wgscott

I've got an Ibis aluminum mtn bike wheel-set. It has asymmetric rims, and apparently it was built with aluminum nipples (not my choice). On the side of the front wheel that would require slightly longer spokes, I have now had two nipples fail. Oddly, it happens in the garage. My rear wheel is fine, as far as I can tell. The wheel-set has not been heavily used.

Should I have the wheel re-built with brass nipples, or brass nipples and new spokes, or cut my losses and get a new wheel?

Shimagnolo

Properly sized spokes put the head of the nipple in compression.
If spokes are too short, they can put the body of the nipple in tension, causing breakage.
Are the spokes long enough to reach the screw slot in the nipple?

See the first image on this page: https://www.wheelfanatyk.com/blog/rim-washers/

TiHabanero

Replace with brass nipples and forget about it.

shelbyfv

Yep, easy to do it yourself, one at a time.

wgscott

Nothing like tubeless to turn this into an ordeal of biblical proportions (so much so I would rather do it all at once and get it over with).

wgscott

No. I am nearly certain this is the cause. The question is what to do about it. (If brass is sufficiently more robust, perhaps just replacing the nipples will do it.)

Shimagnolo

If the spokes are too short, then you need to replace them with ones that are long enough.
Neither aluminum nor brass nipples can handle spoke tension if the spoke doesn't extend up into the head of the nipple.

wgscott

That's what I was afraid of.

MudPie

I didn't realize this. Thanks!

cpach

If the spokes are legitimately too short and are putting the nipples in tension this should be considered a warranty issue. Ibis is in town for you, maybe they'd be down with you dropping it off to be rebuilt.

Koyote

With this thread title, I was really hoping for a laugh or two with my morning coffee. You people are slipping.

dedhed

Right! I was ready to suggest Bag Balm.

wgscott

I tried.

79pmooney

Never tried it but I bet you could use Bag Balm on the threads to good effect. Also the rim ferrules. Wouldn't stop the cracking but would probably work very well for the build.

Shimagnolo

For Koyote:

rydabent

Well--------------------------that thread title cause coffee to run out of my nose, and splatter on my keyboard.

davidad

Replace the aluminum with brass. Even if they don't quite reach the head they will hold up. Anecdotally the first wheel I built had a few of the threads of the spokes showing. The wheel was laced to a 28 hole SA hub on a refinery beach cruiser. When I retired I gave it to Grumpy who used it until Muscle Head backed a pick truck over it. It lasted 10 years in that environment.

Mad Honk 

If the spoke nipples are a bit too short, find some longer nipples like a 16mm that will give more purchase. I have been buying them from 365 Cycles and they are not expensive. (when used with Bag B they should tighten up nicely!) Smiles, MH

cpach

This is one of the reasons that longer nipples exist, but I'm unsure of how much stronger they are--I think they mostly just hide some threads. Depending on the brand they may actually have only have as many threads cut as a 12mm, and thread strength isn't a major issue for nipple anyways--a handful of threads hold most of the force regardless. If the spoke is too short there's still going to be putting a portion of the spoke in tension. Ibis wheels, even their aluminum ones, are frickin' expensive and they should be RIGHT.

unterhausen

It would be a pain to go through all the work of nipple replacement and still have failures. Definitely sounds like the spokes are too short.

wgscott

Sorry I checked out. No power/internet for several days. I can't find the link, but Zinn asserts that spokes too short is nearly always the cause of this. I don't know for sure, but two failures in the comfort of my garage so far this year suggest something is going wrong. I have never even seen this kind of thing before (probably because all my other wheels have brass nipples).

Since Ibis is in town, I might try to get their advice. If they fix it for me, great, but even if not, it would be good to know if it is a known issue. (They have discontinued this particular wheelset).

wgscott

They seem to be closed to the public for the pandemic.

The rim retails for $99 and the hub (front) is an Ibis-branded no-name. There is nothing wrong with it, but this wheel might not be worth a re-build. It is for my steel off-road drop bar mountain touring bike, so maybe this is an excuse to get a new front wheel with a dynamo hub. What bugs me is I never really got to use this for anything significant.

unterhausen

Aluminum is a little weaker depending on the alloy. And I think it might be more susceptible to fatigue failures. But I doubt switching to brass is going to safe this wheel, the short spokes should be replaced.

In another thread, you previously mentioned that your shop didn't have the right size rim tape. You need to find someone that does. I'm not particularly happy about using tubeless tape, but all my wheels have it now even if I use tubes.

cpach

I'd try dropping them by Family Cycling Center or Spokesman. Too bad they won't deal with you directly but those are both pretty nice shops and should sort you out. Should be worth the time. Maybe get a dynamo wheel built in the mean time.

wgscott

I bought them at Family, so maybe that might be the way to go. Santa Cruz is taking the isolation pretty seriously (except for the morons on Westcliff giving out free hugs).

Thanks again for all the advice!