I know it’s been discussed in different posts- with Josh at Zipp and many others- but a really good summary on tire resistance was just put up by velonews and Leonard Zinn. http://www.velonews.com/...rticles/12493.0.html
I race in the southeast- and ALL the top tri guys (not sure about the gals) use tubular race wheels- and I can’t find any UCI ProTour riders using clinchers on their TT bikes either… but there may be. I often have the fastest split or top 3 split on the bike in southeast regional tri’s that I do - and I race a tubi disc and tubi deep dish front. I’m strongly considering ditching the tubis… If you assume aerodynamics are the same- at least HED posts their tubular and clincher wheels as the same aerodynamics- and if the rolling resistance of clinchers is far superior… then how come no one- at least with the fastest times (in my area)- is racing on tubulars?
Are there people in ST- specifically racing clinchers b/c they feel they are faster? Or do most clincher riders choose to race clinchers- b/c their ‘easier’ to deal with? I’d like to hear especially from those that have ditched their tubis for clinchers- specifically for rolling resistance reasons… and their thoughts?
Lastly- has anyone compared (read anywhere) the importance of the rim/tire interface and how much that effects aerodynamics- versus that particular tire’s rolling resistance- and which is most important? i.e. Could a very low rolling resitance tire- be so-so aerodynamically if mated with your particular model wheel- say Zipp 808 or Hed Stinger 90- and that mating hurts aerodynamics and eventual speed more than the boost from low rolling resistance? The nice chart in velonews- listing all the tires in rolling resitance order- seems to be 1/2 the story- if the rim/tire interface is equally, more so, or maybe even less so important…
Somehow or another, you made the jump from talking about rolling resistance in a tested environment to being the fastest tire in a triathlon/road race.
There are other factors to consider when chosing a tire/wheel, such as:
puncture resistance
road feel
cornering performance
ability to change a flat
weight (as you mention)
sponsor
brand loyalty/familiarity
access to parts/materials
installation
being stuborn
Perhaps the last one might be the key. If the fastest guy in your region is riding tubulars, then tubulars are the fastest tire in your region. There are lots of books written on GroupThink.
(remember me from your days in NJ? You have a brother Dave?)
You might want to check out www.biketechreview.com, if you haven’t already. Some seriously fast guys with a penchant for analysis habituate that forum, including a national (non-US) champion and a former teammate of Greg Lemond.
One of the most difficult things to determine is if someone is successful because of their equipment choices or in spite of them.
I should clarify a couple parts of my post… I have ridden well with tubulars (obviously lots of people do)… but is it worth it to race on clinchers- so you can ride even faster? I mean- if my bike split- ended up being 30 seconds faster for a 30 minute TT- that’s huge- a free 10 seconds per mile for a 5k run. My competition is riding on Tubis- at least here- and if clinchers were even faster… I could make up for my slower runs.
puncture resistance – very important- but I think most high quality tubis or clinchers are relatively puncture resistance for – especially if these tires are saved for race days. I have gone thousands of miles on 210 gram clinchers- flat free.
road feel – not a big deal for me… it’s a Time Trial- generally short- say 60 minutes or under- top clinchers have a really nice feel- such as the vittoria open evo pro
cornering performance – most TTs have few corners- and I don’t think that’s an issue- many Pro Teams do all their non-TT on clinchers- again vittorias are very nice
ability to change a flat – I’m just focusing on the race- forget about ease of anything when not racing- these are RACE wheels
weight (as you mention) – If I’m doing a hill climb TT… I would use different wheels- otherwise- weight truly is non-issue when comparing to aero
sponsor – don’t have one- and zipp/hed… etc produce clincher and tubular models…
brand loyalty/familiarity – couldn’t care less
access to parts/materials – ? in the U.S.?
installation – non-issue- I want speed.
being stuborn – (aka ‘tradition’ so far- I think this could be the one…
The way I read the research is…if you’re riding in a straight line on smooth/clean pavement, then probably. Otherwise, “fast” is dependent on many variables in which rolling resistence is one (albeit the majority).
How do you REALLY know you would be 30 seconds faster? You don’t. It’s based on the science. Fast is fast. Performance is performance.
Since I’m mostly a “roadie”, I’ve seen several REALLY fast tubie loyalists change over to clinchers, but not at the rate of amatuers changing to tubulars. Go figure. These REALLY fast guys don’t use rolling resistance as their reasoning, they just didn’t want to fumble with tubulars anymore and felt the clinchers were “just as good”.
I train and race on clinchers, but mostly because that’s what I’m comfortable with. Yeah, I had tubies on the track for a while – a pain in the ass mostly.
I don’t really care about any small differences in rolling resistance – I’ll have a greater performance difference if I eat that extra plate of pasta two days before than what I’d see on tubies come race day.
Stubborn? Maybe. But I think being comfortable with your equipment makes a bigger difference.
Looking at that article they are all still comparing apples to
oranges. In the article they stated that aerodynamics improves with
tire width under 23mm and in tubulars like the Tufos rolling resitance
dramatically decreases with PSI over 140. From a the California TT
website the tips of the pros said to use tubulars with high PSI. So
the optimal testing would be the clinchers at the PSI they tested and
the tubulars at their max PSI or very near then compare Rolling
resistance and also the aerodynamics in a windtunnel. Then we would
get the fastest reacing tire. Till then I think we should look at what
the pros like Lance use since he spent hours in the windtunnel, I
doubt he wouldn’t look at rolling resistance and aerodynamics of the
tires. Lets check out the Tour and what they use this year.
