[ActorNightly]

> something softer can absorb more of the little bumps (and also perhaps not fatigue the rider as much from a bumpy ride).

Not quite. You can air down narrower road tires for this. The difference is that a wider tire (i.e a tire with more volume) is going to be more efficient at lower psi, because of a wider contact patch that ends up spreading the load out more and deflecting the tread less.

This effect definitely is pronounced for gravel riding when you have to run pressures lower than 60 psi, and a wider tire is better. However for on road riding, even on rough roads, a narrower tire is going to usually be better, because you gain the aerodynamic advantage, even if you run at lower psi. If you can sustain above 20 mph, running a 28c tire vs a 38c will save you 20 watts, which is noticeable.

>Then bytul vs latex vs tpu tubes.

This matters extremely little for most people. Maybe like 4 watts at most. For racing, when you are optimizing everything, its worth it, but generally tubes matter way less then tire selection. That being said, there really isn't any reason not to run TPU tubes because they are a lot more pliable and puncture resistant.

Generally asking bike industry to do actual engineering is an impossible task, but for optimal design there is no reason why even road bikes should not have suspension that doesn't rely on tire compliance. You can do carbon leaf springs with very small dampers. The best we get is suspension stems and seatposts, which suck because you still have all that unsprung mass of the entire bike bouncing around.

[scott_w]

> a narrower tire is going to usually be better, because you gain the aerodynamic advantage

Testing has shown this to not be true. Width is less important than overall shape of the tyre/wheel/bicycle interface when it comes to aerodynamics.

[ActorNightly]

Then everyone in the peloton for races like Paris Roubaix would be on 38c gravel tires. The reason they run 28c is because while it sucks for cobblestone, there sre flatter sections where the aero advantage is worth it.

Per 10mm tire width increase, you are getting 10 watts more aero drag at 25 mph.

[seadan83]

Elite riders and teams are very conservative. They shift to new tech after it has been proven over decades.

Consider that from a programming perspective, imagine using no tech newer than 2004.

The transition to 28s took a long time itself

> Per 10mm tire width increase, you are getting 10 watts more aero drag at 25 mph.

Interseting, where can I read more about this? I don't think this conclusion lines up with either the article, or the research from rene herse. Travel surfaced also matters quite a it, I could see that maybe being true in an idealized setting.

There is more to it. Tire needs to be in contact with ground to transfer power. A skinny high PSI tire will spend a lot of time bouncing. Just one example of how other real world factors can be more significant.

[scott_w]

Gravel tyres have higher rolling resistance. Also, beyond 32mm, you start risking cornering ability on the road as there’s more tyre to roll over to change direction.

Aero drag is just not that simple. You can’t, without testing, make the claim you’re making. Also, you can’t make the claim outside of the exact setup you tested. A different rider, wheels or bike could test faster on 40mm because aerodynamic drag is that difficult to predict.

[wiredfool]

Van der Pol won on 32mm tires this year, vs his normal 28mm.

32 also happens to be the biggest tire that fits in his Canyon race bike.

[ActorNightly]

You are right, this year 32c seems to be the most common. I remember 2023 was still 28c, and there were tests done that I remember seeing where 28c was slightly more efficient than 30c, but at a higher pressure.

[bluecalm]

I feel the same about suspension but maybe it's just very hard to design. It would need to be very light and aero to make it worth it for road bikes which are pretty great on roads as they are. For gravel there is the Lauf suspension thing and the new light/short suspension forks but I am not surprised they are not very popular as a suspension fork means regular expensive maintenance. Why not just slap 2+ inch MTB tires on the bike instead?

[seadan83]

You may want to look into dropper seat posts. They have road versions that are relatively stiff.

Suspension weighs like 2 lbs (_very_ heavy) and can fail/needs maintenance, and for small bumps the shock absorber moving around loses a lot of power transfer. Nicer suspensions have lock outs so you can disable the suspension on roads and flip it back on when you're back in the mountains.

Fir road only, I don't think suspension ever would make sense. Fatter tires and a (for road) dropper seat post will likely give you all the suspension you need with little penalty

[ActorNightly]

Yep, for the front you can use something like lauf, which can be made more aerodynamic with smaller travel for road application.

For the rear same idea, make the seat stay and chainstay meet earlier and mount the axle mounting dropouts on carbon leaf springs in the same way.

You can also add a cable tensioning system to both suspension, which can be used as a lockout to make the bike more efficient.

[latchkey]

Lauf owner here (with the weirdo front fork). Absolutely love it!