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| The Blackborow DS on the way home from work Saturday. |
Sounds good, right? Well, that all depends on whether or not you hit on the "right" air pressure choice. Air pressure in fat bike tires probably makes more difference in how you ride, or even ride at all, than it does with any other type of bicycle.
For one thing, you have a massive tire with a lot of volume. This dictates a much lower pressure than you might use in a gravel bike, and extremely different than a road bike would use. Because a fat bike tire doesn't need a very high pressure to work correctly, a little air taken out or added in can make a big swing in handling and ride feel.
Then you have the way cold air can make your job setting air pressure a lot fussier. Cold air has the effect of lowering air pressure versus what you may have set in a heated garage or workshop. Because a little change in a fat bike tire can make a big difference in how the bike will ride and handle, as stated above, you should account for the change in air pressure cold air can cause. A good way to accomplish this is to set your fat bike air pressure after the bike has been out in ambient temperatures for at least 15 minutes.
I set my tires up at seven psi knowing this would drop a bit after being outdoors. (I didn't have time before work to set the bike outdoors). I took the gamble, and it worked great. The streets were 100% covered in soft snow at about three to four inches. Same thing when going back home with the exception that we had received another 4" while I was at work.
The Blackborow DS did really well. I will say the pump you choose to use makes all the difference in the world when dealing with low air pressure. I had been using seven or eight psi as it read on the dial of other pumps but this newer SILCA Terra pump has a lot more accurate low psi capability and it showed up for this ride. My feeling is that seven or eight on the other pumps is actually a bit higher than seven or eight psi on the Terra pump!
I'll have more to say about air pressure throughout the week, so stay tuned.....
I once did the basic math on temperature-related tire pressure changes, and figured out that for every 10 degree drop (relative to when the pressure was set) will result in approximately 1/2 psi reduction in pressure. It’s a formula that’s worked well for me, so while it may be imperfect, it’s the best I’ve got.
ReplyDelete@MG - That's great information! Thanks! I believe Bontrager had a similar chart showing the relationship between cold air and psi at one time, but I could be wrong about that.
DeleteExactly the same feeling I find with my plus tyres. They are much sensible to air preassure than the usual for me before: 2.2 or 2.4 mtb tyres. Now with the 2.6-3.0, the difference between 8-10 psi, to 12-14, is huge! I pressume that with your Singular you may find more or less the same circunstance?
ReplyDelete@Pedro - You are correct to assume that I have found these things to be true on the Singular with the 29 X 2.8" tires. I generally run from 16psi on softer terrain to up to 20psi for hard surfaced roads. Those 4psi make a wide range of characteristics possible to fit various terrain choices.
DeleteI've found the Bontrager tire pressure chart very useful for the fat biking I do in Edmonton. Our ambient temperatures can vary by more than 25 C over a couple days at times, so it that chart is very helpful guide in making adjustments before each ride
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