike.

Here is the tool, based on 12mm plate. It is used with about one meter cheater bar.
IMG_20181228_013648.jpg (107.42 KiB) Viewed 161 times
I agree with amberwolf... you are doing something very wrong or the rim is cheese if you bent it mounting a tire. Are you using soapy water to mount the tire?

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