Can you explain what the numbers mean (54vs59watts and the .00289 vs .00316)? How are you testing these?

No surprise about the Corsa Speed...The new "Boss" has arrived.
As far as the SS...I've always found it illogical that the TT could be faster with regard to having the "safety shield".
That being said...I would feel more confident with the TT than the SS...I think.
Thanks Jens...much appreciated

X2

It's taken me enough nads to pick up some tt's instead of the usual gp4ks....supersonics for tris? The new ones have anymore flat protection?
Jens so now we have 2 data points. Is it safe to say the first lot were just a dud tire and not the norm?

Sorry. I should have spelled that out for people who haven't followed these tests in the past.

The watts numbers are the power that is required to spin the rear wheel on rollers at 25mph.

The .00289 and .00316 are rolling resistance coefficients (sometimes referred to as "Crr"). As really rough rule of thumb, each .0001 difference translates to about a watt of power when you're going 23-28mph. So a pair of tires with a Crr of .000316 will take about 2.7 watts more power to go 25 mph than tires that have a Crr of .00289.

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I think that's real safe to say. The first ones had very obvious flat spots. One was so bad, it actually hurt to ride on rollers with it. The ones I tested today were smooth as could be - not a hint of flatspotting.

The problem: how do you know if you have good ones or bad ones? I got the bad ones in February, so it's not like they're real old. (to their credit, Radial Cycles accepted the return). I think you have to test them on rollers or spin them, to look for flat spots......

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Now we just need to know how aero it is! Pretty impressive at how much lower in watts and Crr it is over the SS and TT.

I know this isn't totally germane to the discussion, but is the Corsa Speed the tire that is supposedly impossible to get on? Is that the tire that dkennison and slowman just basically walked away from at a wind tunnel? Have you had issues mounting for your tests?

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So the Corsa is tested in a disc but what wheel did you use with the SS? I think a Spoked wheel should be about 5-6 watts slower than the disc. Any chance you could put an SS on the same disc and run that (assuming it was tested on a different wheel)?

Jens: can you add the manufacture date to your post for the Contis?
http://www.continental-tires.com/bicycle/service/faq/tyre-construction

Supposedly. I am not particularly "ept" mechanically, and I manage it. It's particularly hard on the Hed wheels for some reason. If I thought I might need to change one in a race, I might consider a different tire. In my races, a flat means the race is over, so I don't really care.




I've previously tested the Corsa on the same spoked wheel as the TT and the SS. Crr on the disk is .00016 better -- about a watt and a half. And I don't think that has anything to do with the disk itself. It's more likely a drivetrain or bearing difference. I've done tests spinning a spoked wheel and a disk on the workstand up to 30mph. Despite what most people believe, the power difference is not measurable (less than 1 watt). Of course that changes when you have a 30mph wind blowing at the wheel.



It looks like 11/16, though it could be 12/16.

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Maybe I missed it but what wheel was the SS and TT tested on?

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Guess I need to man up and try to wrestle a Corsa Speed onto my Jet disc before Saturday's TT. I have an older gen Supersonic on there but it's in it's last days

First, thanks for the explanation on the measurements! Also.....why not test the TT and SS on the disc as well? Lastly, where would you say the Corsa Speed falls in the flat protection category compared to Conti.....more like the SS or TT?

The Corsa is more like the SS, no protection belt.

I think it is entirely possible that there were some SNAFU with the original production process of the new tire. Like many things in life, it does not pay to buy the first one off the line. Logic would say the Supersonic should roll faster than the TT.

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Is (are) there a typo(s) here?

Mike, IMHO the open-tubular cotton based tubulars are much less durable. I believe the cotton threads are much easier to cut than the Conti casing. However, what has me considering the switch is if they can be tubeless than should significantly up the protection assuming it can seal a small puncture.

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Thanks for the data Jens. Wow that Corsa Speed is fast. I'm a bit intimidated by the prospect of mounting one but that's just too much "free speed" for a guy like me to walk away from.

Do you still plan to do real world testing (on the road) with different pressures? While this is great data, I have to believe getting the pressure correct is actually more important than choosing between any of these fast tires.

Sean H wrote:

Do you still plan to do real world testing (on the road) with different pressures? While this is great data, I have to believe getting the pressure correct is actually more important than choosing between any of these fast tires.

Have you checked out Josh (Silca) data on this? Based on his showing, better to err on the low side than high side but you are talking about less than a <1 for 10 psi window. That is a pretty big target on say a HED JET PSI. Called at 85PSI for me at 155 lbs on skinny race tires.

https://silca.cc/...stance-and-impedance

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Yes I have read that and have been riding at 85-90psi on hed + rims (162 lbs). But I believe Jens disagrees with this low pressure trend and has said he's going to be doing some testing on it.

thank you for the testing, you now have me thinking i should run a SS on rear as well as the front!

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It would be interesting to see what Jens comes up with. I do notice that you mention "low pressure trend", and I know Jens is relatively new getting back into the sport from what I understand. When Jens was riding back then it was 13mm ID IIRC is standard. I don't think we are necessarily talking about a "low pressure trend", I think what this is about is adjustment for the wider rims, 21mm in case of the HED JET+. If you talk to the average person (the masses) they don't even know they are supposed to lower tire pressures with the wider rims. As a result you have the masses by and a large being the disseminator of information, often old and trailing advice.

To me the most important thing from Silca piece is that rolling resistance continues to falling, with higher pressures, until it doesn't. In which case there is a big jump. Anyone pumping these HED JET+ to 100 PSI should quickly realize how much they are skipping over the ground, or at least on the roads where I am at. To say 120 psi is the fastest result would be shocking and run contrary to what Silca testing shows but I am all for more information so I hope Jens can do it.

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When he does, I would encourage him to come up with a way to test at his typical race speeds. The energy input to the tires from the road surface goes up as a function of the speed. Low speed hill climbs, or protocols that don't reach those speeds, may not "see" the breakpoint pressure effect.

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