Low Tire Pressure

John Withrow

If you want to get in touch with your inner nerd, here's an interesting podcast on tire pressure...

Simple Summary: Use the best most supple and widest tires that will fit in your frame, then run them at pressures that are a lot lower than you'd expect...  

Might go against some of the conventional wisdoms.

http://cyclingtips.com/2016/08/cyclingtips-podcast-episode-9-rethinking-road-bike-tire-sizes-and-pressures/

 

Coach Rich

My Calfee road bike has disc brakes and the tire and available traction is what limits my ability to brake. That is, the disc brakes have sooo much braking power that I need to run bigger tires at lower pressures so I can begin to brake as much as the brakes will allow me to. So I've been running 28s at about 60-65psi. Very nice ride, tons of traction available for cornering and braking. 

On the Ventum I'm running the same Vitorria's and latex tubes that I raced with at IMLP. I ran them at 100psi this weekend for my long rides. Yesterday I made a fast, tight right hander at speed and felt the rear wheel drift a few inches. Fun stuff! 

 

John Withrow

@Rich-- You should actually listen to the podcast... Interesting stuff. They're saying that the ~65psi is also likely "faster" or "as Fast" as tires at 100-110psi (even though it won't "feel" faster). Would be interesting to do one of your normal routes on the Ventum with 100psi at a constant Power, then do the same ride with 65psi in the same position and same AP and simply look at the average speed of the two. Not perfectly scientific, but might be eye opening if it doesn't match "my" conventional wisdom. FWIW, I have always raced at ~110psi and I'm ~180-185lbs race day weight.

My question still on going very low on the psi is how low is too low for cornering (tire roll) or pinch flats or breaking your rim if you hit a pothole (they mentioned this early on in the podcast).

Coach Rich

Posted By John Withrow on 22 Aug 2016 03:58 PM


@Rich-- You should actually listen to the podcast... Interesting stuff. They're saying that the ~65psi is also likely "faster" or "as Fast" as tires at 100-110psi (even though it won't "feel" faster). Would be interesting to do one of your normal routes on the Ventum with 100psi at a constant Power, then do the same ride with 65psi in the same position and same AP and simply look at the average speed of the two. Not perfectly scientific, but might be eye opening if it doesn't match "my" conventional wisdom. FWIW, I have always raced at ~110psi and I'm ~180-185lbs race day weight.



My question still on going very low on the psi is how low is too low for cornering (tire roll) or pinch flats or breaking your rim if you hit a pothole (they mentioned this early on in the podcast).

Tire roll: my intuition is that a bicycle tire is going to slide out from under you before it rolls off the bead, unless we're talking crazy, crazy low PSI. Like I said, 60-65psi on the road bike is perfect and, most importantly, allows me to use more of the braking potential of the disk brakes. 

PSI test: I'd rather listen to a podcast / look at a chart vs doing my own test . And learning how to bunny hop is a great tool for saving rims 

Rich Stanbaugh

@John - depending on the the road surface, I ride down to 85/85psi - the worse the surface (Wisconsin) the lower I go. The theory being that this is faster because it forms a kind of "suspension" on the rougher roads. I've read that the primary change in technology that is making this possible is the newer tire materials making the sidewalls stiffer. Thanks for the link - will listen to the podcast tonight.

robin sarner

yes I worry about the pinch flats.   and damage to wheel rim.     the only time in an IM I got a flat was running 100 psi in the rear for 180 lb me.          versus back up to 110/105 now.        scared to go lower.

Clark Mitchell

On my "road" bike, I've been running 32s setup tubeless with 60 psi in the front and 75 in the rear. They are nice and plush with no noticeable rolling resistance penalty. I'm super happy with the setup, to the point of thinking about going tubeless on my tri bike.

JeremyBehler

Posted By John Withrow on 22 Aug 2016 03:22 PM

If you want to get in touch with your inner nerd, here's an interesting podcast on tire pressure...

Simple Summary: Use the best most supple and widest tires that will fit in your frame, then run them at pressures that are a lot lower than you'd expect...  

Might go against some of the conventional wisdoms.

http://cyclingtips.com/2016/08/cyclingtips-podcast-episode-9-rethinking-road-bike-tire-sizes-and-pressures/

 

I've read some of these stories and am intrigued as well.  I'm going to start testing different approaches.   I just got a set of Enve 7.8s and gotta say their strong warranty makes the fear of wheel damage essentially disappear.

Edwin Croucher

I am always on the lighter side. Will have to see how things are under 100.

Tom Glynn

Very interesting podcast! I had read a bit on this topic before, but talked about tire pressures were usually around 100 psi. With my tri bike, I'm running a 23 in the front and 25 in the back. Both around 110 psi. I'm pretty reluctant to drop them to 80 psi or lower, but will experiment dropping them to 100 or so to get some feedback.

For my road bike, I've got 23s front and back with 115 psi or so. Just habit. I also use Gatorskins for puncture resistance. Although they didn't mention names in the podcast, I'm pretty sure they were telling you not to use this brand, but rather to go wider and less pressure to make the tires more puncture resistant. The really stiff design of the Gatorskins sounded like they didn't respond well to lower pressure from what I inferred from a couple of comments.

Also a thumbs up to latex tubes in both road and tri from what I could infer. On my next tire purchase, I'm going to going wider.

Rich Stanbaugh

Here is a link to the Frank Berto article that is referenced in the PodCast... it has some decent guidelines for determining tire pressure.

Dino Sarti

I ride 23mm 100psi on all my bikes except MTB. My real fear is rolling the front tire off the rim in a high speed corner. I have seen it happen to pro's before, albeit running tubies, but it looks terrifying..... I will take a few punches to my taint versus high speed tire roll. Irrational fear, I guess, but I am afraid of sharks too....