Pro Cycling 2021

[Cid]

This is just fantastic racing.

 

[Cid]

Hatch: 'Well you have to feel for Moscon in the meantime'

How about no.

 

[hash tag]

Kharma

 

[Cid]

Colbrelli seems happy.

 

[beesonthewhatnow]

Just… wow. What a race, what a finish.

 

[beesonthewhatnow]

Colbrelli has had quite the season, hasn’t he?

 

[hash tag]

Fantastic.
Thanks for a great weekends racing/entertainment. The best weekend this year.

 

[twistedAM]

Well that was entertainment. So many mechanicals so it's also a lottery in some respects.
I wonder if we'll get a wet Lombardia on Saturday. Hope not.

 

[David Clapson]

An interesting test for disc brakes - Magnus said that the pads don't last long in muddy condtions, hence the guy who put his foot on the back wheel to slow down. What do you experts make of that? Sounded ridiculous to me...how can new pads wear out in 150kms?

And another thing, why no shallow rims today? Weren't lots of them breaking the 105% rule? Or were there lots of fat rims?

 

[twistedAM]

In other news, Greipel had his last race today. Cav spoilt the party.

 

[Cid]

An interesting test for disc brakes - Magnus said that the pads don't last long in muddy condtions, hence the guy who put his foot on the back wheel to slow down. What do you experts make of that? Sounded ridiculous to me...how can new pads wear out in 150kms?

And another thing, why no shallow rims today? Weren't lots of them breaking the 105% rule? Or were there lots of fat rims?

Hmm... Sounds odd. Certainly wet/muddy conditions will wear them faster, but not that fast. Three broad types; organic, semi-metallic and sintered. Organic is mostly an advanced rubber type thing, I think with silica... Then progressively add metal as you go up the scale. Organic will give you more bite, and are quieter, but wear faster and can be more vulnerable to contamination in muddy conditions. Various trade-offs as you change compounds... How fast any individual rider will wear pads is just hard to know; weight, how much they brake, conditions, compound etc etc. Mountain bikes (particularly DH) can wear through them pretty quickly, but then there's also a lot more braking involved. Honestly though I'd guess they're riding semi-metallics, and I'd be pretty annoyed to get less than 1,000 miles out of a decent set. I think I get a fair bit more out of mine (have not been tracking properly) and I am far heavier than any pro rider, presumably brake a fair bit more (and drag on the brakes), and don't have a mechanic to get them perfectly set up.

One thing is that you kind of want to keep the same pads with the same rotor as they'll perform better. So it's maybe possible that they'd get used for too long, but seems pretty unlikely in a pro team context, where the mechanic is obviously checking them pre race. But really just hard to say without knowing more about what they're using.

 

[beesonthewhatnow]

And another thing, why no shallow rims today? Weren't lots of them breaking the 105% rule? Or were there lots of fat rims?

???

 

[David Clapson]

To get an aero benefit from deep rims, their width needs to be at least 5% greater than the tyre. Otherwise the airflow over the rim is a disturbed mess, and the deep section of the rim is pointless, just a few hundred grams of dead weight. So say the boffins with the wind tunnels. This is the seminal paper on the subject: PART 5: TIRE PRESSURE AND AERODYNAMICS

Because of the cobbles today, all the riders used 28mm tyres, or wider. On normal roads they wouldn't use anything wider than 25mm.

So, the 105 rule says that anyone using deep rims today should have got some which were at least 29mm wide. I don't think anyone did...I'm fairly sure that nobody even makes a good quality deep section rim that wide. Everyone was using their usual rims, which are typically 26mm wide. To my mind that was silly - they'd have been better off with shallow rims which are lighter.

According to someone on another forum, I got it wrong, because even when you don't obey the 105 rule you still get some aero benefit from deep section rims, especially in side winds, which there were a lot of today. Plus, today's race was flat, so a couple of hundred grams of unneccessary weight on each wheel is neither here nor there.

I suspect another factor is that the sponsors wanted their sexiest wheels promoted, and they are typically quite deep, 45 or 55 mm. They're all the rage. All the punters are lusting after deep section carbon wheels...they cost a fortune. Fantastic business for the bike trade.

 

[hash tag]

I am perhaps going a step to far now, but does this actually give you a real and noticeable advantage, is it a noticeable and measurable marginal gain?

 

[David Clapson]

Yes, a substantial gain, not a marginal one. People have been getting pretty huge speed increases from aero wheels for years, but with narrow tyres, typically 19mm. What's changed recently is that people are using wider tyres, and aero wheels haven't quite kept up. They're getting wider, but progress is slow.

 

[David Clapson]

.

 

[hash tag]

Thinking back, I remember the huge difference between factory wheels and hand made ones, which were a joy.

 

[David Clapson]

Factory wheels have improved a lot. Hand made are still popular. Factory wheels are sometimes difficult to maintain at home.

