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OK to replace just the rim?(20 posts)

OK to replace just the rim?Scy
Nov 12, 2001 8:49 PM
I killed my rear rim on a pothole at 30 mph. So I got two choices; either get a new rear wheel or replace the rim.

One of my LBS reps told me that he could replace just the rim with one of the same profile; this way I can use the same spokes/hub. This will cost me $40 for the rim (a Campy Omega) and $20 labor. I'm thinking of doing the changeout myself for the experience. If I screw up, I can just have the mechanic finish the job.

A rep at another LBS told me that I would need to change the spokes because they would eventually break after being detensioned and then retentioned. The spokes would only be another $25, but it's going to be a pain changing them out of a rear wheel and relacing them.

So, can anyone out there tell me if it's OK to change the rim w/o changing the spokes. Thanks all.
re: OK to replace just the rim?TheMaxx
Nov 12, 2001 9:58 PM
How old are the spokes? It should be okay, as long as they are still in good shape.
You could probably do it yourself too. Just tape the new rim to the old one, loosen all the nipples, then just move them over to the new rim one by one. Then just tension it. If you were planning on trying this, I hope you have some idea how to tension a wheel.
should be ok..Jekyll
Nov 12, 2001 10:21 PM
I just did the same deal with a set of MTB wheels from a bike that got trashed when my car got rear ended.
My rims were shot from the wreck but the bike only had 38 miles on it so it seemed a shame to toss the spokes. Just inspected them to make sure there were no serrations, notches or kinks and relaced the hubs and spokes to set of Mavic 317's I had been keeping around for a winter project.
The rebuilt wheels are fine. I use them on my dually and beat the hell out of them - a dozen or so hard rides later no problems.
I would guess if your spokes are pretty new I'd go for it - if you've already gotten you money's worth out of them then it might make sense to buy some new ones....
YepJofa
Nov 13, 2001 1:49 AM
Hang onto the spokes and change the rim as another respondent said: tape the new rim next to the old and go round spoke by spoke. Bringing the new wheel to tension is the only tricky bit (apart from stress-relieving, which you won't have to do if its been done already). You might even have as much fun as Len J reports below.

Shops often want to replace spokes in unfamiliar wheels, because they can't testify for the history of the old ones and subsequently don't want to guarantee them. This is fair enough but of no benefit to you. Wheels bear loads by reducing tension not increasing it: your spokes are no more likely to fail as a result of this crash than they were before.

Good Luck

Jofa
doesn't the load do two things.....Woof the dog
Nov 16, 2001 12:19 PM
to two spokes opposite of each other. The ones at the bottome below the bracket detension, while top ones increase in tension? thanx
Woof
you'd think so...Jofa
Nov 18, 2001 3:54 AM
...wouldn't you, but it doesn't work quite like that. The bottom spokes reduce tension and all the others remain unchanged (unaware, if you like, that anything happened). You can prove this to yourself by plucking spokes at the top and bottom of the wheel before and after a heavy friend sits squarely on your bike. The bottom spokes will ring a lower tone, others stay the same. Be sure to try it with a few different pairs to take into account the varying resting tension throughout the wheel.

We tend to want to imagine a wheel as a rigid hoop with a membrane of elastic spokes, within which the hub moves around relative to its loads, affecting spokes on all its sides. This visualisation is however entirely wrong, though a lot of people have difficulty in dispensing with it. In fact the spokes are by far the strongest component of a wheel, and it's the rim which does the bending- it flattens out at the bottom of the wheel.

If you find it difficult to visualise, imagine turning the wheel so that it lies flat, and secure the hub from one side in a vise. Then press in toward the hub on one side of it- simulating load from the road. It should be obvious now that the spokes on the far side from you are oblivious to what is going on.

This happens even when the wheel is overloaded to failure in a crash. The rim will fold up or 'taco', which results in total loss of tension for all spokes, before any see an increase in tension.

truth is stranger than...

Jofa
ProbablyKerry Irons
Nov 13, 2001 5:28 PM
Unless the spokes got really stressed in the crash. But it sounds more like you dented the rim on the pothole, which wouldn't have put a terrible load on things.
Yes, just replace rimBlair
Nov 13, 2001 6:14 PM
Are you using the same type of rim?
if yes, then reusing the spokes will work well.
Or you can check the effective rim diameter (E.R.D.)and compare.
www.sheldonbrown.com has great online wheelbuilding instructions. and links to good spoke length calculators.
I disagree...jaybird
Nov 14, 2001 5:55 AM
I have always used new spokes when rebuilding a wheel. For me, the cost is worth the added confidence. This is not to say that it can't work, just my .02... If you are set on keeping your old spokes, inspect them carefully especially at the bend.
Chicken Littlegrzy
Nov 14, 2001 1:00 PM
Just what exactly makes the spokes suddenly no good when one considers that they were fine until yesterday? Jobst Brandt specifically addresses the issue of re-using spokes and says it's not a problem.

If the wheel/spokes were built right and not abused then they'll be well under any elastic limit of fatigue life. In fact stainless steel has very high toughness (area under the stress strain curve) and can take a lot of abuse. Now if you're building new wheels b/c the spokes are always breaking then go for new ones. Ultimately what's the worst that can happen on a ride - you break a spoke BFD. It's not like the wheel is going to suddenly fly apart and leave you in some Willey Coyote situation.

