MDReed

I recently had the LBS put a new rim on my hybrid, 700 x 38c, new rim has Schrader hole, old was a Presta. The shop used a grommet adapter and reused my old tube. In less than 100 miles, it failed right where the grommet makes contact with the rubber at the base of the valve stem.
Anyone ever hear of these grommets causing this type of failure? Or is it more likely a tube or installation issue? I'm putting new tires on it, LBS is closed today, and I have a ride tomorrow.
Trying to decide whether to stick a walmart Schrader tube in it, or use one of the Specialized Presta tubes I have here with the grommet, pros and cons of either?

Thanks

Aubergine 

I use those Schrader to Presta adapters on several wheels and have never had an issue with the tubes as a result. However, I *have* had valves fail at the hole, possibly because they had been pulled out of alignment. For whatever that is worth to you!

Iride01 

There are instance that presta valves and Schrader valves get worn or damaged at the boot and spring a leak even when in a rim with the correct hole for them. So your one off experience so far doesn't confirm much. Don't let speculation take you down into the dark depths of blame.

You need to look and see if you see some reason for it to be failing there. Perhaps a sharp edge. Sand it down or otherwise smooth it out. Maybe they improvised a adapter and the hole is still too big. Perhaps the valve boot was already damaged some before it was moved to the other rim and just wasn't noticed.

Rims that have their holes drilled for Schrader have worked well with the adapters and other improvised things put in them to allow presta to fit.

MDReed

Update:
Tire and new tube installed. Once aired up to pressure, the grommet has pushed out from the rim. I'm thinking this is allowing the tube to push in through the inner wall of the rim, and that's how it's being cut. This is the same way the LBS had it installed. Might it be backwards? Should the flange of the grommet be on the inside of the rim? It's currently on the outside underneath the stem nut. I took a picture, but the forums won't let me attach it until I've made 10 posts.

Crankycrank

Yes and yes. Beveled side goes on the outside of the rim if yours look like these.

MDReed

Or perhaps should I switch to Schrader tubes? The tires are Hemisphere Armadillo Reflect and I run 90 psi in them.

MDReed

Thankyou and thankyou!

Iride01 

I've not seen a adapter like that. This is the only picture I found by you. It doesn't show any flange and that part that is under the valve nut certainly shouldn't be in the rim. But there is a little wider edge I suppose you might call a flange. But without seeing the part of the adapter that can't be seen at the moment, I'd not guess.


https://www.bikeforums.net/g/picture/9644535

Crankycrank

Personally I prefer the presta because they're easier to let the air out of when needed and also easier to find in this size but it's not all that important really.

TiHabanero

Yes, the adapter can cause cuts at the valve, however that is "can", not "will". In the past I found sticking with the AV type stem on an AV drilled rim is the wisest choice to avoid problems.

FBinNY 

I'm not a big fan of these plastic or rubber grommets. I buy brass washers that fit the valve, and file or shape them to lay flat in the rim.

I've done this countless times without ever hearing of a failure.

MDReed

Same here. Seems my picture did post, it's a metal grommet with flange/shoulder/whatever it's called. I turned it around with the flange on the inside of the rim. Aired up and staying in place. The other way, it was allowing the tube to push into the cavity between the inner and outer rime walls, and yes, it had started to cut the new tube in the same manner. Two tubes ruined, but problem solved, and lesson learned. This LBS did good work for me for over a decade, but their regular mechanic isn't there anymore, and the owner is wrenching now. This is the third mistake I found in this round of work.

FBinNY 

I suggest you find a new shop. At least until this one finds a new mechanic.

Mistakes happen, but installing
the grommet upside down is unforgivable.

It implies, total carelessness and lack of concern, or a fundamental lack of understanding of how things work.

Either way, anyone who made that mistake shouldn't be working on other people's bikes.