 

[Ted Striker]

Gutted to have called it exactly as it turned out, as soon as Mscon went down and was in view up the road.

MVDP had to distance Colbrelli, - it was madness taking him to the velodrome, especially as exactly this scenario (with the same people!) played out exactly in the Euro Road Race a few weeks back!

MVDP and WVA seem to be human-powered derny riders for the peloton, especially if there's any chasing required, which really irks me!

Ignoring the physical wtf-ness of the Cobbles aside though, how good were the breaks/splits/chases/attacks? A flat race but with guaranteed wonky stuff that can be a catalyst for splitting everything up - people could nick a few meters on just a better corner technique, and be off before you know it. Normally the break is a break and the peloton will catch it, or a hill/mountain will let good climbers go up and down the leaderboard, but the Roubaix parcours makes for such an enthralling race.

 

[rubbershoes]

 

[Cid]

To get an aero benefit from deep rims, their width needs to be at least 5% greater than the tyre. Otherwise the airflow over the rim is a disturbed mess, and the deep section of the rim is pointless, just a few hundred grams of dead weight. So say the boffins with the wind tunnels. This is the seminal paper on the subject: PART 5: TIRE PRESSURE AND AERODYNAMICS

Because of the cobbles today, all the riders used 28mm tyres, or wider. On normal roads they wouldn't use anything wider than 25mm.

So, the 105 rule says that anyone using deep rims today should have got some which were at least 29mm wide. I don't think anyone did...I'm fairly sure that nobody even makes a good quality deep section rim that wide. Everyone was using their usual rims, which are typically 26mm wide. To my mind that was silly - they'd have been better off with shallow rims which are lighter.

According to someone on another forum, I got it wrong, because even when you don't obey the 105 rule you still get some aero benefit from deep section rims, especially in side winds, which there were a lot of today. Plus, today's race was flat, so a couple of hundred grams of unneccessary weight on each wheel is neither here nor there.

I suspect another factor is that the sponsors wanted their sexiest wheels promoted, and they are typically quite deep, 45 or 55 mm. They're all the rage. All the punters are lusting after deep section carbon wheels...they cost a fortune. Fantastic business for the bike trade.

Bontrager Aeolus:

Rovale Rapid CLX

Vision seem to be introducing a wider Metron, which anyone riding their wheels may be using. It does also seem to be one of those 'well, it's complicated' things... e.g same guy's explanation here:

1.So the 'Rule of 105%' is a pretty old school type rule of thumb. I conceived it in the early 2000's when we were experimenting with V shaped, parabolic, hybrid toroidal and early toroidal rims.. basically we found that they all would sort of work as long rim was at least 105% of the tire width measured almost anywhere on a deep rim. Granted there are differences in effectiveness of this which are the pillars upon which the various wheel companies have built their respective empires, but really, the rule holds from a very binary good/bad sort of perspective.

That is to say that there is more or less a near zero change of your wheel/tire system being fast if the wheel and tire are of equal width.. it really only works if the rim is wider. (and really only works if the rim is at least 105% of measured tire width)

This makes sense if you think about it from the point of view of the air... the tire is the leading and trailing edge of the wheel system and by the nature of it being built on an inflated casing..it really can't be aerodynamically optimized... so you need a rim shape that collects the separated air and smooths it out when you are looking at the front half of the wheel and a shape that delivers the air onto the tire in a way that it it most likely to 'close the gap' when you are looking at the rear of the wheel.. and to do either of these, much less both of them, the rim has to be a good bit wider than the tire.

As far as where the rim is widest is a sort of shell game...you can do it all at the brake track which makes the front half of the wheel very efficient in both drag and lift...but then the rear half of the wheel is less efficient and you have very forward centers of pressure and potentially unstable handling in cross-winds. You can move it to the middle of the rim and get pretty neutral handling but potentially at the cost of higher drag as the tire gets larger..or you can move it more toward the spoke bed which can do some cool things for handling, but can make some tire shapes no longer work well... so much that even tires within the rule of 105% don't work so well.. so we seem to be at a point where there are tradeoffs between total drag and handling, but for the average person were are talking pretty small differences in both.

2. So my point about the asymptotic relationship of width to rolling efficiency was mostly meant to point out that the 'wider is better' mantra isn't exactly true if you are considering pavement. As the returns are diminishing with width increase, there is very little benefit of say going from 30mm to 32mm and even less going from 32-34mm...and on smooth pavements, the difference is often immeasurable. The point here really being that there is some real benefit in rolling resistance and comfort moving from 23mm to 25mm and slightly less, but still measurable moving from 25 to 28mm but as you keep widening, the curve is so flat that the differences appear to be minimal to non-existent.. whereas the costs of getting there become ever higher. So for something like a Tri bike, the actual benefit (if any) of moving from a 28 to a 30 or 32mm tire is so small that it's almost certain to be wiped out by all of the other compromises that have to be made to get there...in particular, there just aren't really any aero rims that will work all that well with 30-32mm tires.

