So I see 2-3 reports recently of people convinced their aero wheels with Tufo’s are slower than their training wheels. Certainly possible, but why?
I don’t have a power device, but I feel faster on my 404/Renn with Tufo S3’s than training wheels with Michelin Pro race clinchers, but I don’t have a direct comparison. I don’t ride race pace in training so it is hard to compare. I’ve been happy with my bike splits in races.
I do have to admit some confusion by my wife’s last two bike splits on 440’s with Tufo S3’s (the only two races she’s done with those wheels), but she was also out of town for a month (and couldn’t ride) before the races so there is more than one variable there.
Anyone else have a data point? How about a theory to explain this?
What tire pressure are you guys using? I’m running 125-130 psi. Both my wife and I have a 19mm front and 23mm rear.
I’m nearing the point where I need to replace my tubulars, but I need a little incentive to buy this month before my races in June otherwise I’ll wait until August before my 1/2IM and possible IM in Sept.
I have Tufo’s on my Am Class 58mm carbon tubulars and other than weight, rollout and spinup similar to my training wheels (Am Class CR-350 clinchers). I suspect that since Tufos can be infalted to 230 psi, some of us are not talking road conditions into consideration and are over-inflating the tires. I believe jhendric posted not too long ago about the consequences of over inflation, rolling resistance, and wasted energy - a lesson which I had already learned the hard way at the TT championships last year.
I raced on Saturday with a tufo on the front and a continental supersonic on the back. The back wheel was always catching the front but never quite got there.
Seriously I’d like to know an answer to this one. I inflate my tufos to 180 which I think may be too high.
This isn’t like saddle preference or bike color – purely subjective issues. When we start talking about something that can actually be measured, we should be reluctant to form conclusions with imprecise data. “Satisfying race splits” and “feels good” and “spin up fast” are not measurements that can translate to factual conclusions.
Tires can be judged in one of two ways – rolling resistance measurements done on a specialized rig, or carefully controlled road tests. Somebody on biketechreview.com posted a link to a German magazine that did rolling resistance tests, and the Tufos came out at the bottom of the pack. The high-end Veloflex and Vittorias scored well, as did Michelin Pro Race clinchers. Kraig Willet has a rolling resistance rig, and has promised to one day get around to testing some tires. When he does, I’ll be happy to pay the $14.95 or whatever he’ll charge for the results.
As for road tests, I don’t know of anybody having done the sort of definitive comparison required. A few astute users of power and speed data (like rmur and some others) are beginning to report at least some hints that Tufos are materially slower than other tires.
I did a 20k TT at 235 watts and 23.0mph with a 404/Tufo on the front. I did a 15mile TT at 222 watts and 23.1mph with a training wheel and Michelin clincher on the front. Unfortunately, that is not a definitive comparison because my clothing was different, my clipons were different and my elbows were closer together on the faster race. Body position was otherwise identical. So, there is a hint that the clinchers are faster, but I cannot say for sure. I’ve also done a few trials on my TT course that lead me to think the 404/Tufo is slowing me down.
I bought a new 808 wheel in clincher, partly because of these results. I would have switched to clincher anyway, but it’s nice to know I won’t be slower because of it.
Whoa Whoa Whoa, what are you guys talking about? I’m freakin’ out here. The Tufos I ordered for my new 999 (first tubs) just arrived (S33 lite). One reason iwent with them was that several people here recommended them. I don’t understand this thread. Can they actually be measureably slower? How much slower? Should I return them and get conti? I mean, how much slower could they possibly be?
I was also planning on putting S3 lites on my 909 wheels in fact I ordered them yesterday. Did a quick google and found a ref to the German Magazine test on the Conti web site. Here is the link:
Now I think that I found the download for the test results but I don’t speak German… my grandmother does but she no longer remembers her name. Here is the link to the German Mag.
Ash - any idea if rolling resistance for a given tire would be materially effected by the weight of the rider? Rmur and I seem to have some of the worst experiences and we are both over 85kg.
Also, I’m thinking of setting up a simple test and wondered if anyone else might have some input. Input that involves a lot of time or money or energy will be ignored ;). Anyways…here is what I thinking:
Set up road bike on computrainer with powertapped training wheel (Conti GP3000 clinchers at 115-120psi).
