[pmontra]

28 mm tires used to be huge tires. Pros didn't ride anything wider than 23 mm in the 90s. 25 mm would be for special occasions. 21 mm on tracks, sometimes even 19 mm.

I think than Valverde used a 28 mm in a Roubaix and at the end of the race said that it was too much and not worth of the extra weight and front section.

Every pro is riding on 30 or 32 mm now. Of course the rims are totally different and wrap those tires in a way that the old metallic rims could not do, hence the aerodynamic gains.

Edit: I've got a gravel bike with 42 mm tires and a 28 mm set. I use the 28 mm when going in the hills on asphalt. I'm with you on that: it's a day/night difference. On mixed mostly flat terrains the 42 mm tires are the best compromise.

[bennyelv]

Unfortunately you cannot discount the “sponsor effect” here. Wheel manufacturers have been pushing wider rims because it helps them sell another set of wheels to everyone.

In the days of rim brakes a wheel had a finite life (the length of time it took to wear down the braking surface). Then shimano and the frame builders pushed everyone to disc brakes, so the wheels now last for ever. What do you know, 2 years later all the wheel manufacturers are claiming “wide is better” and flogging everyone new wheels.

I’ve not seen any clear evidence that they’re right, and there’s lots of intuitive reasons to think that wider tyres will be slower (aerodynamics!). I remain sceptical, but genuinely hopeful that someone who thinks that wider is faster can provide me with some solid evidence…

[mariusor]

I feel that any marketing strategy that relies on the niche of a niche formed of the people that would buy the cutting edge cycling gear just because it's presented as an improvement over the status quo, would hardly bring any benefits to any wheel maker.

I am 100% sure that in this age of "marginal gains", the pro tour teams would not go for anything that doesn't give them it unless severely hamstrung by sponsorship deals. And I doubt that the wheel sponsors don't have multiple sizes available.

And I think you're severely overestimating wheel life span for modern models, at least due to the fact that carbon is more brittle than more pedestrian materials. Just look for Pogacar's fall earlier last week in the Giro to see how a simple flat tire makes the whole wheel a risk.

[bennyelv]

>And I think you're severely overestimating wheel life span for modern models, at least due to the fact that carbon is more brittle than more pedestrian materials. Just look for Pogacar's fall earlier last week in the Giro to see how a simple flat tire makes the whole wheel a risk.

My experience is personal, but I get 50,000km out of a set of rim brake carbon wheels ridden in all terrains and conditions and through northern european winters. At that point you're also starting to lose spokes/nipples to corrosion, but the rim could be rebuilt with new spokes and a new hub if it didn't need a brake track. That riding includes racing, crashing, potholes, punctures.

Pogacar rides on Enve wheels, which are now hookless and therefore a puncture is much more likely to result in damage. Another innovation that makes life worse for the consumer and better for the manufacturer.

[303uru]

You're kidding yourself if you think Pogacar would run 30mm tires at 55 PSI at the detriment of speed to please his sponsors. Cyclists are notorious for re-badging stuff they don't want to use and being super finicky with their gear. You're talking about guys that hardly celebrate a win with a $250k purse because they want to make sure they stopped their ride right on the finish line on their headunit.

[bennyelv]

I don't share your optimism about the strength of the scientific method in pro-cycling :) It's not too long ago (admittedly in the pre-disc brake era) that climbers would have their bike built up to sub 6.8kg and then add weight to it to bring it up to the limit rather than use deeper wheels.

If you look at TT equipment all team members use the same helmet regardless of the fact that helmet performance varies massively from rider to rider.

The 2016 S-works Venge is 5w faster than both the SL7 and SL8, so on flat stages all specialized sponsored teams are riding it... aren't they?

Why is nobody wearing a TT Helmet and visor on a normal road stage?

[seadan83]

> Why is nobody wearing a TT Helmet and visor on a normal road stage?

(1) weight is not always worth it, notably when there are lots of climbs

(2) riding with others, need to be able to turn your head. Further, you can't get as super low when in a big group. It also doesn't help as much because the group dynamic is more important than crouching extra low and/or helmet drag

(3) out of the saddle sprints.

[bennyelv]

Definitely not every road stage, but on a flat stage if your aim was to break away and stay away you should absolutely do surely?

Nobody ever has…

[seadan83]

To break away requires you to put out 30% more power than the person behind you, and then also means you need to put out 30% more power than the rest of the field. That is a good recipe to go out hard, overcook, and then get passed up by the entire peloton.

