Tyres know how

[krisgoss]

Good Evening!
I was wondering if anybody could give me some advice on MTB slick tyres? I have 26" wheels and currently have 1.8 wide semi-slick tyres on them. I am looking to go a bit thinner - good idea before the winter? And would I notice much difference anyway? What would you think is the thinnest I could go?
Thanks for any help

 

[Gerry Attrick]

If you have a look at Sheldon Brown's page on wheels and tyres, you will see a table giving recommended combinations.

I'm not sure what winter benefits you are expecting though.

 

[bikefettler]

Go for a 1.5" or similar and choose something reasonable ie specialised or shwalbe or continental, do some research on the various options as regards the trade offs between duability , puncture protection and lightweight etc to come up with the combination you prefer, over the years I have used allsorts and they all perform well but some are tougher than others I am currently riding, marathon hs 308s, marathon racers specialised nimbus, and michelin road xc`s on various bikes all pretty good IMHO.

 

[jimboalee]

I am running Conti UltraGatorskins 26 x 1 1/8". 28-559.

You will have to retube with Conti Tour Slim 26 x 1.2 - 1.3"
Halfords had a 'Two for one' deal on them a while back, so I bought the entire stock in four branches.

 

[e-rider]

this is a classic question - and i'll upset everyone again with my advice (which is true).

If you go for something very narrow (eg. 26x1.0 up to 26x1.3) and you run them at high pressure (90 psi) it is extremely likely that you will crack the rim of your wheel.

I read about this happening on the web and thought it was bull, so I was happily running my conti sport contacts 26x1.3 at 85psi for 1200 miles then inspected the rim and found about 6 (yes 6) large cracks in the rim! Lucky that the wheel didn't collapse.

Everyone on CC insists that this doesn't really happen! Well, there are numerous accounts on the web and it happened to me; so I believe it!

The problem is that MTB rims are not designed for narrow high pressure tyres.

I wouldn't go below 26x1.6 and keep the pressure below 70 psi.

 

[krisgoss]

Cheers for all of the advice! Much appreciated!
My main concern was about possible grip issues in the rain with thinner tyres, but no one has mentioned it, so guessing it doesn't make too much difference?

Thanks for the advice tundragumski - I would only realistically look at something about 1.5 wide so I don't have to look for slightly specialised inner tubes as mentioned by jimboalee.

I will have another look at tyres now and keep this good advice in mind.

Thank you
Kris

 

[jimboalee]

this is a classic question - and i'll upset everyone again with my advice (which is true).

If you go for something very narrow (eg. 26x1.0 up to 26x1.3) and you run them at high pressure (90 psi) it is extremely likely that you will crack the rim of your wheel.

I read about this happening on the web and thought it was bull, so I was happily running my conti sport contacts 26x1.3 at 85psi for 1200 miles then inspected the rim and found about 6 (yes 6) large cracks in the rim! Lucky that the wheel didn't collapse.

Everyone on CC insists that this doesn't really happen! Well, there are numerous accounts on the web and it happened to me; so I believe it!

The problem is that MTB rims are not designed for narrow high pressure tyres.

I wouldn't go below 26x1.6 and keep the pressure below 70 psi.

I find that difficult to believe.
I cannot imagine a rim manufacturer designing their product to such a small stress limit. They MUST know there will be some aftermarket consumers who will purchase 26 x 1.125 tyres and pump them up to 100 psi. The tyres are on the rack ready to be fitted.
Where is the sticker saying "70 psi MAX".

The rims must have been made from a faulty strip of extrusion.

If anyone has a rim that collapses and the rider is killed as the consequence, American lawyers will take the rim manufacturers to the proverbial cleaners. It wouldn't be in their best interest to design rims that can't withstand 90 psi of pressure in the tyre. If it is seen the rim manufacturers durability test data shows failure with a tyre at 90 psi, they are in deep do-dos.
The difference between identifying a faulty batch and KNOWING the component could fail is a monetary fine or company closure.

Additionally, what about all the rough-stuff treatment MTB wheels get on a downhill course. They should be falling apart everywhere if the metal is that thin.

 

[lukesdad]

Spot on Jimbo. Ive run 1.00 and 1.25 s with 100psi for ten years on the same rims. The reason I use 26s for my winter bike is cos the wheels take the abuse.
I suspect the reason for cracking in these instances if not a faulty batch could be worn rims or overtightened spokes.

 

[e-rider]

I said I'd upset everyone again.

From what I've read and my own experience this appears to be a problem primarily with Mavic rims.

I've said my bit so Ii'll leave it at that otherwise it'll run and run.

 

[e-rider]

...BUT a quote from the first hit from a google search

"Many people ask us about MAVIC rims. We do not sell them because we have seen too many MAVIC rims crack prematurely. The extrusion is too thin and the aluminum too brittle. "