The biggest problem to reusing spokes is being able to unthread and rethread the nipples. Sometimes it's just way too much hassle trying to get them apart and then be able to adjust them once you put them bac together. Been messing with some 28u straight pull mavic Crosslink disc wheels and I'm getting ready to just chop the spokes - way too many are siezed and I can't keep the spokes from spinning since there is no J bend in them.
Chicken LittleTheMaxx
Nov 14, 2001 1:55 PM
If the spokes are bad, they will start breaking when you re-tension them on the new rim. If they start popping as soon as you tighten them, I would go with new spokes.
Really?grzy
Nov 14, 2001 2:37 PM
If they start popping as soon as you tension them what choice do you really have?

Are you trying to knock me off as master of the obvious?
Chicken Littlejaybird
Nov 15, 2001 6:15 AM
A nice heavy gauge wire cutter is the only way I remove spokes. To me it is not worth the time or effort. Spokes are cheap and I build my wheels myself.

Do you reuse nipples too?
Chicken armsJofa
Nov 15, 2001 7:00 AM
I find it takes more time and effort to relace a wheel from scratch, and later to correct its spoke-line and stress-relieve it, and suffer the subsequently sore hands and forearms, than it does to move the existing spokes over one by one. I know these spokes are already stress-relieved because I did it myself, added to which none of them have broken in years: new ones present an unknown quantity, and mean starting all over again. Perhaps you don't finish your wheels properly and that's why you have such little confidence in their durability.

Jofa
Chicken armsjaybird
Nov 15, 2001 8:26 AM
I've been building wheels for 12 years for myself and others and their durability/workmanship has never been questioned. Any type of metal with tension on it will fatigue over time, which is my main reason for opting to use new spokes and again, spokes are cheap...

How do you get sore hands and arms from building wheels? Toughen up...

I do not know of any pro team mechanics or riders that reuse spokes from damaged wheels.
Chicken legs tooJofa
Nov 15, 2001 9:29 AM
I get sore hands and arms from stress-relieving the wheels. Maybe you are very strong and can do this without breaking sweat. I am not and can't, and I chided myself about that in the title (chicken arms), so you don't have to but are of course welcome to.

I'm sure your wheels' workmanship is fine... you put their durability in question yourself, by implying that you have suffered spoke breakages after replacing a rim only, which events made you decide to exchange all the spokes in subsequent rim replacements.

I have no idea about the policies of pro team mechanics regarding rim replacement, but I don't see how it's pertinent to this issue.

Limp-wristedly

Jofa
Chicken legs toojaybird
Nov 15, 2001 11:40 AM
sorry, sarcasm is tough to detect in writting. I am curious how you stress relieve wheels that makes it such a chore.

I haven't suffered any spoke breakages after replacing a rim only, I have always used new spokes regardless. Partly because I dont want to risk anything (most times, metal fatigue, in any product, is not noticeable from a visual inspection.

My reference to pro mechanics was just to show that it is common to use new spokes on every wheel. I am good friends with a couple of former pro team mechs and it was they who told me not to trust used spokes. I guess it has just become a habit and standard operating proceedure for me.

I also replace all the bearings when I rebuild a hub that is not sealed...

Ride on...
J.
Chicken legs tooTheMaxx
Nov 15, 2001 11:56 AM
wow, jaybird. How lucky we are to be in the presence of such a strong armed, 12 year experienced wheel builder. Nobody doubts your wheel building skills, just as I expect you needn't doubt mine.
We were trying to help the guy who started this thread. He probably doesn't know how to lace a wheel, but you can replace the rim easily by not unlacing it. I also doubt that he is a pro rider, otherwise he wouldn't be in this situation. Just take it easy. Are you trying to prove something?
And I also replace all the bearings when I rebuild a hub that is not sealed. BFD
Chicken livers, friedJofa
Nov 15, 2001 12:49 PM
I stress-relieve spokes by squeezing parallel spokes together. I know of no other method which applies enough excess tension to have an effect. How do you do it?

If you've never suffered breakages as a result of old spokes, why go to the effort and expense of new ones? Try old spokes! I bet they'll work fine. I got taught wheelbuilding by an ex professional team mech, as well: I a callow youth, he regaling me with tales of how he changed riders' wheels leaning out of the TVM car at 20mph, while he wedged his wheels in drawers or walked over them or whatever... all of it gratuitous posturing, and I nearly fell for it.

I use the old bearings, as long as they're still shiny... aah...

Jofa
Oh yeah? What ifMuncher.
Nov 15, 2001 8:41 AM
You were chasing roadrunners for the training (lastate threshold) value, and, just as you were closing down ready to put a tyre stripe down his back - "ping" - there goes a spoke, and the wheel just goes out of true enough to rub on your finely adjusted brake blocks, causing a loss of speed at the crucial moment - you miss the 'runner, and the train you were just about keeping ahead of (for high cadence motivation) mows you down from behind.

Eh? Eh?

That's EXACTLY a Wiley Coyote situation.

You have to be aware of these dangers....