Mountain Bike Reviews Forum banner
1 - 20 of 30 Posts

·
Registered
Joined
·
100 Posts
Discussion Starter · #1 · (Edited)
cracks by nipples= new rim

I was just cleaning my rim and notices that my rim has cracks by the nipples. the cracks are small but theyu go out about a half inch and it allmost every nipple from the drive side of the rim. its got the metal eyelets on it but it still has cracks evry where. I just had the rim laced up last april. Ive had the stock rim do the same thing kinda. It cracked on the inside of the rim(underneath the rim tape) between nipple holes.
Any ideas on what Im doing wrong? its a rigid and Im a big guy, I think that might be some of the problem. Ive also broke a lot of nipples off the old rim before i had the new rim laced.:madman:
 

·
Registered
Joined
·
1,902 Posts
Which rim & hub?

We've had a fair number of light-weight rims fail at the spoke hole - it's a fine line tensioning some of the light race rims.

However, several year ago (~10) every Mavic rim was cracking at the spoke hole. Every OE wheel showed crazing at the eyelets when newly built, and cracks after a year. That lasted almost 3 years before they fixed it.

Here's what a new wheel looked like delivered to the lbs:


Here's what it looked like after 2 year - longer than it should have been ridden:


No warrenttees were available then.
 

·
HopHeads, Unite!
Joined
·
395 Posts
Wow, you're cracking Gordos? What is the spoke tension? Have you talked to Salsa?
 

·
Trail Tire TV on blogger
Joined
·
4,237 Posts
well, personally, I wouldn't keep riding on them...!! :eek:

talk to the guys who laced them... you said he stock set was doing it too so it's probably not the re builders fault but they might be able to help ya... talk to salsa... no rim should do that!!

you are kinda a big guy. I'd say try going up to a tad stronger rim..might be a tad heavier but I don't know about you but I'd rather ride with a bit of weight and not have to walk out (or have a ambulance ride)

I've gone to the Velocity Blunts. super strong, not too heavy, wide foot print (thought not quite as wide as the gordos)... but they just came out with the P35's.. I'd give them a shot over getting the slasa's again... then there cracks are kinda scary!!!
 

·
Registered
Joined
·
919 Posts
The cracks are certainly not good, but I also think not likely to lead to catastrophic failure during normal riding. The cracks will tend to make the spokes lose tension, which will weaken the wheel somewhat, but they're not likely to pull out. Remember that the bike and rider is supported by compression (reduction in tension) of the lower spokes. I'd definitely keep an eye on the cracks, and work on getting the rims replaced, but I probably wouldn't stop riding those wheels right away (the Gordos, not the rim in post #4).
 

·
Registered
Joined
·
100 Posts
Discussion Starter · #11 ·
thanks for the info. I went out for a couple hours last night on the rim, no changes in the cracks. I dont blame the gut who laced up the rim or salsa. i love my salsa bike but have had a nuber of problems with these wheels. Was looking at the p35 or the chukker from velocity. any other rims that might be a good idea for me? have been thinking about new hubs too so maby the 36 hole route might be my next step. Would also like to have a set of lighter weight rims for raceing(any thoughts on that?)

again thanks for the info
 

·
Banned
Joined
·
7,930 Posts
Seeing the crack right next to the stem hole, which is where most wheel builders start to index to tension the spokes, and the possibility that that is the last spoke, with a potential "high spot" that has to be pulled in to keep the wheel round, I'm of the belief that the wheel may have been over tensioned also. I weigh 225, ride a hard tail too, and I've not experienced that type of failure yet, knock on wood. Are the stress crack spokes all on the drive side spokes, or the brake side?
 

·
Registered
Joined
·
207 Posts
fallzboater said:
The cracks are certainly not good, but I also think not likely to lead to catastrophic failure during normal riding. The cracks will tend to make the spokes lose tension, which will weaken the wheel somewhat, but they're not likely to pull out. Remember that the bike and rider is supported by compression (reduction in tension) of the lower spokes. I'd definitely keep an eye on the cracks, and work on getting the rims replaced, but I probably wouldn't stop riding those wheels right away (the Gordos, not the rim in post #4).
The bike and rider are supported by the upper spokes, (increase in tension) that are essentially holding up the hub. You can't "compress" a spoke while riding, it would simply push up into the tube/tire. There is nothing behind it to compress it against.
 

·
Registered
Joined
·
469 Posts
This was my Mavic problem.
This rim was ridden hard in the Alps and Ardennes for 3 years. I weigh in about 80 - 85kg.
Don't know if this can be called a real problem. Unless it happens in the middle of nowhere :eek:

The Gordo's are toast. Is there salt involved ?
 

·
transmitter~receiver
Joined
·
9,334 Posts
jager7 said:
The bike and rider are supported by the upper spokes, (increase in tension) that are essentially holding up the hub. You can't "compress" a spoke while riding, it would simply push up into the tube/tire. There is nothing behind it to compress it against.
uh oh...
fallzboater is right. it is a very well understood phenomenon, even though it is counterintuitive.
the loads on wheels are supported by the spokes on the bottom. it has been debated exhaustively on this forum as well as many others, probably because it is a somewhat tricky concept that people don't see right off the bat, but it is a fact.
that's all i'm going to say about it, for fear of derailling yet another thread.
if you'd like to learn why it is the way it is, do some research on this forum (here's a start) as well as reading about prestressed structures.
 

·
transmitter~receiver
Joined
·
9,334 Posts
mtnbiker72 said:
Those cracks appear to be from excessive spoke tension, which puts a lot of strain on the hub flanges, nipples, and rim. Since you are riding rigid and are a "big guy" you may want to look at going 36 hole, 4x to reduce spoke tension and distribute stress more evenly.
agreed across the board.
 

·
Bedwards Of The West
Joined
·
5,451 Posts
1 - 20 of 30 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top