dwxpub

Hi all. I'm a heavy rider - 275 lbs - starting up again. I have a Jamis Exile, maybe an 05. I'm relatively new to this, and I have a small problem. I've got standard, mountain bike tires, and I've been thinking about replacing them with a more general purpose tire, as I'm doing much more street riding.

My problem is that when I sit on the bike, the rear tire flattens out. Now, I'm not sure if this is because of the pressure in the tire (could be down), or my weight (more likely). And when it gets this flat, I just don't feel safe on it.

Any ideas on what I should do? Thanks!

DieselDan

Tires do this to everyone.

asherlighn

Pump them up!

Sprocket Man

Hopefully your pump has a pressure gauge or you have ready access to one. The sidewall of your tire should have the recommended pressure rating. Pump it up to a pressure that's within the recommended range. If anything, you probably want to go towards the upper end of the range to help prevent a pinch flat.

DieselDan

I deal with people that think tires should be completely round when they sit on a bike. That is completely unrealistic. The laws of gravity and chemistry won't allow that to happen. Don't try to tell me a tire with a 2" section of the bead blown off was caused by a defect or a piece of glass.

dveary

Not that you can't post here, but you will get a lot of useful info from the Clydesdale/Athena section which deals with people 200 lbs and more like you and me.

john bono

Actually, the tire should have the MAXIMUM recommended pressure rating if you are a clyde. Maybe even 5 lbs above the maximum. I kept my 125 psi rated 700/25s at the max+ to avoid pinch flats, and I keep my 700/28s at the maximum 100 psi for the same reason.

Mr. Beanz

Ditch the standard mtb tires. They don't take much psi at all, 40-60(?). If you want to lose the squishy feeling, slap on some 26 X 1.50 tires. Slicks tires with 90 psi feel much different and stiff.

Unless you're riding dirt, these will roll fast too.

I had a buddy riding a hybrid at 275. 700x28 tires (Vitorrio Rubinos, I think). He was a strong rider and kicked major azz! Also had 2 roadies so no, you aint too big!

deraltekluge

First step is to check the pressure in your tires. More weight on the bike flattens the tire more. Think of an idealized situation of a slick tire with no stiffness, so that the air pressure provides all the support. A rider weighing twice as much will flatten the tire to the point where the total size of the contact patches (front and rear) with the ground is close to twice the area. If you have a 135 pound rider and a 30 pound bike, the total contact area with 50 psi is 3.3 square inches. A 270 pound rider would flatten the tires to the point of having 6 square inches of contact area. (Remember that this is a much simplified and idealized explanation.) If the tire pressure is only 30 psi, a 270 pound rider would flatten the tires to the point of having 10 square inches of contact area.

Seamus

This is the right advice. Nashbar has a 26 x 1.25 90psi tire that would be perfect for you. Get a good floor pump with a gauge, and pump them up to 90 or even 95. You'll be flying. Oh, and the nashbar tires are $9.99 each.

Jim

Mr. Beanz

I used a Specialized version about $20 each. Fast and tough, never a flat in two years,streets and trail.

Bill Kapaun

If you don't have a suspension fork and a lot of pot holes, you might want to not go lower than 26"x1.50".
I find that to be suitable for my 240+ lbs. on my 86 Rock Hopper. I use the Serfas Drifter-