Sjtaylor

I have a wheelset with damaged rims. Both rims had dents at the brake pad surface which I removed with a broken hammer handle punch at my anvil. The rear wheel has a radial hop from a hit. It's not a sharp dent but more of a swale about 1/16" deep. I attempted to remove some of the swale with very little success. I've been riding these wheels for maybe at least 200 miles. I don't notice the hop except on smooth surfaces and especially on smooth fast decents.

I know little about wheels. I've always just used what came with the bike. Should I be content with how these wheels perform or are they of the quality where replacing the rims is a good option. I've always wanted to try my hand at lacing a wheel. Thanks.

Andrew R Stewart 

The photo doesn't provide much detail so we have to take your text as the situation. You say you don't notice any issues while riding... In many books this means no functional problem. Somehow I think this isn't the case or this thread wouldn't have been started.

Since Mavic is sort of "troubled" currently, finding OEM replacement rims for this wheel set might be a challenge. Their hubs are fairly well regarded, and if a new rim was available, most would say worth the rebuild.

I tend to consider the braking action of the rim to be high on my list of acceptance. Can you feel the dents when applying the brakes? Next up might be the evenness of spoke tensions and how that speaks to the long term "stability" of the wheel. Are the spokes all still fairly equally tensioned per side? Andy

Sjtaylor

After removing the dents in the braking surface the braking is very smooth and it’s very difficult to even find where the the dents once were. I put the wheel with hop in my trueing stand, checked spoke rightness and loosened and tightened a few spokes attempting to remove some of the hop. I don’t know if I improved it much if at all.

I think I’ll take the wheel by a LBS to get an opinion. I haven’t bought wheels before so maybe it’s time to do some research.

BTW I don’t know how to show wheel hop in a photo so I just photographed to identify the rim.

adipe

it can be very difficult to pull out a flat spot on the rim in order to end up with uniform spoke tension and low radial runout. it can be difficult to do that even if you have the best tools for the job. if you don't care too much about accuracy then straighening out a rim(wheel) is most easily done after loosening one or more spokes and then applying some hits, preferably through a soft wood on the rim. one easy and quick way to do it is holding a hammer's handle tight on the rim and then hitting that handle's end which would be some distance away from the rim, sideways. but all this supposes the wheel was accurately built before the accident. this technique is easy to do with 4 hands, 2 individuals. one person gripping the other part of hammer, where the handle enters the metal part.

i prefer to have a more gradual and precise procedure which involves what is called stress relieving after sorting out spoke tension (meaning i also measure radial runout on each spoke as to adjust spoke tension according to runout) and gradually increasing tension, with the stress relieving procedure at every stage of building up tension. the stress relieving procedure technique gets complicated when straigtening a bent rim is needed. i get to use my feet and hands simultaneously and pull the rim hard when the rim has not only a flat spot but also a slight taco (all this being evident at zero tension or just uniform tension).

i can go to extreme spoke tension values (and then backing off after accurately straighening the rim) but i only do it after applying the proper lubricant at the nipples-eyelets interface and also in the spoke threads. i also lower torsional stress on the spokes/eyelets while building tension by temporarily releasing a bit of tension while turning the nipples.

a wheel that is built up with uniform and high enough spoke tension is less likely to develop flat spots, by the way. and one more thing... spokes that don't have high enough tension can unscrew from the nipples as the tension is momentarily lowered to zero from large dynamic loads. having some locking compound in the nipple is not the best solution to prevent this because even if it can prevent spokes becoming loose over time the rim and spokes will fatigue and also the wheel (rim) will be more vulnerable to being deformed. flat spot, taco or a bit of both.

the wheel in the first post pic is low spoke count and did not have high enough spoke tension to begin with. possibly has some locking compound in the nipples too which can be hard to work with because of the additional torsional stress on the spokes and rim (at the spoke holes) due to friction.

it can be very hard to find a mechanic that understands all these things and also have the patience to fix such wheels. low spoke count is harder to repair. easier to build up but lower maximum load. main reason to have low spoke count is having just a bit less air drag. too low advantage for the non competitional use compared to the reliability issue.

Sjtaylor

Thanks for the detailed explanation and education. It’s just what I need.

How about this...

I’ll put the hoppy wheel in my trueing stand and locate and mark the deepest point of the swale and where the swale starts on both sides of the deepest point. I’ll loosen all the spokes and remove one or two spokes at the deepest point of the swale. I fabricate a radial support that hugs the rim but is relieved above the swale. With a C-clamp and wooden block Ill attempt to pull out the swale. I probably won’t get it perfect but if I can reduce the hop so it’s not so noticeable I’ll call it a win.

what do you think?

Andrew R Stewart 

This technique is an old method that has been forgotten by many and no longer cost effective in the LBS world. One tool I always wanted to make was the turnbuckle that had one end against the hub shell center and the other against the rim. But as I alluded to before, this was back when standards of cost and expectation of delivered product were different then current times. For home attempts all standards are off the table. For professional jobs the window is vastly narrower. Andy