TPU Inner Tubes (Race-Day)
Reference models: Tubolito S-Tubo, RideNow TPU, Pirelli SmarTube
CWPM vs Sustained bike power
Cost per minute saved across the full slider range, all other parameters held at your current profile.
FORMULA CWPM = cost ÷ Δt, where Δt = (min/h at your speed) × κ(slider) × Tbaseline(slider).
Curve linear-rolling sets the empirical κ bump; Tbaseline is the leg duration at your profile.
Time saved vs Sustained bike power
Minutes shaved at the 140.6 Full format as your slider value varies.
FORMULA Δt = (min/h at your speed) × κ(slider) × Tbaseline(slider).
Curve linear-rolling sets κ; Tbaseline is your 140.6 Full bike leg duration.
Time saved across race formats
Minutes shaved if you raced each distance at your current profile.
FORMULA For each format f: Δtf = (min/h at your speed) × κ(profile) × Tbaseline(f). Only the leg distance — and therefore Tbaseline — varies between bars; κ is held constant from your profile.
Cost vs time saved — bike alternatives
Every bike upgrade in the catalog plotted at your current profile. The line is the Pareto frontier: anything above it is dominated by a cheaper item that saves the same or more time.
HOW TO READ Each dot is one upgrade. Its horizontal position is the time it would save you at your current profile — the same Δt computed in the charts above. Its vertical position is the upgrade's cost. The green dashed line is the Pareto frontier: items where no cheaper alternative matches or beats them on time saved. Anything floating above the line is dominated — somewhere down-and-to-the-right sits a frontier item that delivers the same or more minutes for less money, so it's the better buy.
Why it works
Polyurethane tubes shave 40–60 g per wheel vs butyl and roll faster than latex while puncture-sealing better. A race-day swap, not a daily-trainer choice — long-term durability lags butyl by ~30%.
Rolling resistance — watts saved scale with $v^1$, so time benefit falls as $P^{-2/3}$: weaker riders gain proportionally more.
Source basis for the savings estimate
1 referenceThe ΔCrr = 0.000408 primitive is a calibrated
midpoint drawn from the literature below. Peer-reviewed studies are weighted most heavily;
independent / industry labs fill gaps where peer review is sparse for this gear category.
- Independent laboratory tests of bicycle tire and inner-tube rolling resistance.bicyclerollingresistance.com.De-facto standard Crr database for road, gravel and TT tires; controlled drum-roller methodology.bicyclerollingresistance.com
How the savings estimate was built
ΔCrr 0.000408Rolling-resistance benchmarks → ΔCrr → watts saved at your actual speed.
- Source steady-state Crr reductions from third-party rolling-resistance labs.
- Watts saved scale with speed: ΔP = ΔCrr·m·g·v at the rider's on-the-fly speed.
- Via ΔM/h = 20·ΔP/P the time benefit falls as P^(−2/3) — no empirical κ needed, the physics supplies it.
This is a calibrated model number, not a measurement of your equipment.
The value reflects published delta-ranges for the Foundations category
with a linear-rolling response, biased toward independent rather than manufacturer data.
The slider sweep above shows how watts-saved at your speed and the curve κ reshape it across athlete profiles.