MTB bike rim leaking at the joint.

[River Rat]

I noticed today that my tubeless WTB Speedisc is leaking through the rim joint. It is small and I think the sealant might seal it off. I suspect that it might be that the rim tape is old and defective so I am going to replace it.

 

However, I am a little concerned that there maybe a bigger problem than just the rim tape. Has anyone else experienced this?

[dirtrider]

Same thing happened to one of my very old and abused Alex rims . It started to leak at the joint but after a fewmore miles the rim started to loose shape quickly and I replaced it before the thing collapsed on a DH .

[River Rat]

Dirt Rider the rim seems to be fine and is holding its shape quite nicely or do think that it is only a matter of time before it breaks down completely?

Edited December 23, 2010 by River Rat

[dirtrider]

Like I said a did a few miles after discovering the fault in the rim joint but the gap eventually grew to big for comfort and no amount of spoke tuning would get the rim 100%

[River Rat]

Thanks Dirt Rider, I guess I have choice to ride it until becomes unrideable or replace it now. I think I am going to replace the rim tape and see how it goes.

[River Rat]

Just an update I replaced the rim tape and paid special attention to the joint by placing a nylon strip across it. Rim joint leaked a little for a day or so but now seems fine. I hope that problem is solved

[Johan Bornman]

Like I said a did a few miles after discovering the fault in the rim joint but the gap eventually grew to big for comfort and no amount of spoke tuning would get the rim 100%

 

 

What sort of fault did you discover in the rim joint? Rim joints don't usually fail by themselves since the rim is under compression. In the old days rim joints weren't welded, just plugged and that produced no problems other than a thump-thump as you braked and the pads went over the joint.

 

A gap that grows can only be due to diminishing spoke tension.

Edited January 1, 2011 by Johan Bornman

[River Rat]

Johan, I could not distinguish between the gaps of the non leaking and the leaking rim. In fact only noticed sealant coming through when I took the pressure to 65 psi. The rim itself seems true to the naked eye.

 

Do you suspect that there may be a spoke tension problem?

[Johan Bornman]

Johan, I could not distinguish between the gaps of the non leaking and the leaking rim. In fact only noticed sealant coming through when I took the pressure to 65 psi. The rim itself seems true to the naked eye.

 

Do you suspect that there may be a spoke tension problem?

 

No. The rim was not perfectly welded and now it leaks. I suspect your rim tape and/or valve seat is dodgy. Sometimes the sealant comes out spoke holes, it just depends which hole the sealant and air prefers.

 

I commented on a situation I cannot picture. Good spoke tension, yet the joint gap opens up. This is not my experience. I've built many wheels with older rims that weren't welded and as you increase the tension, you can see the gap close.

 

Even with poor spoke tension, a rim is under enormous compression and never fails at the joint since it is always under compression. However, it is quite conceivable that it can still leak there.

 

In your case I would simply redo the tape.

[Mechanick]

Hi Guys

 

I had the same thing happen to my fiancee wheel. It was basically a new bike, probably 150km max done on it also had leaks at the rim join. Johan, not sure if the spoke tension on wheel was not correctly done initially.

 

I did not redo the tape, but simply pumped the wheel so hard to force the stans into the leaking area and the next day it leaked. Did a three day race that same week and had no problems with the wheel.