tomtomtom123

I asked a shop to build a new wheel for me. They did it really fast and shipped it to me in 2 days, as I'm going on a long tour on Monday and I noticed that the rear brake walls were worn and I didn't have time to swap the rim.

But the tips of the trailing spokes on the non-drive side, with spoke heads on the inside of the hub flange, seem to end at the bottom of the brass nipple head or possibly only 1/2 a thread further.
It's shorter than where I would like, but is it too short?
What should I do?

I know that the problem with the short spokes is that the nipple shaft will be fully in tension, instead of a longer spoke going past the bottom of the head compressing a part of the head.
But is this still safe for brass nipples with 32 spokes?
It's a 406 rim so the stress from bumps will be greater as the spokes are shorter, especially with a loaded rear rack.

The drive side spokes are almost all flush with the bottom of the nipple slot. One is 2 threads lower.
While the non-drive side leading spokes with spoke heads on the outside of the hub flange are around 1 thread lower than the bottom of the slot.



The shop's website requires entering spoke lengths to order, so I calculated based on the old rim dimensions of the same model that I had purchased from them before.
But I measured the new rim on the wheel they sent me to be shallower profile by around 1.3mm, so the new rim ERD is probably 2.6mm wider than the old rim.
I assumed as they were building the wheel, that they would choose the spokes accordingly, and I noted in the order to please choose the correct length as my values were based on the old rim, but their worksheet shows the same spoke lengths that I submitted.

The 1.3mm shallower profile is similar to the difference in most of the spoke lengths between the new and old wheels, but doesn't completely explain why the trailing spoke ends on the non drive side are even shorter by another 1.5-2mm.
Maybe it's the outside elbows not being pressed down towards the flange during the wheel building?

What to do now?

tomtomtom123

I was thinking that possibly the new hub has thicker flanges compared to the old, causing a greater discrepancy in length between the leading and trailing spokes on the non drive side. But I can't measure it.
The overall outside of flange to flange width is the same though, and so is the flange-center offset or at least within 0.5mm.
And then maybe the 1 thread difference between the non drive side and drive side spokes could be the nipple holes in the rim not being exactly centered with the rim walls.

Andrew R Stewart 

Seems to me like either a slight miss measurement was entered into the calculator or the shop didn't have the "perfect" (make your own definition) length and knowing of your quick need did the best they could. Either way I doubt the slightly short NDS spokes will become a problem. Andy

mpetry912 

so let me get this straight, the shop "builds" the wheel for you but they require YOU to specify the spoke length ?

leads me to question what kind of service they are providing

Andrew is probably right, go on your ride, you should probably be OK, but I would not send that "shop" any more business.

/markp

maddog34

Just ride it and quit Obsessing over a couple threads.

ps.. if you were truly concerned with the strength of your rear wheel, you'd have been riding a 36 or 40 spoke rear wheel, and not riding one with worn out brake tracks in the first place,then deciding to half-correct your errors a few days before a tour.

tomtomtom123

The website doesn't have an option to select no length. Maybe it's an oversight on the web design. I thought the service description meant they would measure and select the right parts, but it might be a translation error. It might have just meant they they provide a worksheet for deviation and tension measurement. However I would have thought they'd calculate themselves since they are providing all the parts. I added a note asking them to select the correct length but maybe the translation want l wasn't clear.

tomtomtom123

The problem is not a couple of threads. It's that the threads don't engage the nipple head.

The tour coincides with giving up the apartment and everything inside it, and quitting work so I didn't really think about the rim wear until I checked it again after packing the bike.

sweeks

How does a shop build a "new" wheel using a rim with worn-out brake surfaces?
Inquiring minds want to know...

mpetry912 

so is this a non US shop ?

"translation" from where ? Seems like measurements should be obvious in most modern languages

/markp

tomtomtom123

They build trikes and other things, and provide wheels to other local bike companies, so they specialize in small wheels and have a large stock of spokes.

It won't be a problem even if there's no thread engagement inside the nipple head on the NDS? The nipple will be all tension. Although without the torque from the pedals. But bumpy roads and loaded rack.

maddog34

ok.. here's my advice:Get off the Internet and build your own wheel.

tomtomtom123

I built the old wheel. I didn't have time to swap the rim, and I already sold my truing stand along with most of the other personal items in the apartment before I realize that the rim wear was quite significant.

The old wheel was 36 spokes, and they still had stock of that rim but I didn't know the turnaround time would be so fast otherwise I might have asked them to swap it for me. They only had similar 32 spoke hubs so I ordered the 32 wheel

mpetry912 

this illustration that I got somewhere may be helpful

/markp

tomtomtom123

Assuming I use the wheel as it is, if a few spokes/nipples broke, can I replace the spokes with longer ones or only with the same length? They're double butted 2/1.8/2. The difference of 2mm length in the thinner section would be around 1.5% of the length of thin segment. It's not much but would the longer replacement spoke stretching further under load cause problems with the adjacent spokes?

Andrew R Stewart 

I think you are overthinking this stuff.

BTW don't assume each spoke length is made independent of other lengths. It's quite common for one butted spoke blank serve a number of final lengths, with only the thick butt length that has the threads on it being different.

Can a nipple without a completely engaged spoke in it crack and break off at the head? Sure. But this is more often with alloy nipples and after a lot of miles on low count spoke wheels. There have been millions of wheels with spokes that are a mm or 3 short that never have a nipple issue.

