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Josh Poertner on Wheel Development for Paris-Roubaix
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Apologies if this has been posted before...

If you're into bike tech you should treat yourself and go and read Josh Poertner's amazing recounting of wheel development for Paris-Roubaix. Josh, thanks so much for the most insightful tech article I've read in years!

Part 1/3:
http://silca.cc/...ad-to-roubaix-part-1

Part 2/3:
http://silca.cc/...sures-are-everything

(Part 3 to come)

AndyF
bike geek
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Re: Josh Poertner on Wheel Development for Paris-Roubaix [AndyF] [ In reply to ]
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Re: Josh Poertner on Wheel Development for Paris-Roubaix [jackmott] [ In reply to ]
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A really terrific read! Bravo, Josh!

AndyF
bike geek
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Re: Josh Poertner on Wheel Development for Paris-Roubaix [AndyF] [ In reply to ]
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Very cool.
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Re: Josh Poertner on Wheel Development for Paris-Roubaix [AndyF] [ In reply to ]
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Great read!

I'd like to know what they found for power vs psi on smoother parts of the road... but then I still want that pony, too...
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Re: Josh Poertner on Wheel Development for Paris-Roubaix [AndyF] [ In reply to ]
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That's a fine article - thanks for pointing it out!
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Re: Josh Poertner on Wheel Development for Paris-Roubaix [eb] [ In reply to ]
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eb wrote:
That's a fine article - thanks for pointing it out!

Josh Poertner is one of the most perceptive and intelligent minds in cycling. Everytime he writes, I feel I'm so much closer to the action.

AndyF
bike geek
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Re: Josh Poertner on Wheel Development for Paris-Roubaix [AndyF] [ In reply to ]
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Great article!
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Re: Josh Poertner on Wheel Development for Paris-Roubaix [AndyF] [ In reply to ]
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Fantastic! Still need to read pt 3, but so for in impressed. Also, this shows all the people asking for tire pressure advice what's what :)
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Re: Josh Poertner on Wheel Development for Paris-Roubaix [TriathlonKid] [ In reply to ]
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Thanks everybody for all the kind words. Every time I write something like this I go back and read it and think about what a hopeless writer I am..so happy to see that the stories overcome my technical inadequacies!

I've been answering some questions over at the SILCA Facebook page, but if you have any you can post them here, I certainly don't know everything, but we work with so many teams that we know a lot and now that the race is over, can actually talk about a lot of it!!

Josh

http://www.SILCA.cc
Check out my podcast, inside stories from more than 20 years of product and tech innovation from inside the Pro Peloton and Pro Triathlon worlds!
http://www.marginalgainspodcast.cc
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Re: Josh Poertner on Wheel Development for Paris-Roubaix [AndyF] [ In reply to ]
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Really great read. Thanks for posting.

I ride:
Cervelo - P-Series/R3
GT - Sensor Carbon Expert

Supporters - Flo Cycling, Mount Bikes
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Re: Josh Poertner on Wheel Development for Paris-Roubaix [joshatsilca] [ In reply to ]
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That was really interesting - I've a question about the experimental design, did you use multi-factorial experimental design or a single factor at a time? did you set out a methodology to work this through at the outset? I've wondered about this with bike design in general.
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Re: Josh Poertner on Wheel Development for Paris-Roubaix [Andrewmc] [ In reply to ]
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Great question, the answer is both! For this particular project the first year was really spent just trying to understand the problem at hand. One major issue in the bike industry is that there is little to no shared data, and very few things have test standards that are really all that meaningful. This is good and bad because on one hand it lets tiny manufacturers who are building in their garage innovate and get to market without the crushing overhead of having to meet hundreds of standards, but for something like this, there was really zero data out there on what we were facing.

So our initial approach was incredibly single factor focused: we thought that we could make a stronger rim and that would do it. That very clearly did not work, so then we re-organized to use multiple teams each looking at single factor. The reasoning was that we could more quickly build up our directionals and magnitudes in this way. One great example is the conventional wisdom that larger tires are stiffer at the same pressure, and that higher pressures make for stiffer tires, and the combination would lead to higher impact energies being absorbed before bottoming on the rim.. all seems logical, but there was literally NO data anywhere on this so while we all felt it to be true, we had no knowledge of the order of magnitude of the effects..so one team worked just on that.

Ultimately the internal three teams converged with their piecemeal data and we approached with a multi-factorial approach for final refinement and creation of the ultimate envelope of functionality.

