777funk

I hit a curb once head on (lost control on a curve) on an old Puch road bike and tried to bring the wheel back to true after putting a 1/4" of warp into it. I could not retrue it. I have a new addition of another Puch (Sears branded) and the rear wheel has a slight Egg shape to it. As I ride, I can feel my seat going up and down. I tried last night to pull in the hump and it's better but still not perfect.

Are some wheels just not going to true? I've watched plenty of videos on the topic. I think I understand the concept. I still tend to think I have more learning to do. I ask though because I brought that original Puch wheel to a shop to true it and they gave it back to me and said they couldn't fix it. That was my only recent bike shop experience. Maybe that tech didn't have the skills required???

100bikes

Some wheels just cannot be trued.

Wheel truing is working in three dimensions- true/straight, round and dish. A rim bent beyond the limits of
"mostly straight" will never true up correctly.

The easiest way to assess the situation as to whether a wheel/rim is true-able is to release the tension by loosening the
spokes of the entire wheel. Done evenly, round an around the wheel to the point where the spokes don't rattle, but there
is little tension, and spinning the wheel.

A "tacoed" rim will be easy to spot.

In general, spoke tension can be increased/decreased to facilitate true, but each turn of a spoke nippel affects all three.

The issue is that a bent rim acts as a spring. Once a rim is sprung/pretzeled/twisted/tacoed, it will try to return to that state.

Methods are varied. Basically, its a process, and a little turn of a group of spokes does more to correct the imperfection
than turning one spoke a lot

A final seating of the spokes after truing a wheel can "release" the spring. I do this by laying my forearms across the wheel,
with my hands at 10 and 2 o'clock and flexing the wheel a bit.

Doing this, you will hear the spoke ping(set). I turn the wheel 90 degrees and repeat all around the wheel and then check
the wheel for true , round and dish once again.

A wheel that does not hold basic true after this act, likely never be ridable to any degree..

When the spoke tension in one section of the wheel is to much different than another, you have a very unstable situation.
The slighted bump and wham- the pretzeled rim returns.

Hope this helps a bit. It takes a while to be good at wheels, but well worth the time involved.
rusty

FBOATSB

Right. You can't use spokes to re-bend a bent rim. I'd completely disassemble the wheel and check the rim dimensions/trueness on a flat surface. If you can't physically bend it back to some minimum sort of roundness it's time to cut it up and make something else out of it. Videos abound on this.

777funk

I am working on a wheel with almost 0.100 of oblong out of roundness. The worst spot is approaching the dial indicator but the spoke is almost loose to no pitch while I've tightened the other side. The entire rim is has out of roundness probably +-0.030" or so.

You guys that can true wheels deserve big respect!

100bikes

The closer you get to "perfection", the more each small turn of a spoke(in either direction) affects the finished wheel.
rusty

FBOATSB

You mentioned old Puch road bikes. You need to ask a mod to move this thread to C&V so many pics can be demanded. Are your rims steel or aluminum? A lot of old rims that I seem to find seem to have a flat spot built in where the rim is welded or pinned, but I mostly gravitate towards old junk and am OK with that. Wider tires and lower pressures makes these things less distracting in my opinion.

777funk

iI cant seem to get it any better (maybe a little worse). Time to ask for help from a bike shop.

Retro Grouch 

My trick is to loosen every single nipple until just 1 thread is showing. Then I gradually bring the wheel into tension by tightening every nipple by the same number of turns - maybe 2 turns at the start, then just 1 turn and, as the wheel nears tension just 1/2 turn. If the rim hasn't been tweaked too badly, and none of the spokes or nipples have been previously replaced, that will usually get the wheel pretty close.

Iride01 

I use to true my own wheels, but I did it with just a spoke wrench and loosening or tightening spokes till I had a true wheel.

However eventually I realized that some spokes on my very true wheels were now very loose and some spokes very tight. So not being one to want to buy tension meters and other tools of the craft, I just started letting the wheel guy at the LBS do them.

It's never cost me very much money. Probably less than all the tools I'd truly need to do a decent job. And my wheels actually stay true without any fussing that I use to do.

777funk

I think my main problem is unrealistic goals. This is an old chromed rim with a seam (70s Sears Puch 10 speed) and I was hoping for say 0.010 to 0.020" runout in any direction. Looks like Park tool calls 0.5mm (0.020") lateral and 1mm (0.040") radial good.

This rim has a welded seam and probably a few road dings. There's no way I'll get it as good as Park calls for. It's probably 2x or 3x that tolerance (1/8" i.e. 0.125 radial). I'm guessing I should just ride the bike and deal with a little wobble. I did see a guy (Oz cycle) on youtube remove a few spokes and use a tool to push out dents using the hub as a fulcrum. I'll bet a squeeze clamp could do this for me.

I will try again. Thanks for the feedback! If nothing works as good as I hope, I'll either just deal with it or bring it to a bike shop if it's affordable.

philbob57

Steel rims need a lot of space for stopping when wet. You might do better by buying a C &V wheelset with aluminum rims via Craigslist or facebook marketplace.

Bill Kapaun

IF the metal has "stretched" from an impact, you'll never get it "correct".
You may get it kind of straight....until the next impact when the spoke tension normalizes.

I had a rear rim on a used bike I purchased that had such uneven spoke tension, it got a brake pad rubbing wobble from simply doing a wheel stand on the front and having the rear just drop to the ground a couple feet as I was stepping off to the side. (I wasn't used to the grabby front brake and had to make a quick stop)
The wheel trued/tensioned up near perfect!

cxwrench

Why can't he just post the pics here? It's a mechanical issue, not particularly a C&V issue...unless you're just trying to be funny.

777funk

Thanks to all for the comments and encouragment. I bought a park tool 3 in 1 and tried on another bike (Fuji with aluminum rims) and it turned out Great! I think it had to do with this rim being an easy candidate because everything worked like it shows in the books/videos.

urbanknight

I have built and trued hundreds of wheels. Truing a new wheel you just built with a new rim is one thing. Fixing a damaged rim is a whole other thing, and that can't really be done by adjusting spoke tension. If I'm truing a used wheel, I carefully check the spoke tension along the way. The moment it goes outside the acceptable range, I tell the customer it can't be fixed safely.

SJX426 

I like to try to save a vintage rim if it isn't too far out. Placing just the rim on a marble or glass top helps to identify the lateral "flatness" of the rim. I mark where the deviation starts and the location of the highest spot. A piece of wood is placed under the first two marks and the force is applied to the the third. More often than not it is centered between the two deviation marks. Iterative checks and bending is done to until flatness is achieved.

the same sort of approach is done for "flat" spots in the radial direction. Of course this is determined when the wheel is assembled with the spokes lightly tensioned so the rim doesn't shift as it rotates and the rest of the rim is radially consistent. I have seen tools to address this damage but I don't have one.
I did this instead with the spokes completely loose.
P1030738 by superissimo_83, on Flickr

Again, this is an iterative process of bending and checking. In this case the outside marks may move.
I used a rasp to create the curve to match the inside of the rim.