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CX Tire Pressure(7 posts)

CX Tire Pressurelexington476
Nov 30, 2003 3:03 PM
I cannot seem to find the correct tire pressure for my racing. The state championship is next Sunday (12-7). Today I did my warm up with ~55 PSI, felt that was to low; then put in 80 PSI for the race. Started the race and felt the tires were sinking/cutting into the grass. I then stopped and let some air out. However, I was never too well off this race, still seemed to be too slow. Maybe I am just slow. I used my MTB hardtail to race, with 26x1.3 Hichation Cross Comp tires. The course was pretty flat with one set of double barriers, and something like five sand pits. I ran most of the sand pits. The grass was somewhat damp/wet, not really muddy just wet. Therefore, people would sink in just a little bit. I finished 9 out of 9 in C-men. I did stop by the park that it will be at; it is much like today's race, flat.

For the next race, how can I find the right PSI for the course?
Videos and Pictures from that Racelexington476
Nov 30, 2003 3:23 PM
Take a look at the pictures and videos I took after my race. This is of the B and A races:

Click on Hudson Mills 11-30-03
Race TipsGripped
Dec 1, 2003 10:57 AM
After looking at the video from Hudson Mills ... I can't believe that not many riders shouldered their bikes for the sand runs. Even more amazing is that some riders actually pushed(!) their bikes through the sand. One of the videos shows a guy with a shouldered bike moving quite a bit faster than a couple other guys who are just lifting their bikes. For any longish runs, I think shouldering is much faster.

On another note, all the racing seems kind of flat. I lived in Ann Arbor for 18 years and I know that there are a lot of hills in that part of MI. I can't recall whether Hudson Mills has much in the way of hills but I know that there have to be some really good places for cross courses in SE MI.

I only miss Ann Arbor a little. Glad to be living in the Pac NW!
re: CX Tire Pressurehaystack
Dec 1, 2003 1:29 AM
I made the mistake of racing on too firm tires once too often. I've settled in this season at 40-50 psi depending on the course conditions. It usualy takes a few warm up laps for me to get it close, but I can tell if they're too hard as I'm bouncing all over the place. Now that's on my rigid CX bike. Your MTB may be different. Hard to believe, but you'll be faster on tires of lower pressure if conditions are sandy, muddy and maybe wet grass.
re: CX Tire PressureMShaw
Dec 1, 2003 11:23 AM
Practice. You want just enough pressure not to pinch your tires, but not so much that you cut right down through everything.

When you pre-ride the course, start out firm, let a bit of air out, try it some more, let a bit more air out, etc. I know for my 34c Tufos, I can't run much less than about 42-45 psi or I'll start hitting my rims too much.

Air pressure is so personal that making blanket recommendations over the internet is pretty useless. What works for me may be too little for you and vice versa. Best to ask some of the more experienced guys at the next race. Most crossers are willing to help the new guys...

re: CX Tire Pressureskinl19
Dec 1, 2003 2:15 PM
Doug, I was down around 42-45 on the cross tires, you could probably run that with no problems. Jeff Weinert talked me into running lower pressures a few races ago. This last race was completely diffent than past years' races at Hudson Mills. They kept us on the one side of the park and eliminated the long paved section and the last hill run-up. Lower Huron should have a few more hills but you'll be running them.
re: CX Tire Pressurelexington476
Dec 1, 2003 5:04 PM
Here is what I remember from the blur of this race:

9 out of 9

The weather for this race was nice, not very cold. Set my tires to 55 psi, did my warm up; felt it was too soft so I put in 80. Got to the start line with about one minute to spare. The course was very flat, not really hills, a few off camber turns, one set of double barriers, and some five sand pits. They went crazy with the sand pits. On the first lap the dude in front made a wrong turn and lead half the pack into the wheel pit, me among them. I knew about the turn since I did do one pre-ride lap, but stupid me I following the dude in front of me, that did not help for my placing. Once I started, I felt the tires were cutting into the somewhat wet grass and slowing me down too much. Therefore, I stopped and let some air out of the tires, even that did not seem to speed me up very much. I road and ran some of the sand pits, running seem to be that best, especially after a few laps and the pits being turned up by all of us. I had to swap my warm gloves for my light gloves, which I had with me. On the last part of my last lap I passed this one kid, then he comes burning past me on the home straight away. I try to catch him but do not. He then stops in the middle of the finish area, where I run into him at just about full speed. I hit his back wheel and knocked myself off my bike, rolling onto the ground and my back (I had on my camelbak). Next Sunday (12-7-03) is the state championship, I am going to get there for sure this time to calibrate the tire PSI to the right amount and find someone to hand me water bottles and not use the camelbak. Dad should also be there to watch, I hope some of the other friends also make it out to cheer me on.