The 30% - Drafting is good for a 30% power increase. When in the middle if a peloton, even more. The breakaway plan can make sense, but not by fooling around in a TT helmet in the middle of a peloton for a few hours first.

[tpm]

> Why is nobody wearing a TT Helmet and visor on a normal road stage?

Because it doesn't work as much alone as in combination with specific aero body position. But you can't be in that position in a normal road stage because the aero handlebar extensions are forbidden in mass start stages.

Also there are less aero benefits to be had when you ride in the peloton behind other riders.

[seadan83]

You don't need aero bars to have you arms forward and narrow. It's not particularly safe, but doable for a while.

The aero bar question (whether to have them or not) comes down to how long you will spend drafting and climbing. It's a more interesting decisions in Olympics and triathlons than most road bike racing (the latter it makes no sense because people are drafting as much as possible).

[tpm]

Arms forward and narrow, forearms on handlebar is a banned position of course :)

https://www.cyclingweekly.com/news/racing/uci-publishes-imag...

[seadan83]

As for evidence, here you go: https://www.renehersecycles.com/why-wider-tires-are-not-slow...

The aero drag of wider tire is not a lot. It is more the wider tires are not slower. Wider tires allow: more air volume in tire, lower PSI. In turn those help ride quality.

[bennyelv]

The aero drag is the elephant in the room here. By this study’s measurements there wasn’t much difference, but what was the width of the rim they used with the narrow tyre?

A narrow tyre on a wide rim is a wide tyre. They don’t explain or address this issue. I suspect they would have used a wide rim with all the tyres, which is notionally a sensible thing to do, but in reality it’s completely flawed.

What are the results if you used a narrower rim with the narrower tyre so that the frontal area was actually reduced as much as it could have been?

[seadan83]

Rene herse has been doing those tests since 2006 "back when go-fast tires were 23mm." They covered a lot of variety and their conclusion is the aerial drag is tiny and real world conditions are more important than the idealized condition of tests on a steel drum.

The tests in the reference were done with a 21mm inner rim width. I believe that is neither super wide nor narrow. Arguably a good test bed rim to isolate the difference in tire.

Though, wide rim equates to a wide tire I do not think is true (at least, unsupported). The deep dish rims are only aero if the width is close to that of the tire. Reducing the ratio of tire width to rim width is aero! If anything, a wider deep rim on a skinny tire is increasing are dynamics. The aero dynamics of a wheel is not just a function of the tire alone. A deeper dish of more equal width to the tire helps that teardrop shape you want for aerodynamics.

My knowledge of tire/rim ratio comes from conversations primarily. References for that ratio being important are not hard to come by, eg: https://silca.cc/blogs/silca/part-5-tire-pressure-and-aerody...

The reference does go into some more detail why wide rim is desirable to reduce drag. I won't paraphrase further here other than to conclude a wider rim would actually be favorable for the skinny tire.Regardless, a middle of the road rim width was used in that data sample.

[alephxyz]

> Wheel manufacturers have been pushing wider rims because it helps them sell another set of wheels to everyone.

I think the push to wider tires and lower pressures on road setups is actually because hookless carbon rims are much easier to manufacture than clinchers, and hookless tires can't handle 80+ psi.

Clincher carbon wheels are basically considered a niche product by big manufacturers

[bennyelv]

You could be right about that. Hookless is an awful idea that benefits nobody...

[pandaman]

I think you might be transposing the cause and effect. Mechanical rim brakes had been limiting the wheel width because of physics of leverage, disc brakes opened demand for wheels of any width and users naturally migrated to the wider wheels.

[bennyelv]

It can't work like that in the world of mass produced equipment. You can only buy what the manufacturers are making, and as far as I'm aware there haven't been any wheels that are offered in different widths that the consumer can choose from.

It's always: this is the latest model, it has these features, thanks.

[pandaman]

I don't think this is a realistic world picture: if this was true then the wheel manufacturers would just keep making rim brake wheels, which a apparently more profitable in your view. In real world a wheel supplier will make wheels for the specs their customers, bike manufacturers and bike shops, order. And those order what their customers, cyclists, demand.

[bennyelv]

I hear what you're saying and that would normally make sense, but there are reasons why I don't think its true in the bike industry. It comes down to the same arguments that you often see on HN about whether or not a free market works.

