Bicycle Mechanics - Experimenting with Different Tire Sizes in Front and Back

I have a mountain bike with rigid fork that is used exclusively on asphalt roads and pavements for fitness rides. I currently have Continental SportContact 26x1.3 slick tires on the bike. I do also have Specialized Nimbus Armadillo 26x1.5 tires as spares.

I have heard of roadies using 700x25mm tires on the rear, coupled with 700x23mm tires on the front. I'll like to have my Conti 26x1.3 mounted on the front rim, and the Nimbus 26x1.5 on the rear. I am just interested in what kind of ride I can get out of this mix.

The Conti are totally smooth, while the Nimbus has a little thread.

Am I risking anything "safety-wise" here?

Does anybody know what "ride characteristics" to expect?

Thanks for all responses.

Regards,

I have a mountain bike with rigid fork that is used exclusively on asphalt roads and pavements for fitness rides. I currently have Continental SportContact 26x1.3 slick tires on the bike. I do also have Specialized Nimbus Armadillo 26x1.5 tires as spares.

I have heard of roadies using 700x25mm tires on the rear, coupled with 700x23mm tires on the front. I'll like to have my Conti 26x1.3 mounted on the front rim, and the Nimbus 26x1.5 on the rear. I am just interested in what kind of ride I can get out of this mix.

The Conti are totally smooth, while the Nimbus has a little thread.

Am I risking anything "safety-wise" here?

Probably not, but I would put the Nimbus on the front, Conti on the back.

See: http://sheldonbrown.com/tires.html#mixing for the rationale.

Sheldon "Wide In Front" Brown

+--------------------------------------------+
| If you haven’t yet discovered the novels |
| of Neal Stephenson, don’t wait! |
| Start with Snow Crash or Quicksilver |
+--------------------------------------------+

I have heard of roadies using 700x25mm tires on the rear, coupled with 700x23mm tires on the front. I'll like to have my Conti 26x1.3 mounted on the front rim, and the Nimbus 26x1.5 on the rear. I am just interested in what kind of ride I can get out of this mix.

I do the 700x25 in back, 700x23 in front thing on my "sporty" road bike, and it works well. Once I tried a 20mm tire in front, and man did I not like that!!! The front tire had terrible traction despite being a good Conti tire. When I tried to turn, it felt like it would lose contact with the road. I switched that back in a hurry.

PS to Sheldon-- Although I loved "Snow Crash", I thought "Cryptonomicon" was even better. The swim to New Guinea chapter is one read I don't think I'll ever forget. Perhaps that's because I'm a history and math buff...

Probably not, but I would put the Nimbus on the front, Conti on the back.

See: http://sheldonbrown.com/tires.html#mixing for the rationale.

Sheldon "Wide In Front" Brown

+--------------------------------------------+
| If you haven’t yet discovered the novels |
| of Neal Stephenson, don’t wait! |
| Start with Snow Crash or Quicksilver |
+--------------------------------------------+


Thanks Sheldon, I'll try your suggestion, try also with the Nimbus in the back, and then compare and contrast the "rides".

Regards,

Generally with bicycles the larger tire should go in the back because there is more weight on the rear tire.
I run maximum recommended pressure in the rear to reduce rolling resistance and less pressure in the front to improve traction and soften the ride on my wrists, elbows, and shoulders.

Al

Generally with bicycles the larger tire should go in the back because there is more weight on the rear tire.

Al

Negative
See above link

Negative
See above link

The only thing negative around here is your attitude.

I guess my question is why would one do this in the first place? In all my twenty years of riding, racing, and even doing ultra marathon riding, I have never heard of anyone combining different tire sizes on purpose. Sure, there are bikes with different wheel sizes, but that's almost always because of a design spec and the frame is designed accordingly. If you are looking for a better ride I would get a tire with a higher thread count and of course make sure not to forget the talc powder when installing the tubes. I can see, however different tire sizes in some mountain bike racing applications, such as downhill, but for asphalt riding....why?

I guess my question is why would one do this in the first place?

This is done more commonly on time trial setups for the slight aerodynamic advantage of the smaller tire. Continental sells a set of tires called Attack/Force which is a 23 for the rear and a 20 for the front.

Al

Except that the Conti Attack Force is mostly marketing hype to get you and us rich Americans to buy 2 tires at a time, thats why the tread area is thinner (and narrower of course) on the front then the rear so they both wear out about the same time. However having said that read the Sheldon Brown site for more info.