Heated argument on our last group ride and I know this has been discussed to death in the past, but I could not find any updated threads on this. And it seems almost impossible to find relevant Crr data on (even newly launched) tubulars today.
On the excact same bike & wheelset, disc rear, 80mm front, at 40 kmh, how many watts or minutes over 180km would I be loosing, running the fastest tubulars today (say maybe a Vittoria Corsa G2.0 Speed, or Michelin Power competition) compared to the fastest tubeless (say Corsa Speed 2.0 or GP5000s) ?
Lets assume all tires in both categories are 25 mm
Heated argument on our last group ride and I know this has been discussed to death in the past, but I could not find any updated threads on this. And it seems almost impossible to find relevant Crr data on (even newly launched) tubulars today.
On the exact same bike & wheelset, disc rear, 80mm front, at 40 kmh, how many watts or minutes over 180km would I be loosing, running the fastest tubulars today (say maybe a Vittoria Corsa G2.0 Speed, or Michelin Power competition) compared to the fastest tubeless (say Corsa Speed 2.0 or GP5000s) ?
Lets assume all tires in both categories are 25 mm
The slowest possible tire is one that gets a flat.
Not only do tubeless tires have a couple better watts rolling resistance, they are also much less likely to flat.
Tubeless tires get better every single year. Five years ago they were a nightmare to install. I recently installed one in about five mins with a regular pump. I’d take that over nasty glue.
Agree it would be interesting to have updated data on the newest tubulars.
So lets say
180km, 205watts, .23 cda .00225 will give 39.95 call it 40km/h in 270.36minutes,
180km, 205watts, .23 cda .00282 will give 39.6km/h and 272.27minutes
We are close to 4.5 hour IM pace here, but yes about 2 min
Power measured at hub, so 211ish at crank
Flat course, no wind, 1.18 rho (need to put in all these caveats before the ST math/physics police pull me over)
BTW, not for you but those rolling their eyes going ya…whatever, set that CRR to something like .004 (which not so long ago was not so bad) and you are at 282 minutes, 12minutes slower.So if people don’t think tires and air pressure are a big thing…
Agree it would be interesting to have updated data on the newest tubulars.
So lets say
180km, 205watts, .23 cda .00225 will give 39.95 call it 40km/h in 270.36minutes,
180km, 205watts, .23 cda .00282 will give 39.6km/h and 272.27minutes
We are close to 4.5 hour IM pace here, but yes about 2 min
Power measured at hub, so 211ish at crank
Flat course, no wind, 1.18 rho (need to put in all these caveats before the ST math/physics police pull me over)
And of course once you factor in aero, that very likely also helps tubeless, as clincher-type tires almost always beat round tubulars. Case in point Ganna in his hour record (I’m assuming that the tires he rode were not the lowest possible rolling resistance).
Agree it would be interesting to have updated data on the newest tubulars.
So lets say
180km, 205watts, .23 cda .00225 will give 39.95 call it 40km/h in 270.36minutes,
180km, 205watts, .23 cda .00282 will give 39.6km/h and 272.27minutes
We are close to 4.5 hour IM pace here, but yes about 2 min
Power measured at hub, so 211ish at crank
Flat course, no wind, 1.18 rho (need to put in all these caveats before the ST math/physics police pull me over)
And of course once you factor in aero, that very likely also helps tubeless, as clincher-type tires almost always beat round tubulars. Case in point Ganna in his hour record (I’m assuming that the tires he rode were not the lowest possible rolling resistance).
That is a very good point
I think what you are saying is without any other change, the CDA in the tubeless setup may be .003 better, giving you another minute with those numbers.
Well actually if you make that argument the slowest possible is one that gets you DNF or DNS. I find that’s actually more likely with a tubeless than with any of the other options. Because when things go wrong on a tubeless they are really hard to fix on the go.
(Tyre doesn’t seat properly, doesn’t inflate, tyre stuck and too hard to take off).
I’m not saying it’s very likely, just more likely. And you’re not doing a lot of IM in a year so I’d rather lose a minute than risk DNF/DNS.
In my experience with tubeless I’ve seen tyres not seating/reinflating after travel and having to add way too much solution to believe it’s still better than any of the alternatives (good clincher with latex?). I do wonder how people deal with that (are they just lucky and I’m unlucky? Have I chosen inferior products? Have I not followed best practices?) and if the tests on tubeless aren’t made on ideal conditions and not real world conditions.
In fact a lot of the calculation is based on best case conditions.
In practice the calculation should take into account expected value weighed on the probability of various situations and your level of acceptance of unlikely but possible scenarios (things like couldn’t seat the tyre with your 2 co2 cartridges).
Respectfully speaking, your comment doesn’t really add to the conversation. I mean - what you’re saying was exactly my point. I know that when they work well they work. I know some people are very happy with tubeless whereas in my experience I’ve seen several issues that I’ve never had with good clinchers - even the tight ones. It makes me wonder what am I missing. Am I very unlucky, are they lucky? Are there ways to minimise the risk of those issues appearing (choice of product?) that I don’t know? And these things do happen, I’m not the only one (searching on google for “tubeless burping”, “stubborn tubeless”, “tubeless stuck” bring plenty of results which I’ve consulted when having to solve them).
So for me, a formula to see how much faster they are in a race scenario would need to take into account the probability of something going terribly wrong.
I have been riding tubeless since 2017 and have had 3 flats in 6 years. My bet is you are riding way to high of tire pressure, go look at enve or zipp chart and follow, I dont ride over 40-45 ever. Also to fix its cake, sealant in there seals the hole and you shot CO2 in and its fixed. If not u carry a plug kit, quick insert a plug in 30secs and co2 and your good.
There are plenty of clincher tire/rim combos that are abnormally tight as well. As for tubulars, you have to carry an entire spare tire that’s going to be a beast to swap out roadside, not to mention slower after roadside repair.
Tubeless v clincher roadside swap out has never been a significant time difference in my experience. Pop the bead off, take the valve stem out, throw a tube in, bead on, inflate. 5 minutes if you’re in a hurry.
If you actually want to make a ‘flat-adjusted’ formula for the fastest tire then you need a lot more data than the probability of something going wrong. Just as a baseline:
Expected race time=(Baseline time) - (tire wattage penalty) - - - (wattage penalty for carriage of flat repair kit)
The point being that for most non-tubular tires everything besides rolling resistance is a comparatively small overall value. If you are unable or unwilling to learn to change tubeless tires in a race situation then just use clinchers.
