Truing Magnesium Wheels

[SpikeFC]

Anybody ever done that? Any ideas? I'm building a bike for a friend an I got a set of sweet original Magnesium wheels made by Sachs, and the rear one badly needs truing.

 

[Duchess]

I was always told there isn't much you can do, but I'm always skeptical of that claim (gives side eye to disassembled Shimano integrated shifters that truly cannot be put back together). Assuming it's truly magnesium, you might be able to heat it up to around 200 degrees to make it more receptive to adjustment, but that's about all I've got. If you get this figured out, I'd love to hear how you did it.

 

[SpikeFC]

I was always told there isn't much you can do, but I'm always skeptical of that claim (gives side eye to disassembled Shimano integrated shifters that truly cannot be put back together). Assuming it's truly magnesium, you might be able to heat it up to around 200 degrees to make it more receptive to adjustment, but that's about all I've got. If you get this figured out, I'd love to hear how you did it.

I'll keep you posted. A friend of mine will be trying to help me with this topic.

 

[pebblewurm]

In theory, the rims should be pretty bulletproof. Could any wobble be coming from the axle and bearings? Just an idea.

 

[SpikeFC]

In theory, the rims should be pretty bulletproof. Could any wobble be coming from the axle and bearings? Just an idea.

Nope, first thing I do in any wheels is a proper grease change and troubleshooting if any parts needs to be changed. The wheels that I'm talkin about are a product of Sachs.

Both in size 590 (older 26", bigger then modern 27.5"). Front one has a built in drum brake, and the rear one has a 3-speed coaster brake Dreigang hub. Both are cleaned, grease&oil changed, the front one needed only one of the cones to be changed. While the front one is a little wobbly to the left, the rear one is so wobbly it's impossible to mount any fenders, and it's even hard to put it in a position in the frame that the wheel would not hit the frame.

I'm still waiting for my wheel-truing guru, and his father to tell me if they succeeded in finding a method for truing them.

 

[Psychographic]

I hope you find a way to true them, they are beautiful wheels.

 

[us56456712]

Nope, first thing I do in any wheels is a proper grease change and troubleshooting if any parts needs to be changed. The wheels that I'm talkin about are a product of Sachs.

Both in size 590 (older 26", bigger then modern 27.5"). Front one has a built in drum brake, and the rear one has a 3-speed coaster brake Dreigang hub. Both are cleaned, grease&oil changed, the front one needed only one of the cones to be changed. While the front one is a little wobbly to the left, the rear one is so wobbly it's impossible to mount any fenders, and it's even hard to put it in a position in the frame that the wheel would not hit the frame.

I'm still waiting for my wheel-truing guru, and his father to tell me if they succeeded in finding a method for truing them.

I don't have experience with mag wheels but I have straightened badly warped wood rims by zip tying them to a true wheel and then tossing them in the snow for 2 days, then inside for a week. Then I took the rims off and flipped them and did the same again. They got true enough so that spoke truing did the rest, but it took many days as the wood would wake up overnight and change it's mind. I had to loosen all the spokes twice to try and get the rims to relax and start over again. Mag wheels probably don't have a memory like steel, they probably have the same properties as aluminum. Perhaps you could clamp them to a car tire rim and expand the low spots by gently heating them with a torch, then reversing and doing the same. Gentle pounding on the high spots with a plastic covered deadbolt hammer against a piece of old hardwood flooring might coax them back. This might result in changing them from potato chips into eggs. Clamping them to a welding table could also work but the tire rims might help you eyeball the roundness to make sure they don't turn into eggs. You would have to build something so the hub would clear the table, sounds like a harder solution then using an old car rim. I don't have a wheel guru so this is what I would do. Magnesium alloy sounds brittle, but they did bend without breaking so perhaps they can be coaxed back without breaking the spokes. I have successfully straightened vintage steel 3 piece racing hubs but could never take all of a bend out of a bent alloy hub. The alloy hub got better, less wobble but was still more wobble in the cassette than 1/2 the width of the chain so I figured it would not shift right so why build a wheel just to see. Last year I built a jig to try and straighten a late 1930s French road racing hub but I was never able to completely eliminate the cassette wobble so I had to modify a new one so that it was 114 mm OLD. So much fun.

 

[SpikeFC]

Actually I'll be picking the bike after christmas. As I suspected, my friend & his father did it!. The method was simple - I used a truing stand to precisely mark in witch way to bend the wheel. They just put the each of the wheel in a vice, and trued it by using a piece of 1m/40in pipe to bend the whole wheel. I'll post some films from before & after.

 

[Psychographic]

Great news!

 

[RustyGold]

Caveman style

 

[Duchess]

Good news as I've seen used ones cheap because they need to be trued and I've always liked the looks of them.

 

[SpikeFC]

So this is how the wheel looked before truing with the vice & pipe:


And this is after:


You have to be super delicate while bending the wheel to avoid any cracks on the spokes

 

[MattiThundrrr]

Awesome sauce!

 

[JaxRhapsody]

Good thing you didn't use heat and risk blowing them up.