Now if you begin to consider other factors and surface conditions this will change. Our data looks primarily at various roughnesses of pavement and the Crr curves relative to tire width are pretty flat by the time you get to 28-32mm of tire width. However, if you move onto dirt, or gravel, or cobbles, the curves change and you find that wider tires suddenly have huge advantages again. This is where a bike like the new 3T Strada is pretty interesting and very fun (full disclosure, I am good friends with those guys so my opinion is likely colored by that!). Here is a bike that is built as an aero road bike that can handle tires at what seems to be the max width for both Crr and Aero when considering paved and related surfaces.. And when the surfaces move to gravel or dirt or worse, you move to something like and Exploro or an OPEN UP which can handle 40+mm tires which are smoking fast on the rough stuff.

3. Personally, I ride 28mm Corsa G+ on Zipp 303 rims which measure 29.8mm at 62-64psi and fit nicely inside Campy Calipers. This is a nice blend of comfort at some aero expense for our bad roads here in Indiana, but more importantly it adds some comfort to my daily driver which is a 1993 Team Issue Eddy Merckx MX Leader (Molteni paint scheme for those wondering). This bike is completely irrational, way too heavy, too stiff, terribly un-aero, and too overbuilt for most anybody ever (mine was originally built for the Eddy Merckx Podio team) but at the same time, makes me smile to look at and also very happy when I ride it. For me, the wider tires at lower pressures are of great benefit on our terribly rough roads full of pavement seams and such as they offer excellent handling and comfort (plus latex tubes.. oh so nice!)

If I were racing or at all serious about going fast, I'd likely generally be on 26-28mm tires (measured) on one of the very aero bikes out there for most events (likely run at 75-90psi depending on surface) and in the right conditions or the right events with high quality pavements I'd happily move to something like the Vittoria Corsa Speed TLR at 23mm (will measure 24.8-25.0 on wider bead seat rim which means I'd likely run 85-95psi depending on surface quality) for the combined Crr and aero benefits. The real key is having options and knowing when/where to use them and having wider rims and frames that can accommodate, certainly allow for more options.

 

[beesonthewhatnow]

That 105% rule is basically bollocks. Bicycle aerodynamics are extremely complicated, mainly due to the moving meatbag sat on top of it, combined with the ever changing yaw angle of the airflow involved.

 

[Cid]

Yes, that too. What Zipp did 10-20 years ago is pretty irrelevant.

 

[beesonthewhatnow]

The main problem with most of the (not even that old) bicycle aero “research” was that it all took place in a static state wind tunnel and/or a velodrome.

Now, if what you’re trying to do is develop a track bike, that’s fine, but it’s almost useless for real world road riding.

Aero wheels/frames etc work, that much is true, with the gains increasing the faster you go. For pros the extra 5W saving may be the difference between crossing the line in first or not.

For the rest of us the positive effects of shiny kit are all useless if the main item of drag - you - isn’t optimised. You’ll go a lot faster by sorting your position on the bike and clothing than you ever will by adding fancy wheels.

 

[sleaterkinney]

Think off the drag from all the mud on the bike etc.

 

[rubbershoes]

You’ll go a lot faster by sorting your position on the bike and clothing than you ever will by adding fancy wheels.

And, in my case, being less of a fat bastard

 

[David Clapson]

The main problem with most of the (not even that old) bicycle aero “research” was that it all took place in a static state wind tunnel and/or a velodrome.

Now, if what you’re trying to do is develop a track bike, that’s fine, but it’s almost useless for real world road riding.

Aero wheels/frames etc work, that much is true, with the gains increasing the faster you go. For pros the extra 5W saving may be the difference between crossing the line in first or not.

For the rest of us the positive effects of shiny kit are all useless if the main item of drag - you - isn’t optimised. You’ll go a lot faster by sorting your position on the bike and clothing than you ever will by adding fancy wheels.

That's rather obvious, don't you think? Nobody who thinks long and hard about aero wheels will fail to appreciate that you need to start with an aero meat sack. Lots of wind tunnel tests are now being done with a rider (not before time) and drag meters with pitot heads for on-bike CD measurement are starting to appear. I love all the new stuff that's being learned, although it does expose the limitations of my super duper wheels.

 

[David Clapson]

That 105% rule is basically bollocks.

Do you have real basis for saying that? Any links?

 

[David Clapson]

It's a lovely touch that Leporte has been stuffed into a clean jersey for his interview. Makes him look like the Frankenstein monster from an old black and white movie.

 

[beesonthewhatnow]

The new season of the walking dead looks quite good.