Warm up computrainer in ergometer mode with 15minutes at 200 watts and calibrate it to some number near 2.0.
Ride at 280 watts in ergometer mode for 5 minutes. Compare powertap average to the 280w computrainer baseline.
Repeat steps 1-3 with powertapped Zipp 404 rear (Tufo S3 lites at 155-160psi). Make sure Computrainer is re-calibrated to the exact same number as in Step 2.
Ok…so far this replicates what I did last year (where I found the Zipp to be 20 watts higher than my trainer). The reason I’m going to use 280w is because that is near FT for me on the computrainer. A significantly higher number (like +20w) will easily be felt (PE and HR) if the wheels/hubs/tires are different. Not very scientific but I’m going to trust my internal calibrator ;).
If numbers are significantly different I’ll put the trainer wheel back on the CT to confirm original reading.
Now for the oddball part of the experiment and I’m not sure how well this will work…
Suspend bike off floor and tie a “large weight”(35lbs?) to a string and then to the pedal. Place pedal horizontal to ground, lock rear wheel in place and look at PT torque reading.
Repeat #6 with Zipp (on same bike - 175mm cranks).
I’m so convinced that the Tufos are “at fault” that I’m going to hypothesize that the Zipps will read higher on the computrainer than the trainers (which they did last year) but that the torque around each hub will be the same when the suspended bike/torque test is performed. If rider weight is an important factor with regard to a tires rolling resistance that could be simulated by increasing the calibration number on the CT (just making the drum more tight to the wheel) but I probably won’t explore that. This also only addresses ‘watts lost’ for one tire rolling and not two. I’d have no idea how to extend data to two wheels (beyond doubling). I’m also not going to be willing to try different tubies, glue v. tape or running the tires at different pressures :).
I’ll just be doing this for giggles and I don’t claim any sort of real science is going on here. I’m already convinced that my race wheels are slower than my trainers and I know I don’t like using tubulars so this is just an fun/interesting exercise.
OT – the only real problem is that the contact patch shape on the CT roller is quite different than the one on the road. That might end up favoring one tire or another unfairly. Or, at least over- or under-stating the differences.
As an aside, do you know the area of the contact patch of a tire pumped to 120psi that is carrying 120lbs of weight? Simple algebra extends the contact patch area calculation to two tires, at a given pressure, carrying a given rider and bike.
I think step 6-7 tells you nothing. It’s not a static measure – rolling resistance is determined by how much of the tire flex is given back, rather than absorbed as heat, as the contact patch moves around the tire.
As for rider weight – I recall this being addressed in some article or another. Within normal weight ranges, tires will still end up in the same ordinal and relative rankings. It’s not like, “what’s good for the skinny guy is bad for the big guy.” Good is good, and bad is bad.
I just picked up my new Renn wheel from Frank. I asked him what tubular he would put on the disc, he told me a Tufo. He felt like they where best out there.
Sorry, I don’t own a computrainer, so I’m not an expert on this, but doesn’t the computrainer calibration involve a timed roll down test that would actually neutralize the difference in rolling resistance between different tires?
One disadvantage of sew ups that I keep mentioning and no one seems to comment on is that generally clinchers are more round, or have less ‘hop’, than sew ups. When I was using sew ups for general training in the 80’s I had a lot of trouble with this, and I always felt that this resulted in additional rolling resistance. In the case of your test, I would imagine that whatever degree of hop the tires introduced would subtantially increase rolling resistance because the tire is clamped in a rigid fixture. Actually, the fact that it is a rigid fixture could actually exaggerate the real world effect on rolling resistance of hop as compared to the real world, where the pressure on the tire is more or less uniform during each revolution of the wheel, as opposed to varying considerably during the revolution.
As I understood it, one of the advantages of the Tufo construction was that it was supposed to introduce less hop than conventional sew up construction. My S3 lites do have a significant amount of hop, but less than what I recall I usually experienced way back when with other sew ups. The hop is also smooth, i.e., it is a smooth amount of out-of-roundess instead of a ‘lumpy’ out of roundness.
