"I would never rebuild a wheel, even a new one." - mechanic to me
 

I just bought a Surly Disc Trucker. It's fitted with Alex Adventurer, 36h black rims (which I can't find on the Alex website). I have decided to fit a generator hub to the bike, and figured I would leverage the shops 30-day discount for accessories and labor. The rim looks to cost around $30 (assuming the shop can find one with a black side wall). I can't seem to wrap my head around the need to buy a new rim for my build. The mechanic explained that it is just too risky, even with the new rim on my bike -- it will likely be very difficult to true. "Just keep the current wheel as a spare, or give it to a friend."

Does this sound rational to everyone here? I have no experience with this!

There would be no problem lacing the rim to a new hub. However, if a new hoop is only $30, I think keeping the wheel as a backup makes sense.

A spare wheelset is always good to have. I don't currently have one since I used my good set on my new bike build and put the spare set on my old bike which I sold... Guess I need to go buy a new wheelset!

He may be incompetent. Find a new shop to build the wheel. I've rebuilt many wheels with no issue, from replacing spokes to hubs to rims, re-using parts that were 20 years old. If he's afraid of re-using a new rim, he might be scared stiff of liability because he's not sure of his wheelbuilding ability.

On the other hand, are you absolutely *sure* you want to use an Alex rim on your new wheel? Maybe that's the hesitancy the mechanic has...

I would never disassemble a decent wheel. Not because rebuilding on a slightly used rim would be a problem, but because the built wheel is worth more that what you'd save.

Also consider the shop's issues. If they disassemble the wheel, it's a time consuming process to do so without risking distorting the rim. If you do it, they are relying on you to do it right (though they can tell you how), then is the question of sorting the spokes for reuse (sort 4 piles by flange and direction), and then the nipples may be in less than perfect condition, but that's a small cost.

Save the wheel and build fresh.

If you were building it yourself, then you could decide what is best for you. I'm not sure how "risky" it is, but the shop still has a choice in the matter. Find another shop, or lace it up yourself. You will still need to get the correct spokes.

You could sell it for more than your cost of a new rim.....................

there's a difference between the mech voicing an opinion about wheel building in general, and turning away business. it sounds like the former. in addition, the statement may also be a result of differing opinions as regards the 30-day discount for accessories and labor.

I'm wondering why he needs a new hub in the first place. I'm not at all familiar with the replacement hub. Is it of better quality?

Personally, I hate tearing down an old rim, and I could see a shop turning down that kind of business if they are already offering a discount.

He wants a new hub that comes with a generator built in to it, AIFAICT...

switch to generator hub

The labor cost alone to unlace the old wheel, transfer in a new hub and relace it, even assuming the hub dimensions are close enough together to be a direct replacement, are probably a large fraction of the cost of a complete new wheel. Add in the cost of the generator hub itself and I agree that buying the wheel you want and either selling or keeping the old one intact as a spare is the smart way to go.

All true.

But the logic the mechanic used pretty much translates to, "I suck at wheelbuilding."

He can't build a wheel with a used rim? If you can't build a wheel with a used rim, you really can't build it with a new rim either.

+1
A generator hub is going to require new spokes.
So, you have a labor intensive job building a new wheel with a entry level rim.
Add that this is the "busy time" for bike shops and I can see the reluctance of the mechanic in building a so so wheel.
My LBS has a 2-3 week waiting list for repairs during this time of the year. I'd think if you approached the mechanic in January you'd get a similar response, but more willingness to do it if you were willing to PAY.

I don't think he's saying I can't, he's saying I won't.

I build wheels on a referral basis (not my living) and turn down jobs that I can do, all the time. It might be because the client wants me to use parts I can't vouch for, or do something I don't think will hold up. The finished product reflects on me, and if it doesn't pan out for any reason, nobody will factor that I was given poor raw materials or direction.

In the case of a used rim, what if the prior build overstressed the rim forming unseen latent stress cracks? Who's fault would it be if the rim showed spoke hole stress cracking 30 days out?

Commercially, it makes sense. Disassembly takes time, and if the rim - despite being new - has taken a ding, rebuild will be longer and might not be entirely satisfactory.
Using new stuff is just faster and more predictable.

But mechanically, it should be a non-issue.

Would you expand on that, please?

If you disassemble a tight wheel by removing one spoke at a time, you can either warp the rim beyond it's elastic limit, or increase the stress on near spoke holes high enough to cause stress cracks.

This is probably less of an issue on modern overbuilt rims, but it used to be possible to rip out an eyelet on light rims simply by cutting out nearby spokes.

When planning on saving a rim, I reduce tension by degrees, starting with the already looser (applies to rear or disc wheels only) side, then when these approach zero tension, do the right by degrees until tension is low. Then spokes can be removed one at a time without issues.

This is a time consuming process, and takes about 1/3rd of the time a new build takes, so would have to factor in the total labor cost.

Thank you!

Yeah, but this is a pretty new rim on a bike the OP just bought.

All the other reasons make sense - the labor to take the wheel apart is probably more than the rim is worth, and that's pretty much sufficient right there.

But risky? Difficult to true? Those are bull, and IMO indicative of someone who doesn't know his craft very well.

Look how easily you come up with legit reasons it doesn't make sense.

Since new spokes would be needed, and OP may have no use for the old, they could just be cut out without significant labor. Admittedly cutting the first few spokes cans stress the rim until the overall assembly loosens up, but folks do this all the time without rim damage. I've personally done it many times without any harm to the rim that was detectable during the rebuild.

On the other hand, I agree that keeping the spare wheel intact, perhaps as a trainer wheel or just a spare has a lot of merit.

Another thought about dissambly stressing the rim, especcially the traumatic disassembly method of cutting the spokes: I have never heard anyone suggest that a wheel on which a spoke snapped while riding should not be repaired and continue to be used. Nothing could be more similar to cutting the first spke during disassembly than that.

Not worth it maybe, but not "risky" IMO.

Wow! I appreciate all the insights. I will just keep the old rim in my (tiny) garage. Having the spare makes sense! - JP