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Old 08-26-12, 01:49 PM   #1
mrfunnyhaha
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Any hope for my rim? (radial hop)

Hey guys,

So I have a bike with a 2mmx28 spoke radially laced front tire that I had been using for utility hauling and commuting. I was putting a lot of abuse on it so I wasn't too surprised when one day I noticed a couple of the spokes had come loose and the wheel was out of true.

So, I popped it on my stand and had a go at it. The wheel has almost 2mm low hop at the spot with the loose spokes and I can't seem to do anything about it. Laterally, I can get it pretty true, but those spokes are still below average tension + the hop.

Park tool tells me

Quote:
If the rim shows an inward movement in one section toward the hub and the spokes in that area are already loose, the rim has been bent. This type of damage is not repairable.
Any tricks to try and fix this?

If this wheel is toast, any suggestions on what to look for in replacement super tough utility wheels?
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Old 08-26-12, 02:16 PM   #2
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Truing hops in radially spoked wheels is very easy, but the relative tension differences needed depend on the radial stiffness of the rim. The fact that the problem first manifested as some loose spokes at the low area indicates that the rim is bent inward there. As long as it's slight enough that it's still arched, tightening all the spokes elsewhere while leaving the low-zone spokes relatively slack will have the rim trying to shrink and bulge out there (like squeezing a balloon). This works best with radial spoking because there's nothing to resist the circumferential movement of the rim. When you've bulged the low area out to a high spot you then bring it back to line and align as usual, setting the overall tension within the target range, except for the affected area which will have lower tension.

This method works well with shallow rims that aren't too stiff radially, but stiffer rims need a bit of extra persuasion. My favorite method is to loosen the whole wheel slightly, and totally slacken or remove the spokes in the low zone. I then step on the low spot and pull the wheel up against my foot, pushing the area out to a slight bulge. Then retighten the low spot spokes until the now high spot comes into line, and align and retension as I would a nw wheel.

Don't forget that after all this work, there'll be stresses and twists in the spokes, so you have to resettle everything as if it were a new wheel.

BTW- if you can't save it and decide to rebuild, you don't need a super strong rim, just stop fooling around as aggressively.
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Old 08-26-12, 02:26 PM   #3
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Sweet, I'll give that a shot.

Thanks FB
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Old 08-26-12, 05:29 PM   #4
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A low hop just where the spokes are loose is not a good sign, actually if the spokes are lose the hop is not low but high or up, whatever the lingo used is...

IMO probably the rims have a dent, if thats the case if too bad you can hammer the rim a tiny bit. If are like 2 mms I wouldn't worry about it too much. Hope you know what are u doing, Is not hard but the situation can get worse... good luck learning
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Old 08-26-12, 05:37 PM   #5
Bill Kapaun
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IS it at the joint, opposite of the valve hole?
Many rims come with a flat spot there.
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Old 08-27-12, 08:11 AM   #6
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Quote:
Originally Posted by mrfunnyhaha View Post
If this wheel is toast, any suggestions on what to look for in replacement super tough utility wheels?
Given the type of riding you describe, "Not radially laced" would be a good start.
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Old 08-27-12, 04:48 PM   #7
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Given the type of riding you describe, "Not radially laced" would be a good start.
36 or 32 spokes would also be a good idea.
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