I don’t have a power meter, but as useless as the test is likely to be, I am still trying to find a flat loop where I can do heart-rated based test where I swap wheels back and forth several times during the course of a session and the effort is a sustainable one at a given heart rate. I fully expect the variables to be far to great to find out anything meaningful, but I may try nonetheless because so far my subjective impression of my ‘new’ race wheels with the S3 lites is not very favorable and I’m not sure what else to do.
OT – the only real problem is that the contact patch shape on the CT roller is quite different than the one on the road. That might end up favoring one tire or another unfairly. Or, at least over- or under-stating the differences.
True. I would guess it would overstate it but I’m not really sure.
I think step 6-7 tells you nothing. It’s not a static measure – rolling resistance is determined by how much of the tire flex is given back, rather than absorbed as heat, as the contact patch moves around the tire.
I only thought those steps might help isolate the hub part of the equation. If the hubs are calibrated the same (or close) then they should show equal amounts of torque when the wheel is locked in place and a given weight is hanging from the pedal. I’ll admit that is very crude but it seems like it might work.
However the whole thing might be moot because as ttt points out - the computrainer calibrates based on a rolldown test and I have NO idea what effect has on this calculation. I do know that when I tested last year, the trainer was at (CT wattage + 5-10) and the Zipp was at (CT wattage + 25-30).
Without knowing the impact of the rolldown calibration I probably won’t waste my time.
Frank’s a quality guy, but what sort of data is “felt?”
Without data, we are guessing.
I’d like to once again beat the drum – factual claims/issues that can be resolved with data must be resolved with data.
One tire either rolls better than another one or it doesn’t. It really makes no sense to recommend a tire to someone without looking at hard evidence first.
Like Rick said, I think the contact patch being so much different on a roller compared to the road would make the results irrelevant. Also, the differences in psi on the computrainer do not equate well to the differences on a road with bumps and such. Presumably higher pressure on a perfectly smooth roller would lower rolling resistance, but that isn’t necessarily true on a less than smooth road.
So, does anyone have a theory why the Tufo’s might be 10% higher in rolling resistance. Perhaps if I (we?) understood the reason we could better develop a test. I just can’t for life of me figure out why a relatively high pressure tire, with relatively similar material and tread pattern would have such a significant difference in the rolling resistance.
I also wonder why, no one besides Michelin (as far as I know) makes perfectly smooth race tires. Tread on a TT bike tire seems completely at odds with the task. What is the point of little nubblies like a Conti Sprinter or similar?
A Michelin Pro Race tubular seems like the perfect tire to me…
Some Ritchey, some Hutchinson, Continental Grand Prix Supersonics, among others, have no tread.
A Continental Sprinter is not a time trial tire.
Continental recommends one of their other tubulars for TT’s.
If one were to select a tire for a very smooth surface like a wooden velodrome, one would want some tread. Otherwise you’re right, tread is useless for a bicycle tire meant to be ridden on roads.
I email Tufo a few weeks ago about this topic when the tape vs. glue vs. tufo tire topic was going on. Here is their reply.
"Hello Ron,
thank you for this one, for the time being we can not comment on the
subject, we have to conduct series of tests ourselves first to come to a
valid conclusion.
Maybe you can’t do this if you live in Oklahoma or you don’t have a powermeter… However, for anyone who does have a powermeter, this is real easy to test. I hope someone will – and report back the results.
Just find a 7-8% grade hill that lasts more than a few minutes. Go up it with steady power (say 250 watts) with the tubulars and then try it again with the clinchers. The low speed on the hill should laregely remove the aero factor from the equation, so what you’re left with is mostly rolling resistance (and a neglibible weight difference) Do a few trials. I’ll bet you’ll go a lot faster with the clinchers (even though they’re probably heavier).
You can also try to maintain the same speed with both sets of tires. I’ve done this. The tubulars always require at least 10 watts more to go the same speed. Tubulars suck. (I say this even as I’m trying to sell my tubular 404s and zipp disk)
Right now I’m running a Hed disk in the back. I have a sense that lenticular disks have slightly better aerodynamics than flat.
Someday, I want to try something really nutty like get a super light clincher rim like the American Classic magnesium and then stick a light cover (e.g. ch aero fiber, or durakote) on it. Make the first 700gm clincher disk.
