Tire Pressure on Trainer

[Deleted User]

Total newbie question I’ve been thinking about...
How much does tire pressure matter on the trainer?  I’m riding a Kinetic Rocak and Roll “dumb”’trainer. Should I check/top off tire pressure every ride?  What’s a good target pressure (or approach to setting a target)?

Al Truscott

https://www.cycleops.com/post/blog-15-why-tire-pressure-matters-for-riding-inside

[Deleted User]

Thanks. I scanned that article but missed the key point!!

Derrek Sanks

Chris,

The article recommends 90-100 psi.
When tire pressure drops, you lose watts. If you're using virtual power or zpower on Zwift, then it's important to check tire pressure and keep it at the same psi every ride. This will give consistent virtual power readings. 

Shaughn Simmons

The model in the picture from the link provided by Al is exactly the model I am using. The Cycle Ops fluid trainer, low tech, cost effective and almost indestructible.   I usually inflate to ~100-105 PSI once a week....will prob check that more often now....

SS

Francis Picard

Also what I read somewhere is to ensure to rotate your front wheel so the pressure is not on the same point for all the winter months where we leave the bike on the trainer.

[Deleted User]

Thanks Francis. That makes a ton of sense and I wouldn’t have thought about that. 

Satish Punna

I used to have a rock n roll trainer.  If i didn't pump the tire up to 140psi it would get really hot and spew rubber bits on the wall behind me.  This wasn't an issue on the cycleops trainer I had previously, so maybe something peculiar to the design/clamping mechanism of the rock'n'roll.  I didn't use trainer tires, however, just an old GP4000s. 

[Deleted User]

Thanks @Satish Punna. I had the same issue before getting a trainer-specific tire!

Dave Tallo

I’m reading that cyclops article, and there’s a big ‘waiiiiit a second’ moment On the authors point re 10 watts from different tire pressure.   My powermeter is a Powertap hub, and it’s an independent strain gauge that’s telling me the force I’m exerting from my pedals to the chain to the cogs to the hub.    I just don’t see how tire pressure is affecting wattage here ... I would imagine that the PM is telling me power, and if I changed gears, or even rode with the brakes lightly applied, it would still accurately tell me power.   Also, I would guess that the same would be true from crank, B.B., or chainring-based PMs.     

Am I missing something?  

Shaughn Simmons

@Dave Tallo
I also run a PT hub G3 on my trainer bike.

Your observation is correct in as much you are riding based on power alone and not measuring trainer speed/distance.  If you are on Zwift, which uses your power to weight ratio, your current back wheel speed would make no difference and your comment would equally be accurate.

If you are accustomed to measuring your trainer speed as it is aligned with your power using the speed of the back wheel, this would be the only time the tire pressure would come into play.  A lower tire pressure requiring more watts to turn that back wheel at an equal speed would manifest.  Honestly, I have never paid any attention the my trainer speed for many reasons.

All that said, a properly inflated back tire on the trainer vs. under inflated, should require less watts to turn a 90 cadence (for example), so cadence is going to be impacted as well where a severely under inflated tire, will require more watts and more of a grind cadence in an extreme case.

For me, at the end of the day, I just want that back tire to be ~100 psi and be done with it knowing that regardless (and to your point) watts are watts.....

Al Truscott

Dave Tallo said:

Am I missing something?  

A watt is a watt no doubt, and if thats all you care about, then tire pressure means little until you pop a tube from a pinch flat. But if you are using something like trainer road or zwift, it becomes more complicated, as others like KMFm describe.

Dave Tallo

Got it. Fwiw, I've used the same orange conti trainer tire to train for 22 Ironmans ... 105 psi before every ride,  three turns of the Kurt Kinetic roller knob, and roll.

These two have been the most reliable and enduring pieces of gear I've ever owned.