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this post was submitted on 01 Aug 2025
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No experience with TPU.
They should only have significant effect during acceleration and deceleration. Once the wheel is spinning, whatever mass it is has stored the energy needed to spin it up so the mass doesn't affect the energy needed to keep it spinnig. Air drag tries to slow it down but that only acts on the outside of the tire which hasn't changed.
Acceleration takes a lot of energy and weight reduction in the wheels is very noticeable. I've no idea what the savings are in watts, but perhaps the energy saved during acceleration leaves more available for cruising? I don't know if you're saving enough for an extra 5-10kph at cruising speed, given that air drag grows exponentially. 5-10kph on top of 30kph is a lot, and on top of 40 - exponentially more.
Which leads me to the psychological boost. You're high on an upgrade and you push like a mf. We've all experienced the power boost you get evrery time you click the lever of a new high end shifter!
Probably a combination of those.
Post in time with reliability observations. How much top up they need in comparison to butyl, etc.
"Yet" 😁
I was thinking that at first, but then I went out and did it again, then again. Most of these efforts are definitely not pushing it at all... I'm able to sing while breaking personal bests, and this is all in the hoods, not trying to be fast!
But I'm sure there is some psychological push, too. It's hard to control for everything when riding in the real world.
I'll see if this can be sustained over the next several months. I do have a 30km loop that I've specifically planned for benchmarking, so that would be nice to test on.
Don't forget that you're also getting better at cycling. So there would be improvement over time even if you hadn't changed to tpu tubes.
Tires fitted with TPU tubes supposedly have measurably lower rolling resistance, something to do with how the tire and tube interact when the tire is deforming under compression
Huh, and that can reduce energy even while cruising then?
Yep
https://www.bicyclerollingresistance.com/specials/tpu-inner-tubes