The Fat Cyclist Gives Me An Idea About Flat Tires
Before I had a road bike, I ran pretty low pressure in my mountain bike tires. I bounced around less with the pressure at 35-40 psi than with it closer to the max of 60 psi; smoother rides were more comfortable, so that’s what I did.
Then I got a road bike. Soon I was no longer a mountain biker, but a roadie who also had a mountain bike. Consequently, I brought my roadie habits to the mountain bike. I used to ride the mtb with baggy shorts and jerseys. Now I were the tight stuff. I used to wear a camleback. Now it’s bottles. The ginormous, backpack sized, saddle bag has been replaced with a pouch barely big enough to hold a tube and a patch kit. I stopped driving to trails and just rode the bike to them.
All those changes were for the best. They make the ride simpler and more fun. One carry-over, though, might be the reason I have had three flats on my last two mtb rides: Super high tire pressure. Like I said, I used to run at about two thirds of the max psi. On the road bike, though, I’m running a rock hard 110-120 psi. Higher pressure means less surface contact which means more speed (and also longer tire life). That’s good for the road, and, so I used to think, it must also be good for the trail. Turns out, as the Fat Cyclist informed me, maybe not so much.
On the trail, whatever speed you gain with lower rolling resistance you are going to lose bouncing over things and losing traction in corners. That is, if you lower the pressure, the bigger tire area in contact with the trail might slow you a bit, but it also gives you more control – and thus speed – over obstacles and through corners. Also, lower pressure helps avoid flats. I suppose it’s just like a balloon. Inflate one all the way and the slightest touch with a sharp object makes it explode. Inflate the balloon half way, though, and you can poke and prod it quite a bit before it bursts.
Ditto a bike tire when, for instance, it rolls over one of the infamous briars at the Stoner Trails. Those stupid things have flatted me three times in my last two rides. With that many flats, I would usually suspect a problem with my tires or my rims, like a piece of glass stuck in the tire. These have all been in different locations on the tubes. They’ve also been on both wheels. So I know the problem isn’t debris in my tire or defective rim tape. Still, the frequency of the punctures is too great to be just bad luck. And now, thanks to Fatty, I think I know what the problem is: Too much tire pressure.