Advice Please On Rims & Tyre Pressures

Smiffy151

Hi Guys

I've just had a set of custom wheels made for my MTB these are for a quick swap from the std MTB wheels and tyres to a set of wheels with semi slick or commuter tyres on.

The wheels are built on Mavic 421en Disc Rims which state that the max psi is 43 but the continental travel contact tyres want 80 psi. The tyres are 28 x 1.6 or 42-622 and when I look at Mavic website their tyre pressure chart although doesn't list 1.6 or 42 has a near as damn it guide of around 80 psi max...?

I'm confused, do you think it's safe to use these tyres with these rims?

Thanks

cooldad

You would never, ever need 80 psi on an MTB.
I run mine at between 25 and 35psi and I'm not slim.

Even the skinny Contis on my commuter are around 40/45psi

cooldad

ps changing wheels is rarely a quick swap. Generally gears will need indexing and brakes centred.

mattyfez

As above, 80 PSI will be the max pressure for that tyre, which is more like what you'd use for road racing.

You'll probably find around 40 PSI is plenty hard enough without sacrificing comfort.

The Rookie

I run 26x1.6" Conti on the front of my commuter and I run it at 80psi, I used strava to check rolling resistance over a downhill segment (rolling from stationary start) and am using the max 80psi as it shows a resistance reduction from 70psi (didn't test 75) and a lot lower than at 40.

Smiffy151

cyd190468 wrote:

If you want the swap to be quick you may need to shim the discs so both wheels are aligned the same at each end. Then it'll just be a matter of a couple of turns on the rear barrel adjuster for gears in required. Once you swap a few times you learn the difference so you can do it before riding.

That's another thing i'm concerned about, how much fettling will it require to just swap wheels, maybe I should of just gone with two bikes rather than custom wheels....!

The Rookie

Having the same make of hub will help, some manufacturers don't quite follow the 'standard', so using the same make means at least you'll only be dealing with tolerances.

Smiffy151

Thanks everyone that added their advice really appreciate your help

Smiffy151

Smiffy151 wrote:

Hi Guys

The wheels are built on Mavic 421en Disc Rims which state that the max psi is 43 but the continental travel contact tyres want 80 psi. The tyres are 28 x 1.6 or 42-622 and when I look at Mavic website their tyre pressure chart although doesn't list 1.6 or 42 has a near as damn it guide of around 80 psi max...?

I'm confused, do you think it's safe to use these tyres with these rims?

Thanks

My original question about tyre pressures and rims is still of a concern, do you think it's ok to run with the rims and tyre pressures as I said Mavic website gives a max pressure for specific tyres but the rims say 43psi max? Still confused as to whether or not it's ok to inflate to the stated pressure of the tyre, this is the link here http://www.mavic.co.uk/rims-mtb-en-421-disc and you can see a max tyre pressure link

Thanks

cooldad

Those are quite fat rims and I'd be more worried about trying to run skinny tyres. Recommended tyre width is 2 to 2.5.

The Rookie

I would think they would run a 1.5" OK, Road rims are getting wider and Sheldon Brown lists a 35mm tyre (1.5" is 38mm) as OK on a 21mm rim. I wouldn't run a 1.5" off road tyre on it though which I think is the basis for the Mavic recommended widths, no rim protection from rock strikes.

Of course the wider the rim the greater the force the tyre pressure applies, as the number of square inches has gone up!

Smiffy151

Thanks everyone for all your advice

cycleclinic

Try 50 or 60 psi max in those tyres on your rims. You will be fine. Most folk fret over this sort of thing there is no need to fret. In the tyre wider than the rim it will fit and run what ever pressure you like bit most people use pressure that are too high. The ride and geip improve as you drop the pressure.