As an industry we are struggling greatly with this because of the way things are increasingly being developed as very highly optimized systems, yet we as consumers and users still want the ability to further customize or modify as we please. Nowhere is the risk as great as in disc brakes where there have now been numerous instances of pretty bad injury resulting from people wanting to break apart a system to use a lighter disc, or performing a hardware modification without understanding how things like mass can affect temperature. This is the same way the team that first year thought, 'the wheels worked great' after successful testing with 27mm tires and thought nothing of putting on 24mm tires for Magnus, so there is a movement coming to get people thinking more in a multi-factorial way than we have previously done.

http://www.SILCA.cc
Check out my podcast, inside stories from more than 20 years of product and tech innovation from inside the Pro Peloton and Pro Triathlon worlds!
http://www.marginalgainspodcast.cc
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Re: Josh Poertner on Wheel Development for Paris-Roubaix [joshatsilca] [ In reply to ]
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thanks for that - its been written on here before about "blind" tests of frame materials v's tire pressures, but "this" (your experience" with PR) seems to have presented an opportunity to take the accepted wisdom and blow it out of the water, the aerodynamic properties of tire size, rim depth and pressure.

So we see the trek's (its the only one I know of) with the compound that apparently improves compliance, and the new pinarello ridden by BW and Sky, but I think your experiment shows that putting improved comfort down to a change in a single factor fails to understand the complete system and I wonder how many of the manufacturers are doing / or doing multi-factorial experimentation with changes in tech e.g. you add the compound to the frame and test against a variety of rim widths and depths and associated tire pressures and determine whether changes in compliance are measurable - and I wonder if they really are measurable.

Thats really interesting work - that and the fact that no bike pumps appear to be accurate, which could explain the loud popping sounds you hear on race mornings as it warms up and everyone thinks they've inflated to X bar.
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Re: Josh Poertner on Wheel Development for Paris-Roubaix [Andrewmc] [ In reply to ]
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There are realistically 5-6 companies that are really looking at system integrated design and performance, and from these, I believe we are going to continue to see a drive toward the multi-factorial design approach that you reference. The problem with this, of course, is that we will ultimately lose some of the overall customizability of the total system which might be good or bad depending on how you look at it.

The compliance changes are definitely measurable and meaningful, but only in the systems that are done right..which is to say that we still have some issues with connecting benefits to features that may or may not be present in a given design. For example, on the compliance side of things, the Canyon 'aero' bike that Kristoff won Flanders on has a rear vertical spring rate that measures out comparably to many other company's 'endurance road' bikes.. so given the choice, most people would pick the 'endurance road' bike for the comfort because nobody has published the data to say that this aero road bike is similarly compliant. In this way, we have some aero road bikes that are as comfortable as other companies endurance bikes and some company's endurance bikes that are or aero than other company's 'aero' bikes... makes things kind of difficult, no?

On the popping sounds you hear, this is due to inner tubes being pinched rather than tire pressure increases due to sun and temperature. I've studied this 100 different ways, and if I take a wheel with properly installed tube, I can put it in a refrigerator, set the pressure at 100psi, and then move it to a 350F oven and not have an issue. We have tried in the lab to replicate this many, many times and cannot do it. I'm actually working on a paper discussing this, but from experimentation, I would estimate that nearly 100% of those race morning flats are caused by pinched tubes...and some of those I would bet come from rolling bikes around on deflated tires in an attempt to solve this problem in the first place!

http://www.SILCA.cc
Check out my podcast, inside stories from more than 20 years of product and tech innovation from inside the Pro Peloton and Pro Triathlon worlds!
http://www.marginalgainspodcast.cc
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Re: Josh Poertner on Wheel Development for Paris-Roubaix [joshatsilca] [ In reply to ]
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I really appreciate your sharing all this information, Josh! So much of cycling tech is hampered by myth and legend, and it's great to see some real and thorough tests results that are made available to the public.

Did you by any chance look at the effect of tire pressure on resistance in the smoother part of the course? I know it would be a small factor and not what you were focused on, but I'm still curious.
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Re: Josh Poertner on Wheel Development for Paris-Roubaix [joshatsilca] [ In reply to ]
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very interesting

as an aside why would you roll a bike around on a flat tire - I don't want to appear to be an idiot, but I was taught, insert tube, partially inflate sufficient to stop pinch, tire on the other side, work you way round the tire to make sure the tubes not caught between tire / rim and then inflate - who's rolling around on flat tires

that comment about Canyon's interesting - years ago I had a CAAD 3 - horrible bright yellow thing - which I would swear was the most uncomfortable bike I'd ever ridden - with the benefit of hindsight it was far more likely it was tire size pressure related than the frame alone, but everyone swore that they were the stiffest harshest rides known to man - I wonder though.....

I also wonder then about the difference in ride between the Canyon Ultimate AL and Ultimate CF as consumers we make assumptions about the CF v's AL argument but I wonder how much water it now holds.

