Sprinting on tubeless
 

The Enve 3.4 AR Disc wheels look very tempting; smoother ride and faster. One question I have is about how lower pressure wheels perform when sprinting. I don’t want any softness or spring in my wheels when sprinting. I would be interested in hearing from anyone who has ridden tubeless and can report their experience.

I’m 190 lbs and run 28c GP5k’s at 75 psi on a 21mm wide (internal) rim. I feel no “spring” when I sprint. I think the wider rim bed helps with that substantially.

I have the Zipp 303S - 23mm int, hookless - with 28mm Pro One Addix @+/-60psi. I guess that I can't say that you'll feel zero spring, but I can say that nothing sketchy or untoward has called attention to itself. A quick search says you'd have another 20psi to play with on the Enve, which seems to have a max of 80psi (Zipp states a max recommended in the low 70s for my 303S, but I haven't felt the need). I'm at 185-ish lbs and can put a fair amount of torque on the pedals.

4.5 ARs at 65 to 70 psi, sprinting feels like it did on tubes.

I've been running tubulars at around 70psi, and get some squish- mostly noticeable with out-of-saddle climbing.

Figure it's a worthwhile trade off overall.

If you don't like what you get, a few more pump strokes will fix it.

For $3000, carbon wheels should come with di2 pressure control systems. Dial in some pressure in the rear tire when climbing, both if sprinting.

I will say that the “squish” matters a LOT less on race tires than reinforced tires. It’s enough to subtly alter your form with the latter - not good.

FWIW despite believing all the claims of softer is faster, I pump my tires a bit harder than normal for races or spirited rides. Wider tires will not stop you from running them hard. You’ll just be carrying a small amount of extra rotational weight that isn’t helping you besides maybe providing grip.

You've got to get down below 30psi before it gets sketchy. At 40psi it can be bouncy - like when you take your MTB/CX/Gravel bike out for the first time after being on the trainer. It's really no big deal on a road bike at 60psi.

At lower PSI, you do have more sidewall travel though. This is good and bad. When you lose traction on 23c/100psi because you're over the bar giving it the business, the rear will hop as it unloads, skip, instead of spin ( think we've all done this pulling away from a stoplight). Yes, this is traction loss, not something you did pedaling to lift the back end or that you tipped your weight over the front end (though these are factors) - high power cars with independent rear suspensions do this and performance cars with live axles do this under braking. With the lower tire pressure, the rear tire has got more choices other than grip or skip as it can deflect more, so it's less sketchy as long as the front isn't bouncing around.

Running 25mm Schwalbes at 85-90 psi; I'm around 175lbs. My sprints are in club rides - the typical county line type of sprint. But back in the tubed 23mm 110 psi days, I had issues controlling the side-to-side skipping around. I was glad to see the above video - because I always attributed it to bad form. I still think it's bad form, but it's nice to see a pro do it. My max 3 second power is 1440 watts - so, far from pro stuff.

On the 25mm tubeless, I never feel any squish or squirm and I don't get as much skipping around.

That's on the Champs Elysee, and specifically on the right side of the Champs Elysee, which is well known for being exceptionally bumpy and not a very good line.

He took a risk going that way and it didn't pay off. I don't think there's much he could have done with tire pressure to alleviate that particular part of the road when you're going 38+.