124Spider

Hi,

Our tandem has 32mm tires. Our single bikes have skinny tires. I've been told, several times, that I would be better advised to put a 23-27 mm tube in the 32mm tires, than putting a 32mm tube in. And, having struggled to get the valve block from a 32mm tube into the wheel, I can believe it.

Before I buy another tube, I thought I'd ask here what people think, and, hopefully, get some advice informed by experience.

Thanks.

Mark

reburns

CliffordK

Moderately undersized tubes will work. You can probably use 18-23 tubes in your tandem tires in a pinch, but I'd probably stick with something a little closer like your 23-27 tubes (or a 32mm, or even 35mm tube).

It can be easiest to stock only one or two tube sizes, especially if you are traveling in a group, or have a tool bag that you transfer form one bike to another.

One thing I've noticed. The larger the tube, the more likely you are to get a slow leak with a puncture (i.e. pump and limp home). The smaller the tube size, the more likely it will have a moderately fast leak (for example full to flat in < 5 minutes). My interpretation is that with a large tube, the tube and tire size are about the same, and the hole simply stays mostly shut. With the small tube, the stretch on the tube pulls any hole you get wide open. Perhaps thinner rubber also facilitates this.

If the valves are not fitting well... what width of rims are you using?

For my tube type tires, I mount as following. Mount one bead. Install valve, and press tube up into tire. Push valve up, and install second bead at valve, then pull the valve into place. Then simultaneously work both sides of the bead going away from the valve so I end up with the final mounting approximately opposite the valve.

Tubeless seems more reasonable to end at the valve. I have heard of people mounting working towards the valve, and that may make sense in holding the tube still, but I still like to work away from the valve.

I use Presta on most of my bikes, but have Schrader on my trailer tires (and find myself constantly flipping my pump from one to the other).

Carbonfiberboy 

We run Conti 4KII 28mm tires which measure 31.8 on the bike. We use the 23-28 tubes in them usually, but carry two 19-26 spares because they're lighter, take up less space, and work perfectly well. I don't know why we run the heavier tubes at all, superstition I guess. I doubt a thicker tube flats any less often than a thinner one. The smaller ones sure are a lot easier to get seated into the rim well.

Darth Lefty 

If you look at tube sizes they cover about a 1.5x range of tire sizes. Schwalbe for example would like to sell you their size 16 or 17 tube which cover:

16: 28-622, 30-622, 32-622, 28-630, 32-630
17: 40-609, 28-622, 30-622, 32-622, 37-622, 40-622, 42-622, 47-622, 32-630, 40-635

124Spider

Thanks!

StephenH

Several years back, I got to a ride start, aired the tires up, and pulled the valve stem off one tube when I pulled the pump off. Oops.
Well, I had some new tubes that I had just bought. Pulled one out, and discovered it was for 19-25mm or something smaller like that, and we were using 32mm tires.
So I popped it in anyway, and we took off.
Got about 5 miles down the road, and that tube went flat. Pulled it out, and it was a leak at a seam. So yes, it did seem to fail just from being stretched too much.
So we popped another in, then circle 5 miles out of our way to a Walmart, picked up some other tubes, and proceeded on with the ride.
And finished the ride (300k) with that same tube still in.
So worked for one tube, not for the other.
So based on that one experience, I'd say, don't do that if you have a choice.