Size matters... Article by the folks at Rene Herse Cycles

stu wrote:I can imagine towing one or more bicycle wheels behind a car on a flat road.  Each wheel could be loaded by a not-too-rigid weight resembling half a human.  The connection to the car could be instrumented to measure average horizontal force (force x velocity = power).  The whole thing would have to be enclosed in some kind of fairing to reduce the effect of air resistance.

This arrangement could compare different tires side-to-side on the same run and make it relatively easy to test on different road surfaces.  I'm sure it would cost more to build and operate than an indoor drum but not by orders of magnitude.

Interesting idea!  A bit like modeling a roll-down test.  I'm imaging two wheels side-by-side, each with its own strain gauge.  You'd swap positions periodically during the testing to try to cancel out any variation between the positions.
Hmmm... take two old bike frames, cut off everything forward of the seat tube.  Use the bottom bracket as the mounting point to connect to the strain gauge and tow bar.  Put 1/2 the rider weight on the seat..... 

Since we're talking about Rene Herse:

I just received, mounted, and rode a pair of 40 mm Strada Bianca Pro (not HTLR).  Compared to the 44 mm Snoqualmie Pass (Endurance) the SBP measure 1 mm narrower and 1 mm taller on the same rims, about the same volume.  I haven't ridden the Snoqualmie Pass for a while but the SBP seem at least as fast and comfortable and cost about half as much.  I also have the SBP in 36 mm, those have far better puncture resistance than the Snoqualmie Pass.

Regarding size differences, even the 4 mm difference makes the smaller SBP feel more like road tires on pavement.  With all the water in California I haven't tried the larger SPB off pavement yet but they're cushier on broken-up pavement than the smaller ones.  Without instruments I can't discern any difference in speed.

Angstrom wrote:

Interesting idea!  A bit like modeling a roll-down test.  I'm imaging two wheels side-by-side, each with its own strain gauge.  You'd swap positions periodically during the testing to try to cancel out any variation between the positions.
Hmmm... take two old bike frames, cut off everything forward of the seat tube.  Use the bottom bracket as the mounting point to connect to the strain gauge and tow bar.  Put 1/2 the rider weight on the seat..... 

Zipp uses a treadmill like apparatus with bumps to measure resistance. 

I’m personally not sold that wider is faster, but have no meaningful scientific data to prove otherwise. I have Strada Bianca HTLR 40mm on one set of wheels and panaracer agilest 28 on the other and the SB are noticeably slower sometimes. 

but they’re also heavy, and I ride in hilly terrain. Cruising along on a flat they are as fast as anything 

stu wrote:Since we're talking about Rene Herse:

I just received, mounted, and rode a pair of 40 mm Strada Bianca Pro (not HTLR).  Compared to the 44 mm Snoqualmie Pass (Endurance) the SBP measure 1 mm narrower and 1 mm taller on the same rims, about the same volume.  I haven't ridden the Snoqualmie Pass for a while but the SBP seem at least as fast and comfortable and cost about half as much.  I also have the SBP in 36 mm, those have far better puncture resistance than the Snoqualmie Pass.

I recently switched from Snoqualmie Pass to SBP HTLR 40mm. For me, I definitely feel like I can tell that these are slower tires, though not by a lot.  Not quite apples to apples as these are tubeless and only one of my SPs could be setup tubeless (front had a latex tube).  The SPs just had that road-tire-speed and feather-weight zing; however, the SBP feel plenty quick for the casual way I'm riding on-road right now and I'll happily trade the slightly slower feeling with the boost in puncture resistance. I was having lots of issues with the SPs toward the end (they were more worn and were flatting more frequently).  In thinking about it, the SBPs ride like I remember 38mm Barlow Pass EL tires riding (tubeless), but hopefully with more durability.  (The HTLR version of these is likely also a heavier tire than the non-tubeless so also wouldn't be surprised if those were a little faster -- with latex tubes, anyway.)

pushstart wrote:

I recently switched from Snoqualmie Pass to SBP HTLR 40mm. For me, I definitely feel like I can tell that these are slower tires, though not by a lot.  Not quite apples to apples as these are tubeless and only one of my SPs could be setup tubeless (front had a latex tube).  The SPs just had that road-tire-speed and feather-weight zing; however, the SBP feel plenty quick for the casual way I'm riding on-road right now and I'll happily trade the slightly slower feeling with the boost in puncture resistance. I was having lots of issues with the SPs toward the end (they were more worn and were flatting more frequently).  In thinking about it, the SBPs ride like I remember 38mm Barlow Pass EL tires riding (tubeless), but hopefully with more durability.  (The HTLR version of these is likely also a heavier tire than the non-tubeless so also wouldn't be surprised if those were a little faster -- with latex tubes, anyway.)

What casing did your Snoqualmie Pass have?  Mine were Endurance because I previously had a pair of Barlow Pass Extralight which had the puncture resistance of cheesecloth.  FWIW BRR rates the SP Endurance 5 or 6 W slower than the SP Extralight and rates the SBP only about 1 W slower than the SP Extralight (though the SP Extralight is more than 100 g lighter than the SBP).

So far I like the 40 mm SPB as a rough pavement and easy dirt/gravel tire.  I'm through with Rene Herse tires.

stu wrote:What casing did your Snoqualmie Pass have?  Mine were Endurance because I previously had a pair of Barlow Pass Extralight which had the puncture resistance of cheesecloth.  FWIW BRR rates the SP Endurance 5 or 6 W slower than the SP Extralight and rates the SBP only about 1 W slower than the SP Extralight (though the SP Extralight is more than 100 g lighter than the SBP).

So far I like the 40 mm SPB as a rough pavement and easy dirt/gravel tire.  I'm through with Rene Herse tires.

Oh I should have specified.  I was using the extralight casing on the Snoqualmie Pass.  It could very well be the lighter weight that I notice when riding around here (lots of rolling hills).  It seems unlikely that I could actually feel 1W difference, I agree! 🙂  

Yeah, I think I'm done with RH too.   Which feels good from the perspective of supporting good science, though I had many happy miles on EL SP tires.  (But more recently characterized by frustration with flats.)