Several of the tips on the SoCal TT series are what I’d describe as friendly advice for people you know you are racing against.
For example, Continentals are among the slowest tubulars you can buy. Also, gluing tape is vastly inferior to standard glue. Neither of these things will put you at risk, but it will certainly ensure that if you are basing your racing off those tips, someone from the SoCalTT series knows they have a leg up. Tufos are THE slowest you can buy, so again, it’s not like they are recommending tires you actually want to use. They are recommending tires they want their competition to use. Same with the clincher recs. Absent are Vittoria, Veloflex, Michelin, Deda, Dugast and all the other really fast tires. Coincidence? No.
They also emphasize weight, which is a bit of a misdirection. Light is good, but aero is better. Using a superlightweight aero bar over one that is more aerodynamic is a bad decision.
Tipping your extensions slightly down is also a very bad idea. Jan Ullrich is the only one in the photos they show who actually does this. They also fail to show any of the updated CSC picks. CSC also looks like they are pointing their aerobars down, but it is really just pad/extension height difference.
The folks at MIT have also shown gloves to be slower. Most of the TT’ers now have skinsuits that cover their hands, but they never wear gloves with a velcro backing certainly, as shown in the picture.
The bottle-on-the-frame advice is also not universal. Many frames are slower with bottles on them.
I agree with your comments but the aerodynamics at 40-50km/h outweight everything else. There is a great discussion on this on Wattage group in Google groups with article references.
Just because rolling resistance is a smaller component of power loss (~10% at 50kmh vs. ~20% at 30kmh, assuming flat ground), it doesn’t mean it can be ignored. Bottom line, even small power differences can make a huge difference in terms of racing. How many minutes separate the leaders in the TdF? Tires do make a difference. If someone said you can have 1% more power for free, every pro in the peloton would take that…
I have a set of 50+mm front/disc - tubulars - Vittoria EVO KS - glued with Mastik. I have a set of 50mm clinchers with latex tubes/mich pro2 race clinchers.
I rode both on nice roads at IM pace (I tested at 20 mph but race slower than that…).
Clinchers were 30 sec/hour faster in low wind conditions (very rough estimate).
Clinchers feel better to me…
Both pumped to about 100 psi.
I raced at IM CDA on the clinchers…
I will do further testing at diff. speeds and cont. to look.
our household uses clinchers because they clearly faster in the rolling resistance dept., and are a lot less hassle than tubulars’ insanely time-consuming gluing, de-gluing, re-gluing processes (all very time-consuming ifdone right, that is). also, tubulars have more than a few troublesome issues that i have never heard good solutions for:
-i don’t have the money to toss $50-80 dollar tires when they flat,
and i don’t have the time to be an expert seamstress to repair them.
clinchers are modular: you can easily toss or fix just the part that
is damaged. and you need not use rim tape at all: we use veloplugs on
our zipp clinchers.
-they tend to roll off the wheel during cornering if the glue and rim
gets hot as it will during extended braking on fast and long downhill
descents in warmer weather.
-they are nearly useless if you have to change one in the rain: the
spare tire, even if properly prepped, does not want to stick to the
rim when everything gets wet. you basically have to ride like grandma
the rest of way home praying the air pressure holds the tire on.
-they are nearly impossible to glue on perfectly (and i mean perfectly)
straight, as compared to the dead-on mounting precision of
high-quality racing clinchers.
and if it helps, folks in our household have been winning races (triathlons) overall on clinchers as far back as 1991 and as recently as 2007. as far as I’m concerned, ‘tradition’ can go take a hike …
I’m slow (except when my weight gives me an advantage downhill)
I ride clinchers, mainly because I’m cheap, they’re easier to change, and I’m familiar with them.
For years people have been talking about the advantages of this whee or that wheel for aerodynamics.
I think the tire and tire/wheel interface is equally important. About 10 years ago I bought some Michellin clinchers that I think must have been the most aero tire out there. Unfortunately I don’t remember themodel, but I haven’t seen anything similar since.
The two features I really liked were:
When inflated, the tire wasn’t a nice round curve at the front, it appeared to have alot more tread thickness in the middle so instead of a circular profile, it was more eliptical or V shaped. This is important in my opinion as it gives a much better air flow around the side of the tire, keeping the air attached, rather than all turbulent, negating the effect of the deep rim in the slipstream.
what is normally an indentation where the tire and tube join, this tire had a thicker sidewall, so the tire faired into the braking surface of the tire in one smooth line rather than dipping in then, back out for the rim, again, keeping the air attached to the tire/wheel, improving the benefit of the aero wheel behind the tire.
I’m not sure how much difference the above would make (particularly in a 23mm tire, as opposed toa 21mm tire say) but why buy the less aero tire (ie a standard tire) for no reason, as the standard tire isn’t likely to be *more *aerodynamic is it?
(Currently I ride a Kenda tire (again I forget the model) but this is mainly because even at high pressures, it is so smooooooooth to ride on and so supple that it grips well in corners etc. This is important on the terrible tar and gravel roads here in NZ)