cprice404

Hi, apologies if it may seem that this thread would be more at home in the "Cyclocross" Forum... but I use my cross bike for commuting and am not much of a racer, so after much deliberation I decided to post here.

I recently bought my first "real" bike. I've been using an old 40+ lb tank of a MTB for commuting for the last 5 years or so, and after borrowing a road bike from a buddy for a few days I finally decided to treat myself to a new bike a bit more suited to my riding conditions. I settled on an '07 Lemond Poprad (mostly for the steel frame + disc brake options) and I absolutely love it.

BUT... I'm getting ready for a 100k ride that is coming up in a few weeks, which will be about twice as far as I've ever ridden in one ride before--so I want to make sure I'm prepared. Amongst other preparations I decided now would be a good time to pick up a few spare tubes.

I've never had ANY problem finding tubes for any bike I've owned in the past so I didn't pay a lick of attention to the availability of tubes for the tires on my new Poprad when I made my decision to buy it. Now that I've started looking for them I'm realizing that they are an unusual size and I don't know where to find tubes. The tires are 700x34 and the stock tubes have a long-stem presta valve. I've checked 3 local bike shops and it seems like all of the major brands of presta tubes that they stock are 700x28-32 or 700x36+. There seems to be a gap between 32 and 36, which, unfortunately, is where my tire falls. I've also spent a bit of time poking around the web looking for online bike shops, and the tubes I've found on those sites seem to be sized in the same way (i.e. nothing available that says it'd fit a 34).

Now, the guys at 1 LBS tried to sell me a 32 tube and said it'd be fine, and the guys at another LBS tried to sell me a 35 and said it would be fine. Maybe either would be fine but I'd feel much better if I'd gotten a consistent recommendation, or if I could just fine some that claimed to fit a 34. It seems like there are a fair number of cyclocross tires out there that are 700x34 so it doesn't seem like this ought to be that hard.

So... long rambling preamble having been completed, here are some questions that I have, the answers to any of which I would be tremendously grateful for:

1) Does anyone know where I can find a tube that is actually rated for a range that includes 700x34?
2) Regardless of #1, Is it OK to use a 700x??-32 or 700x36-?? tube on a 700x34 tire?
3) If so, is there a reason why going with the undersized would be wiser than the oversized, or vice-versa?
4) While I'm seeking tube advice--does anyone have any affinity for a particular brand or style of tube? I'm probably looking for something in the "intermediate" range between minimum weight and maximum durability. I'm commuting and not racing so obviously avoiding flats is the most important concern, but I'm also still relishing the performance difference between my new bike and my old MTB so I don't want to go over the top on tube durability.

Greatly appreciate any insight anyone can share... and if I ought to have posted this to the cyclocross forum instead, please let me know!

dobber

This one has a range of 20mm https://aebike.com/page.cfm?PageID=30...ils&sku=TU9209 - Good tubes by the way, I run em on both my Cross-Checks.

Them there inner tub things is stretchy. A 32 will work fine in a 34. And a 36 likewise. Now too big a tube will give ya some problems stuffing it all in there. And too small of a tube might stretch out a bit and be more prone to flatting. But in general if your within 2-3mm you'll be fine.

Fact is, there is no guarantee that your 34 tire actually measures 34mm in some way.

And I usually get what ever is on sale. They all come from China anyways.

M_S

I've gotten by using a 23 tube in my 28 road tires, and a 28 tube in my 35 'cross tires. If you pump up a tube quite a bit while it's outside of a tire, you wil see that it flexes a LOT, as the poster above said.

As far as long valve stem...do you need it? I didn't think that the Poprad had wheels with a deep rim.

gosmsgo

It really does not matter too much. I have had students who had 26 inch tubes in their 28 (700c) wheels.

Rubber stretches.

Conveyor Belt

Using the 36 will give you a bit more rubber and puncture protection. A bit. not a lot, just a bit.

I-Like-To-Bike

1) https://schwalbetires.com/bike_tires/tubes
2) Yes. Marathon brand AV17 (Schraeder valve) or SV17 (Presta Valve) fit 28-40 mm tires. $5.85 each
3) See 2)
4) Yes. See 1) and 2)

cprice404

sweet, thanks for all the advice.

i don't think the poprad's stock wheels would actually require a long valve stem, but the tubes that it came with have one. they stick out quite a ways so i think i could get away with the regular ones.

-=(8)=-

Ive used a 23 in a 32

No problems of the real, non-hypothetical variety, either

JustBrowsing

Tubes are stretchy. Hell, I've put a 20" BMX tube on a 26" wheel. Seriously, you should be fine with either the 32 or 36 tube. Or if you really want to make sure you're okay, get some of these Vittoria tubes rated for 28-47 tires.

sumguy

Is tube size dependent on rim or tire size? Hybrid has 700x28/35 rims (according to the sticker) but 700x40 tires. Carry a 700x35-38 tube for emergency flat. Just curious.