The industry needs a degree of accepted standardisation - historically anaesthetic machines from different manufacturers had dials which if turned left on one would change a setting and right on another would change a setting in exactly the same way - that obviously caused problems if moving between theatres and kit - it does not seem beyond the wit of man to have a degree of standardisation.

Anyway, thanks for the info

Andrew
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Re: Josh Poertner on Wheel Development for Paris-Roubaix [Andrewmc] [ In reply to ]
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Carbon schmarbin, give me a Nemesis rim an FMBm 28 and the extra 1,000 Euros I saved on a fancy wheel and I will ride the cobbles all year and next.
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Re: Josh Poertner on Wheel Development for Paris-Roubaix [joshatsilca] [ In reply to ]
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Hi Josh, truly amazing articles! And thank you for sharing those stories with us.

My question is do you mind if I translate them into Chinese and share them in Asian(Chinese speaking countries) on multiple social platforms? For sure I will give you credit!


-Simon
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Re: Josh Poertner on Wheel Development for Paris-Roubaix [rruff] [ In reply to ]
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rruff wrote:
I really appreciate your sharing all this information, Josh! So much of cycling tech is hampered by myth and legend, and it's great to see some real and thorough tests results that are made available to the public.

Did you by any chance look at the effect of tire pressure on resistance in the smoother part of the course? I know it would be a small factor and not what you were focused on, but I'm still curious.

Interestingly, Sagan rode a Tarmac with 24 mm tires for the first 100K of this year's race and then switched to a Roubaix with 30/28 mm tires and low pressure once the cobble sections started. I don't know if other riders used the same tactic.
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Re: Josh Poertner on Wheel Development for Paris-Roubaix [Andrewmc] [ In reply to ]
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Andrewmc wrote:
as an aside why would you roll a bike around on a flat tire

Because if you believe the myth that morning sun will pop your tires, you might roll into transition with the tires deflated, waiting until the sun is up before inflating.



Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter
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Re: Josh Poertner on Wheel Development for Paris-Roubaix [jackmott] [ In reply to ]
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seriously, you'd (not you) believe a tire with a pressure range of 20-30 psi or more, people believe that if it had 25 psi in it, that the sun could raise that to 100 and burst it? thats nuts.......
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Re: Josh Poertner on Wheel Development for Paris-Roubaix [Andrewmc] [ In reply to ]
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Andrewmc wrote:
seriously, you'd (not you) believe a tire with a pressure range of 20-30 psi or more, people believe that if it had 25 psi in it, that the sun could raise that to 100 and burst it? thats nuts.......

very common belief
another one is that you have to deflate your tires before putting it on an airplane.

if you pumped your tires to 100psi and sent it into orbit the pressure would only rise to 114 =)



Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter
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Re: Josh Poertner on Wheel Development for Paris-Roubaix [craigj532] [ In reply to ]
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Interestingly, Sagan rode a Tarmac with 24 mm tires for the first 100K of this year's race and then switched to a Roubaix with 30/28 mm tires and low pressure once the cobble sections started. I don't know if other riders used the same tactic.

I was thinking of later stages of the race when speed really matters, and there are often solo breaks or small groups. I guess it isn't possible to switch bikes then, but I wondered what you might be giving up on the smoother sections and velodrome by optimizing for cobbles.

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Re: Josh Poertner on Wheel Development for Paris-Roubaix [jackmott] [ In reply to ]
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jackmott wrote:
Andrewmc wrote:
seriously, you'd (not you) believe a tire with a pressure range of 20-30 psi or more, people believe that if it had 25 psi in it, that the sun could raise that to 100 and burst it? thats nuts.......

very common belief
another one is that you have to deflate your tires before putting it on an airplane.

if you pumped your tires to 100psi and sent it into orbit the pressure would only rise to 114 =)

Funny that you mention this. The airplane thing is one area where you'll find some disagreement. And it has nothing to do with pressure change due to altitude. Mark Cote of Specialized firmly advocates deflating your tires just a bit before flying. It's a temperature issue. Your luggage is sitting in the un-insulated belly of a giant aluminum tube sitting directly in the sun often for quite a long time.

Of course, on the flip side of that argument is Josh's argument that you can go from -100F -> 350F without issue, and certainly there isn't a 450F swing in the bottom of the airplane. But it can get really hot in the belly of a plane, which is actually more relevant for other things you might pack in your luggage. But this is (part of) the reason for not allowing pressurized containers - and really, it's THAT policy that causes some airlines to want (aka demand) people to deflate their tires - on planes. It's temperature change rather than pressure change - more specifically, pressure change due to temperature change rather than pressure change due to altitude - that is the culprit.

"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp
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