As far as replacement spokes affecting adjacent ones- The real life issue is more about the new spoke going through its bedding in and thus the repaired wheel "goes out of true" just after the repair. Not that the nearby spokes care about their new neighbors. Andy

cpach

It's weird they have you specify the spoke lengths. I would have rebuilt that wheel with longer spokes if I built it for a customer (after some harsh words and a snack). While it's likely to be fine, it is a legitimate durability concern if the spoke doesn't thread past the edge of the rim bed.

There are no problems if the butted section is a different length, or indeed a completely different butting profile, so I wouldn't worry about that.

Piervinc

Echoing this. I’ve only seen alloy nipples break from this sort of thing.

tomtomtom123

I called the shop and they said it was safe and that it won't break, although they admit that it is short.
They said they did calculate the spoke lengths themselves but didn't explain why they're all a little bit short.
I assume that they must have used the old ERD that doesn't match the shallower profile of the new batch. Or they simply used my calculations.

But they explained that for the NDS spokes with the elbow going out of the flange causes the linear distance to be longer resulting in the shorter thread engagement compared to the spokes coming from the inside of the flange. 2mm is a significant difference though.
Although on the old wheel that I built myself with a similar hub with same dimensions and the same model of rim (but with 36 spokes instead of 32), both the inside and outside spokes have the same thread engagement, but I did a lot of stress relieving with the rubberized handle of a hammer and pressed the elbow to get it flat and flush against the hub flange. I wonder if they didn't stress relieve at the crossing of the spokes in contact.

I would use the new wheel as it is, as I can only take one of them with me on the long tour (the old or new one), but I will still occasionally feel a bit uncomfortable wondering about the non-optimal spoke lengths ending at the bottom of the nipple heads..


I recommended to them to add an option to specify no length when adding the spokes to the cart on the website when someone orders wheelbuilding service.

FBinNY 

Hard to say either way about this wheel. Yes, spokes not engaging the nipple's head are less than ideal, but a brass nipple is not that much weaker than a 2mm spoke. If the wheel were built with DB spokes, I wouldn't worry at all.

OTOH the real issue isn't the build, but the builder. A length difference between leading and trailing spokes is 100% avoidable and I consider it evidence of an inept builder.

There two possibilities.

It's either a case of the hub being twisted with respect to the rim. Something that doesn't happen if the builder starts out with all spokes pulled up to the same length, something that all decent builders do.

The second possibility is much more serious. This pattern may indicate that the spokes from thd right an left flanges aren't phased properly. This happens during the lacing, usually to amateur builders who fail to route spokes correctly when lacing the second flange.

Either way, this is a vote of no confidence in the builder, and I wouldn't take his wheels far from home.

Kai Winters

If you requested the fast turn around in order to have the wheel ready for your ride it is likely the shop didn't have the correct spoke length in house and used the closest, still useable, that they did have in order to meet your needs.
Likely it will survive the ride.
Considering you used a worn rim you really should have just bought a new wheel...unless none were available to meet your time needs then everyone just did what they could.
The shop should have notified you they were going to use a shorter spoke than what they should have to get your okay so you'd at least be aware.
From your description they didn't 'build a new wheel', they relaced a worn rim with new spokes. Why did the wheel need a full relacing in the first place?
Why was this a last minute need?

Don't blame the shop for doing the best they could with what they had on hand. If I place an order with QBP it arrives in two days, unless I pay a large amount of money for overnight shipping. I have over 100 different spoke types in our shop and still get in a wheel that has a spoke type/length/color/etc that I don't have and there are times when we do what we have to do...like buy a spoke thread cutting tool, sigh...to complete a repair. I may have to ask the customer if I can use a different color...standard silver on their black spoked wheel, etc...or round because I can't find their specific bladed spoke or I just need one spoke and can only buy a box of 100 knowing I'll likely never need another of that spoke again...

Last minute repairs suck...blaming the shop is just wrong...

Lombard

^^^This!!!^^^

You may get away with this on the left, but then you may not. Personally, I would rebuild the wheel.

FBinNY 

Yes, and no.

I agree that last minute repairs suck, and that's entirely on the OP who must have known his plans and should been smarter.

However, that doesn't excuse the shop, who could have said they couldn't do the job within the deadline, unless ......

In any case, the probably wouldn't have been as bad if it weren't for the high/low problem which is 100% on the builder.

IMO the problem isn't as much about short spokes as it is about poor quality, and last minute doesn't excuse that.

ThermionicScott 

If the spokes are too short by enough, one could possibly relace the NDS side with one fewer cross (using washers to consume some of the excess if necessary.) But that's upsetting a working part that may not end up giving you any issues, so I'd just leave it alone. Sounds like you may have enough other stuff to worry about. Good luck with everything.

FBinNY 

What's done is done, so put it out of your mind and enjoy the trip.

It SHOULD hold up, and you can deal with it later. If it doesn't hold up, you'll deal with that if and when, since your only alternative now is to delay or cancel the trip.

FWIW and for the future, never do major work less than 1 week before a long tour or important race. Also never do any work less than 24hours before the same.

WizardOfBoz

Generally, if Andy makes an observation, I trust it.

From StackExchange:
"A typical spoke has around 8-10 mm of threading on it, and you don't necessarily have to engage all of it with the nipple. So it's not super sensitive to small variations in length."

On the other hand, Lennard Zinn (former US National Cycling Team member, owner of Zinn Bicycles) points out that if the spoke doesn't extend past the start of the nipple head (see diagram several posts earlier) that you could have spoke head breakage. Expecially if there is no grommet for the spoke head to seat in, and if the nipples are aluminum. I'd get some spare nipples and ride it. If you break nipples you may want to get longer spokes. If not, enjoy the ride.