semax10

I went to a LBS yesterday and bought a new tire and tube for my bike (trek fx 7.1)...the sales person gave me a Specialized Schraeder valve tube 700 x 28/38 27x 1 1/8"-1 1/2". While putting it on I nicked it so today I went to another LBS and was given a Specialized Presta Valve Tube 700 x 20/28 27 x 3/4" - 1 1/8". What the difference and why was I given to different sized tubes? And which one is the right one?

Specialized Schraeder valve tube 700 x 28/38 27x 1 1/8"-1 1/2"
Specialized Presta Valve Tube 700 x 20/28 27 x 3/4" - 1 1/8"

reptilezs

valve style depends on the rims you have. size depends on the tire and tubes stretch. from memory the current 7.1 has schrader drilled rims

LesterOfPuppets

Maybe you've got 28mm tires so you could go either way. I'd probably even run the smaller tubes in 32s.

I'm surprised the second shop didn't give you Schraeder if that's what was on there originally, though.

semax10

the schreader is the what I had previously...and I told the second sales person the tube and tire...I guess he just wasn't listening.

Thanks

JanMM

Those are two pretty different tubes. Someone wasn't paying attention.
What size are your tires?

Max C.

Some shops don't carry a lot of schrader valve tubes and when they run out they'll give people presta tubes because they will work (at least for a while). I have a presta valve tube as my backup tube on my commuter and I'm not too worried about the difference for that situation. If you do use the presta tube, be sure to tighten down the nut so you don't wear the valve stem. They also sell adapters that let you use presta tubes in schrader rims without issue (not expensive either).

FastJake

The shop was lazy/ran out of the correct tube. If there was originally a schraeder tube in there that's what it should've been replaced with. In practice it won't affect anything except when you pump up your tires you might need 2 different systems (or a schraeder adapter for your presta tube if you use an air compressor.)

It's possible that the smaller presta valve will poke through enough to pinch itself on the inside of the rim. You'll also notice it losing air faster than the schraeder valved tube. I'd say get the correct tube and keep the presta for a spare to carry it with you in case you get a flat.

The difference in widths isn't major enough to cause any problems. Tubes are pretty stretchy.

Myosmith

Tubes stretch, so you can use a range of tubes for the same rim/tire combination. A slightly smaller tube means less to get in the way during installation and less chance of a pinch but it also means the rubber will be stretched slightly more when inflated, which could potentially decrease resistance to puncture. I said "potentially", I don't think in actual practice you are likely to see a difference. The valve issue is another thing. A Presta valve will fit through a Scraeder hole but why mix valve types? I'd exchange it for a Schraeder tube.

semax10

I bought a Specialized Nimbus Armadillo 700x 33c. The sales person said even though my bike came with 700 x35c the new tire is a little thicker and would work best.

goatalope

This is the right one: Specialized Schraeder valve tube 700 x 28/38 27x 1 1/8"-1 1/2"

The other one will probably work fine though.

igknighted

Both tubes will work. There is no "100% right" tube, just ones that fit (and weigh) a little differently. Honestly, with those tires/rims, my choice for tube would be the 700x20-28 with SV (purely because I am more worried about excess rubber folding in the tire that you often get with the wider tubes than stretching them a tiny bit past the rated capacity... I used to run 1.5" MTB tubes in 2.3" tires to save some weight and never had an issue, there is a lot of stretch in these tubes before you are at risk).

To be fair to the second shop, the wall of tubes can be a disaster at times, especially this time of year. I often walk over and grab a tube, then have to go back and get the right one because the one I grabbed was in the wrong spot. If the person who helped you was rushed because the shop was busy, they may not have double checked to ensure that the tube he/she grabbed was indeed the one they thought they were grabbing. Yes they should have double checked, but I wouldn't feel as if they were trying to screw you.

EDIT: If you're concerned, bring the tube back to the shop and ask to exchange it. Be polite about it and I bet they will apologize profusely for giving you the wrong one and swap it no questions asked. If they try to push it on you claiming "it will work", well, while they are technically correct, I would strongly consider whether they have your best interests at heart and avoid them in the future.

nhluhr

I don't know how that's even possible... were you trying to use a tool of some kind to install it? The ONLY tool you should be using is your hand.