Shimano can decide to stop manufacturing rim brake groupsets and spares for existing rim brake groupsets unilaterally. It doesn't matter if the customer wants it or not. The rest of the bike industry supply side won't object to it, because it pushes people towards replacing whole bicycles which benefits all of them.

Other component manufacturers can play the same games in the areas that they can control. Wheel manufacturers can start pushing to wider rims, and then increasing profitability with hookless. Benefits the frame manufacturer (oh no, you need a frame with more clearance!), the tyre manufacturer, doesn't negatively affect any other the other players who aren't directly affected, spin a marketing story about how great this new thing is based on dubious test results and claims, and off it goes.

Repeat that cycle a few times in a few different areas and you have the situation we are now currently in:

The price of a mid/high end bike has doubled in the last 5 years. The bikes have got heavier and more complicated and harder to maintain. The consumers are all pissed off with it and start leaving the sport. Sales suddenly fall off a cliff.

I'm not saying this as a conspiracy theory nut, but rather that there are a set of dynamics at play in this industry that mean that this kind of thing can happen.

[seadan83]

If shimano stopped making rim brakes, no tour de France athlete would use shimano groupsets. Rim brakes are lighter, that is why.

Would shimano ever give that up? No. All these companies pride themselves for being what the elites run. Dura ace would become a joke if no elites used it. The dura ace groupo upgrade is thousands of dollars (2k to be exact, it's the most expensive 100g you can pay for), & dura ace is high profi. So mo, too much brand risk. I mean, why haven't they stopped selling rim brakes already? It makes zero sense for shimano to do that.

Further, there are plenty of bike tire manufacturers making a variety of rim sizes. Some bikes can only do 25s max, makes no sense to only have a 28mm rim.

What's more, there's millions, probably hundreds of millions of older bikes that all need new rims every few years. For what you're saying to be accurate, no company would seize that demand and instead some sort of duopoly would instead opt for forced obsolescence. I don't see that as being the case (it is for thing like iPhones/cell phones, but the bike industry is very different)

[wiredfool]

I bet if you ran the same tires in 42 and 28, you'd be basically at the same speed, at least on smooth roads.

[pmontra]

The 28 wheel feels immediately faster. It's lighter, so it accelerates faster than the 42 one and there are a lot of accelerations from low speed in a ride, especially for slow riders like me. On the other side the 42 wheel should be better at keeping the speed because of the higher mass and inertia. Unfortunately that's wasted each time I use the brakes or I slow down.

[wiredfool]

Are your 28 and 42 tires the same type (e.g., the Rene Herse standard tires are the same construction across the entire size lineup), or is the 28 a road tire and the 42 a gravel tire?

I've got a road bike and a gravel bike. A while ago, I did the same workout, 12 reps of a local hill, 2.5 hours or so, once on each bike, separated by a week.

The road bike is 8kg and 25mm tires, the gravel is 12kg and 650bx42 or 48 tires. (might have been either, as I switched tires around then). The difference in time was 6 seconds.

The gravel bike doesn't feel as fast. It doesn't reward spinning, and the gearing jumps are just a little big for me (1x11). The road bike beats me up with vibrations, but it feels better climbing and standing. It's got closer gear ratios, so it's just a bit better matching. Now, to be fair, the gravel bike is running far better tires, so there's less resistance there. (and, that's basically why I bought it) But overall, they are basically the same speed, even on a hilly climbing workout.

[seadan83]

Narrow will feel faster, and lighter accelerates faster - but the perception is often over perceived.

So, the weight difference of 28 vs 42 is going to be 100g maybe. It's not a lot. Weight vs aero experiments have found conclusions like weight over 100 miles is tiny small compared to any aero gains (talking like +3 lbs having a few minute difference over hours). Which is to say, the effects you describe are pretty small when measured.

Moreover, the choice of 28 vs 42 is rare, feels like is more choosing 25, 28 or 32; or choosing something in low 30s compared to 40s. Meaning, the weight delta is even less in real world choices. What's more, you can go to 650b and have the exact same tire weights with much bigger widths.

[ActorNightly]

You cant really pump up 42c tires to 100 psi safely, so no.

Remember that the wider tires are more efficient at lower pressures than narrower tires. However as the pressures go up, the difference becomes smaller. Even without aero gains, the narrower tire will be faster provided its a smooth surface.