Register | Login
Attackpoint - performance and training tools for orienteering athletes

Discussion: Nice bike

in: Bash; Bash > 2017-05-06

May 8, 2017 5:01 PM # 
Mr Wonderful:
Looks like a happy place to spend many hours!
May 8, 2017 8:52 PM # 
Carbon's Offset:
I think the 29 inch wheels will be the bigger advantage on race day. When I raced 24 Hours of Adrenaline, I was side-by-side with someone on a 29er and I was on a very high end 26er and quite fit, but could tell he wasn't pedalling as hard to keep the pace.
May 8, 2017 8:55 PM # 
Carbon's Offset:
And play with those lower tire pressures. Schwalbe published a study that showed that lower tire pressures are faster because they roll over things easier (the only time it was less efficient was on pavement, and not by much. As soon as you are even on gravel or grass, the lower pressure tire rolls easier. And the lower pressure tire will have better grip and comfort: win-win-win!
For a recommended tire pressure in PSI, try: your weight in pounds, divided by 7. Then subtract 2 psi on the front and add 1 psi on the rear.
May 9, 2017 4:40 AM # 
Thanks for the tips. Wow, that is a low tire pressure - 17 and 20? Huh!

Last year at Storm was the first time I really felt like my 26er was a disadvantage. I would pass people in the technical ATV trails, then they'd roll by me on the road and they wouldn't even look like they were trying!

The only reason I've been feeling cautious about Storm is that I've ridden the Pivot so little and my instincts aren't always correct about how it will respond. I feel better after today although I still don't know what it will do on a slippery rock or in a big mud puddle, both of which I'll see around Warsaw. Anyway, assuming the brake problem can be solved, I think I'll try it! :)
May 9, 2017 4:54 AM # 
Carbon's Offset:
Yes, those pressures sound about right. I run about 18 or 19 in the front and about 21 in the rear, or I will sometimes go even lower on both, especially if it is wet and slippery and I want more traction. I love low tire pressure on the front for confident grip. You can even try lower. Because there is no tube to pinch, your only limits on lower pressures are:
- having the tire compress over sharp edges to the point that your pretty rim actually smacks against the rock ( one racer girl I have heard of runs her tires at super low pressure and says it isn't the end of the world if you occasionally feel your rims bottom out (even with Carbon rims), in fact that is how she decides her pressure is properly low enough!;
- the bead pulls off the rim or burps when cornering; or
- the handling feels too squirmy if the sidewalls aren't stiff and the tire can squirm when there isn't enough pressure to hold the sidewall in shape.
May 9, 2017 4:55 AM # 
Carbon's Offset:
Try those pressure on off road surface and see if they are any slower.
May 9, 2017 5:10 AM # 
Thank you - will do!
May 9, 2017 10:28 AM # 
Woah, never considered such low pressures (not that I ride very often). What if your 29er does have tubes to pinch? I guess I could try it and find out...
May 9, 2017 10:33 AM # 
I ran my winter Plus tires at 13-14 psi.
Summer ones are in the very low 20s unless it's really sloppy then I'll go lower.
I may run a bit higher at Storm due to the road sections.
May 9, 2017 11:54 AM # 
I run pressures in this ballpark with tubes, except the fattie which I ran at 5psi in snow and 7psi in wet dirt.
May 9, 2017 3:39 PM # 
Carbon's Offset:
On my first 29er, I followed this rule of thumb for tire pressures, but hadn't thought of the fact that my wheels still had tubes in them. So, I unintentionally tested that concern. I didn't have any issues with flats, and the bike handled well. That said, I believe this formula is intended for tubeless.

This discussion thread is closed.