StevePGN10

I am replacing some broken spokes in a 27" rear wheel and have a problem for which I can't find information in the archive.

I loosened all the spokes, replaced the two spokes which had broken, used a ground-down phillips screwdriver to tighten the nipples until they cammed out, starting applying tension, got the wheel nicely true, then started increasing tension with 1/4 turns on all spokes. I was a happy wheel technician until I noticed that many of the spokes were poking out the inside of the nipple. I don't have access to a spoke tensiometer, but the spokes didn't appear to be unreasonably tensioned. I decided to loosen all the spokes and re-true. The wheel is true again, but I'm concerned the spokes are too loose. What can be done to determine sufficient tension when one does not have a tensiometer?

Would it be a foolish thing to re-tension all the spokes and somehow trim the exposed spokes? Something tells me that the manufacturer got the wheel properly tensioned with the spokes at their present length, and that I should be able to as well.

mrrabbit 

Spokes are too long....

If this is a single-wall 27" wheel, the spokes should top out at or slightly above the screwdriver flats of the nipples when proper tension has been achieved.

It was common way way back when distributors were using "American" spoke lengths to go with something close enough...provide to shops...and it wasn't uncommon to discover that when some of these wheels were finished off - the spokes were too long. However, they had threading for 16mm nipples - meaning grinding away the excess was no big deal.

Nowadays...grinding away simply represents hiding the problem...and the required fix.

For tension without tensionmeter, look up Jobst Brandt at Google Group rec.bicycles.tech

=8-)

FBinNY 

While I agree with mrrabbit that the spokes are too long, I'm not convinced it's an issue. To be sure, thread an extra spoke and nipple of the same type as you're using until the nipple can go no farther, Usually that has the spoke sticking out by about 2mm or so. That's your upper limit, and you really don't want to get there because then there's no more ability to true or tension the wheel.

However, if you're short of the "no more thread" line, you're fine, and need do nothing special with double wall rims, though you'll need to file off the excess on a single wall rim where the rim strip sits directly on the nipple head.

As far as tension goes, you need either calibrated fingers (experience), a tension meter, or a comparable wheel (same number of same gauge spokes in the same pattern) to compare your wheel to.

Homebrew01

Any chance you have the wrong size spoke nipple ?

FBinNY 

What difference would that make?

The top of the nipple head is always in the same place regardless of nipple length. Yes, the nipple length can sometimes affect the thread length, but the OP isn't running out of thread, he's concerned that the spokes poke beyond the top of the nipple, which is a spoke length, not nipple length issue.

Homebrew01

The difference is that I mis-read the title, thinking it was "Spoke Pulling out of nipple"

fietsbob

Mass produced wheels , often seen them grind off any spoke coming up proud above the nipple head.

ckaspar

That's ok, I misunderstood the title and thought it was a human body modification post and was wondering what it was doing in the Bike Mech section.

gmt13

If the replacements are just a bit too long, and you think they will possibly cause a puncture, then you can either replace them with shorter ones or grind the ends. Since you are saying that other spokes are now sticking through the back side of the nipple, what proportion of them are doing this. If a lot of them, then you either have over tensioned or all of them are too long. If less than half of them, the offending ones are improperly tensioned giving you a true, but unstable wheel. I'd be inclined to detension all of the spokes, bring them to the point where each has the same number of nipple threads engaged and then retension.

Good luck

-G

bobotech

I wonder if the OP inadvertently altered the dish of the rims to the point where the spokes on the side that got less dished now has poking spokes?

Bill Kapaun

Are the spokes pulling through the rim?

StevePGN10

I don't think that is the case. It was not a matter of only spokes on one side that were exposed. However, I can't say for sure as I don't have a dishing tool.

Bill, the spokes did not pull through the rim.

gmt13, it was not just the two replacement spokes that were poking out of the nipple. Amongst us friends, can I guestimate that it was at least 50% of them, and could have been 75%?

Is there such a thing as overtensioning?

I think I'll take the wheel over to the LBS and discuss the matter with a mechanic who can hold the wheel in his hand and make specific comments.

Thanks to all who responded.

cny-bikeman

You may not have put the spoke back into the proper holes, that would make 1/2 of them "too long."

Al1943

[QUOTE=StevePGN10;13974594]I don't think that is the case. It was not a matter of only spokes on one side that were exposed. However, I can't say for sure as I don't have a dishing tool.QUOTE]

I'm also quizzical about the dish. You can do a reasonable job of centering the rim by reversing the wheel on the bike to see if the rim runs closer to one side or the other. The axle needs to be fully seated in the dropouts when you do this test.