Bob Dopolina 

Here we agree.

If I need testing done for my customers I pay professionals (who have some really cool equipment) to do it for me.

Destructive frame testing is, by far, my favourite.

frenchyge

Not sure if you looked at FLO's data, but contrary to the artistic renditions of the tire shapes and contact patches between the 23mm and 19mm rims, the actual differences were only 2-3% difference in length and width. With your experience in tire construction and testing, would you feel that amount of difference is sufficiently game-changing to say that the existing data is no longer relevant? Before you answer, consider that the contact patch difference between the 19mm rim at 120psi vs 80psi was *4-5 times* the difference between the wide and narrow rim.

It seems to be one of the basic tenets of marketing strategy that one should first declare that the new product is so game-changing that all previous products are obsolete, no comparisons are valid (apples vs oranges), and previous data no longer applies. I think one of the points of this thread was to discuss whether or not that's true as applies to wider rims.

Bob Dopolina 

Actually I was following the thread that sparked that cut and paste project. I was pretty impressed with how quickly they responded to a question in the thread and put together not only a test but a video to post along with it. It was pretty amusing.

I don't have strong feelings either way. I was engaging in a bit of chain rattling...(guity)

But ...the difference in the contact patch between wide and narrow rims shown was on a flat surface, I'm not sure what the difference would be on a roller and if it would become significant or not. That was a question that went unanswered.

Considering the actual size of a contact patch (about the size of a dime) small changes should have some impact. If you accept the statements by Continental that their Black Chili compound has a lower rolling resistance because the molecules in their compound are smaller then changes of 2~3% in the shape of a contact patch could also be statistically significant.

I don't know if I would call it game changing, though and I don't know if it would render previous data irrelevant or not but it is a legitimate consideration, non?

Since you've asked lets consider construction. If you look at a high TPI tire how many threads are deflecting at any given moment? Does a 2~3% change in contact patch result in a 10% change in this value or no change at all? Would a less pliable compound used in the casings, of say a Tufo tire vs another brand, alter this number in a significant way?

What about dual compound tires? Part of the challenge with them are compounds in the tread that behave in slightly dissimilar fashions. How would they handle a small change in the way the forces are introduced to the tire because of a change in the shape of the contact patch?

Tires, tubes, rims (etc) are a system and small changes to one component could have impacts on another part of the system that are unanticipated and could become signifcant. Is this the case here?

That's a pretty accurate depiction of the status quo.

Honestly, I was looking for a clarification when I got sidetracked by a childish attack. I'd like to see some real discussion on the issue as well but don't appreciate having 'facts' rammed down my throat (not meaning you).

The converstation thus far has been focused on a very narrow facet of the question (no pun intended) and it could be worth considering the effects from a much broader perspective.

For instance, maybe the effects of a wider rim are also somewhat dependent on the tire mounted on that rim? And the pressure used (this has been addressed somewhat)? Or whether the tube is latex or butyl?

FLO Cycling

Which document are you referring to? This one...

Crr values are typical for very smooth surfaces - Crr on typical road surfaces may be 50 to 100 % higher
Tire Pressure = 120 psig unless otherwise noted
Speed ~ 51 km/hr (54X13 - ~ 100 rpm cadence)
SRM Pro Power Measurement (Zero'd before each test run - Calibrated every 6 months)
Crr Calculation from Tom Anhalt's Spreadsheet
Tacx Rollers (79 mm PVC - 26 cm spacing) with Hinged Front Fork Mount
Test Run time ~ 2 minutes
Power per Wheel at 25 mph with 100 lb load
Rear wheel load adjusted per morning weigh in
Each tire warmed up for > 5 minutes before testing
Aero position used for all tests (to hopefully maximize repeatability of rear wheel load)
Control - Ritchey Fortress and/or Michelin Pro 2 Light training tire tested first and/or last each test day
Raw Speed Data was corrected for tire roll out prior to Crr calculation
Ambiant Temperature Range 60 - 75 F (typical 5 degree F range per test day)
During the tests tire T increases from 20 - 40 deg F (low Crr tires heat up less than the higher Crr tires) - (Estimated T rise on a flat surface is between 4 to 8 F)
Estimated Day to Day Repeatability Std. Dev. ~ 1.3 %
Corrected Note on Tubular Gluing - Identified Shop Glued Tires Separately - Previously these had been lumped with Properly Glued (Defined below)
Data is included on a set (*) of Vittoria tubulars tested by "properly" gluing each tire onto the existing glue bed - BTR thread "Vittoria Tubulars including the new 320 tpi CX ".