Mountain Biking - The Biggest Posse of Tire Questions In Awhile!

I've bought and installed a set of Bontrager SS Revolts (http://pricepoint.com/product286.html) a month ago, and they completely kick ass. They have absolutely no grip, and their mud shedding ability is next to none - which has raised my riding skills, IMHO, to a whole new level.

I actually bought them without knowing a thing about tires (only that they were on sale), so it was mostly prayer to the bike gods that they'd fit. Hence the first question: can anyone tell me what all those numbers mean on the Price Point site, i.e. what's "2.1", "46mm casing diameter", "50mm max. tread width", "127 treads/in. casing"?

Also, now that I'm addicted to such tires, I was looking at something similar (is it?): the Ritchey Speedmax (http://www.rei.com/online/store/ProductDisplay?productId=83736&storeId=8000&catalogId=40000008000&langId=-1). Are they basically SS Revolts with hair? Also, in the aforementioned link, what do those numbers beside "Dimensions" stand for (does 26 in. = wheel diameter? What's 2.0 mean?)? Does weight really matter that much?

Lastly, I've always measured my tire pressure by squeezing them, but lately, I've read in many places warning how bad things can happen if I don't inflate them correctly, and how squeezing them is not a good way to measure the pressure. What's up with that? Is it just a marketing scheme to sell more fancy pumps made of some expensive metal with fifty gauges, or is there even a grain of truth to these dire warnings?

Alright. Thanks for reading. Please answer accordingly.

Originally posted by EpsilonArmati


Lastly, I've always measured my tire pressure by squeezing them, but lately, I've read in many places warning how bad things can happen if I don't inflate them correctly, and how squeezing them is not a good way to measure the pressure. What's up with that? Is it just a marketing scheme to sell more fancy pumps made of some expensive metal with fifty gauges, or is there even a grain of truth to these dire warnings?

Alright. Thanks for reading. Please answer accordingly.


It's really your personal choice. If you ride a heavy loaded tourer, and the tire is thin and narrow, it will have to be inflated probably over 80 psi pressure, but at 80 it will already be hard as a rock to the finger feel. So, if you keep pumping, you might accidently pump over 120, that might be the maximum allowed pressure for that particular tire. In such a case, I would use a gage to be on the safe side...
I think bicycle tire is not as important as let's say motorcycle or auto tire. Those creat a lot of heat and if over inflated 0 have big chances of blowing up...

If you visually don't notice too little air and the rim is not touching the ground through the tire... It should be fine

I have yet to see a pump with fifty guages on it, you can buy a floor pump with a consistent guage for thirty dollars. Worth it if only because you need to pump up your tires every couple of rides(Some road tires have to be topped off every day) When I compete I set my tires to the pound based on the type of terrrain, this is in trials where grip is a big deal.
About the only real problem with guessing on tire pressure is to go to high and damage the casing or blow the tire off the rim.

Regarding pumps:

Call me cheap, but I refuse to buy a $30 pump just because it has a nice gauge on it when a $5 WalMart pump works just as well (without the gauge). Is there anywhere I can find a tire pressure gauge? I've looked all over the 'net, but can't find one that's seperate from the pump (and car tire gauges aren't very useful).

Why aren't car gauges useful. I use one just fine. It is accurate to 2.5 pounds (you can guess for more accuracy in between lines) which is more than accurate enough for bike tires.

Here are some excellent pumps, both of which cost less then $20 and include a guage:

http://www.nashbar.com/profile.cfm?category=106&subcategory=1075&brand=&sku=2420&storetype=&estoreid=
http://www.nashbar.com/profile_moreimages.cfm?category=106&subcategory=1076&sku=6058&brand=

For me, using a guage is absolutely necessary because I ride different terrain often. I need to be able to get a good inflation for the type of riding I'll be doing.

Draft

Originally posted by Maelstrom
Why aren't car gauges useful. I use one just fine. It is accurate to 2.5 pounds (you can guess for more accuracy in between lines).

hummmm, every car tire gauge I've ever owned has lines for every 1 psi.

BTW the foot pump I bought from CDN Tire was $8 bucks without a guage, $13 with. Far cry from $30 bucks.

Originally posted by KrisA
hummmm, every car tire gauge I've ever owned has lines for every 1 psi.

BTW the foot pump I bought from CDN Tire was $8 bucks without a guage, $13 with. Far cry from $30 bucks.

Maybe that was $30 US? the dollar has surged of late. ;)

Where were you when I needed to buy a floor pump!! If I could have made off with a floor pump with a guage for $13, Id be a much happier, yet still cheap man!!

my handpump doesn't have a gauge, and my floorpump doesn't take presta... i use the "feel" technique where i get on my bike and see how much the tires compress... *shrug* not the best way but i try.

To answer your first question, tire sizes look like this: 26 x 2.1. The 26 is the wheel diameter (26 is the most common mtb size) and the 2.1 is the tread width. Most tread widths will fit on any size rim, but don't expect a 1.8 racing tire to fit on a DH rim too well. Also, if your tire is too wide it may rub on the fork arch or the seat tube of an XC bike. If you stay within the 1.9-2.1 range you'll be gravy.

Oh, and why waste your time with semi-slicks unless you do a lot of racing on dry, fast trails? You must be a glutton for punishment :D