I am going to put Schwalbe marathon Supremes on my QNT.

I am putting 20 X 1,60 on the front but am not sure what tubes I should be using 20 X 1.75 or 20 X 13/8.

Some advice would be appreciated.

Steve

i'd go for the former.

We went for big apples on the rear of our QNT's - we had suffered from rear wheel spin on steep wet hills (Wales) and some gravel. The apples have been very successful. There are kits from ICE to move the seat forward (for short legs) and back to move more weight over the rear wheel for off road work and I guess very long legs

Yo, I put on Schwalbe 1.5 tubes with presta valves. Always used Presta, you can always flag down a roadie with a better pump.
The tyres are supreme, you'll find them fast and tough, Tested!

Thanks for that.

I am in Denmark and You don`t see Presta valves or bike pumps that will fit them over here.

Steve

With Supremes, I am using Schawlbe SV6 tubes which are marked 28/40 - 406. These are the narrower tubes and I have no problems with them - and they are easier to fit - wide tubes are just that little bit harder to get back in - mind, tubes sre much easier to fit than tyres, so does not make much difference - I have ran wide tubes in narrow tyres and very narrow tubes in wide tyres, and even the wrong size tube (for 451 tyres in 406 tyres) with minimal problems - just have to be sure the tube is all in the right place when fitting the tyre.

John Turvey

Steveindenmark Wrote:
-------------------------------------------------------
> Thanks for that.
>
> I am in Denmark and You don`t see Presta valves or
> bike pumps that will fit them over here.
>
> Steve

I bought the 20 X 1.75 and have just opened the box and they have a Presta valve.

My problem now is the Presta valve is too big to go through the rim of the wheel. Should I drill the wheel rim to get it in?

Steve

Odd... Presta are usually the thinnest valve stem...
You sure you don't mean 'Schraeder'/'AV'/'Car Valve' which are the larger diameter ones?
Check the pictures here:
[www.sheldonbrown.com]
I have successfully drilled out presta-drilled rime to take Schraeder valves as I prefer them. But you may be best not messing with them if you don't have to.
Rob

What Rob said ^^^^^^.

I can assure you BTW that both types of valve and pumps to match are available in Denmark and indeed the rest of the developed world! Narrow 20" tyres with Presta valves may not be so easy to come by in local bike shops (they tend to stock wider 20" tubes with Schraeder valves for BMXs) but specialist recumbent/folding bike dealers will have them, and any competent dealer will be able to get them for you to order. And most modern pumps now come with fittings to suit both valve types.

You are all totally correct and it is the Presta valves that are more commonly used here.

Having said that I cannot find 20 inch tubes with Presta valves but I would rather have them with Schraeder valves anyway so I will drill the rims out to fit the Schraeder valves.

Thank you for the advice.

Steve

We can mail out 20in with Presta if you can't get them locally, but with innertubes you are likely to need them urgently and on a regular basis so you are probably better off with a local supplier and the more common Schraeder valves...
I found drilling a rim quick and easy, they're nice soft aluminium. Take your time and watch your fingers!!! Make sure you tidy up the edges of the hole, especially if you use the more common rubber collared Schraeder valves. Schwalbe ones have metal valve stems and I prefer those as they tend not to get damaged/cut.
Sheldon says you'll need a 21/64ths drill but that sounds like an unlikely find in modern Europe!
There are little plug-in adaptors to allow you to use Presta valves in the new bigger holes if you need to go back to them. I don't know a supplier though.
Rob
wrhpv.com



Edited 2 time(s). Last edit at 29/04/2010 04:38PM by RobH.