Basically, I like data. My experiences have led me to favour 'classic' French rando bikes, but generally speaking when I'm making my mind up about something I want to see some information. Years ago, everyone thought 20mm tires were best because the contact patch was thought to be smaller, and thus there was less friction. This turned out to be mostly false, but it persisted for years. Why not test it? Why not publish how the tests were done, so people can make up their own minds? Why not 'real-world' tests? Heine seems to be the only one who really does this...I don't want to hear a bike is 'laterally stiff, blah blah'. Why not try and quantify which one is actually faster? This has value to me. Where else can I get this?
I understand what you're saying about bias, but I don't agree with your conclusion. If you set up a little online bike shop, doesn't it make sense to offer your customers some actual data about why your tires are better? Alternately, if you test fifty tires why would you not sell the best of them?
Edit: Additionally, I don't think 'impartiality' is really necessary. It's okay to have an opinion, or even a bias, if the data is accurate and provided in a transparent fashion.
That's kind of funny because I started randoneuring on a 70's Peugeot I used that bike for a number of years and did my first 1200k on it. I switched to the modern bike because the Peugeot beat the crap out of me. My C-40HP accepted 25's and that's pretty much what I rode. When I got the C-50 I was a little chagrined that the 25's rubbed on the rear chainstays so I had to switch to the 23's on that bike. To be honest I couldn't tell the difference between them. I think most people would be hard pressed to tell the difference between a 23mm and 25mm tire of the same make and manufacturer.
The important thing to take from this is that there is no right or wrong way to do this. The right way is the way that gets you to the finish and allows you to meet whatever goals you might have along the way.
As far as the bias at BQ we'll just have to agree to disagree. As far as I'm concerned it's no better than the "engineering" that comes from Santana's journal or any other proprietary journal. As long as the writer has a personal or financial stake in the outcome I treat it as if there is a bias.
If anyone is interested, PM me.
It's not my method. Google 'robert chung virtual elevation' and you can read about it and see how people are making use of the technique.
I just happen to be willing to help people get started with doing it themselves. It's a 'pay it forward' kind of thing for me.
You switched from 27" to 25c to 23c, kind of a backwards progression to most riders' experiments. most riders will first stick a 25c tire under the ganks of their bike which previously only saw 23c tires because thats' what the bike came with.
The feeling changing to 25c is going to be tangible to riders attuned to their bikes. The rider may not be able to qualify what exactly it is about the 25c that felt different, but noticeable it will be.
observations like "I felt a little faster" "the chipseal seemed smoother" "The bike stuck in corners better" "less tired on normal routes" and "less vibration" will be widespread, not infrequent.
I've seen this happen in a number of regulars at the shop making the switch to 25c tires, and the shop monkeys too.
The world view is extensively colored with studies funded by interests with a financial stake in the outcome. For example- do you think cholesterol in eggs is good or bad for us? Or, how's chocolate milk as a recovery drink?Quote:
Originally Posted by homeyba
Yep, companies often fund studies to further their interests. In the case of Jan's "rando rollout", I don't think there's much bias evidenced in the tire roll-out test data.
You mean, like how Jan Heine has done it.Quote:
Originally Posted by steamer
http://janheine.wordpress.com/2011/0...-used-to-ride/ and successive articles.
I'm skeptical about his test results, but only in the sense that everyone should always be skeptical about test results. Fortunately, as you point out, one can always do one's own testing, which I've done to the extent reasonable and possible. With rare exceptions, I coast downhill on my 650Bx42 Hetres at least as fast as anyone I know on whatever tires they are riding and faster than many. It's pretty clear that quality of construction and materials is a major influence on rolling resistance, just based on my own experience riding different tires. In 700x32 tires, Panaracer TServ's are clearly slugs compared with Panaracer Pasela's with Tourguard, which are clearly slugs compared with Panaracer Pasela's without Tourguard, which are clearly slugs compared with Grand Bois Cypres. No big surprise there, TServ's are designed for heavy-duty city riding with flatproofness as a premium and rolling resistance is not even a consideration--they even say on the sidewall "TServ for Messengers". The Pasela's of either category are designed more as a touring tire. The GB Cypres is designed with rolling resistance as the primary consideration and assume that you will be fast enough that any flats encountered will still leave you faster on net. That's been my experience with the Cypres, I've only rarely gotten flats. But it's my understanding that areas with Goat's Head Thorns will provide a different experience!
WRT "bias", it's a reasonable concern. But Jan published the methodology and the numbers. It's kind of hard to see how bias could intrude. Which is why I consider the "bias" claims more Ad hominem than reasonable counterargument.
Norman Rapide from narrow Vittoria tires (26mm, 25mm measured on the rim) to Grand Bois Cypres (30mm, 31mm measured on the rim), did not result in slower speeds on one of my regular rides. Road irregularities that would have had me out of my saddle using the previous tires instead were approached sitting in the saddle and pedaling. Now I'm accustomed to the feel of the new setup, I'm going to get more measurements on the loop and see if my time drops when compared to the old setup.
Another data point is my Bilenky 650B tandem. On some rides I've been on with other tandems, when they would get into sections of road where the surface was rough (they were riding on narrow tires, 25-28mm typically), they'd be out of their saddles standing on the pedals while my wife and I would continue pedaling. On those sections, we would close the gap and sometimes pass them. When the road smoothed out, the other tandems would start pulling away or catch up and pass us because they were strong teams. Given the strength of the other teams, they should have consistently stayed out front, but they didn't and I attribute that to the tires we were riding.
I again want to repeat that my comments and thoughts on the matter are purely anecdotal, but appear to be in line with testing that Jan Heine has done in recent years.
Cigarettes are good for you too, Marlboro has the research that says so. They have methodology and data too. You can call that ad hominem but then maybe you could point to all the back up research by unbiased researchers that verifies BQ's findings? That may come and it may not but until then I'll view their findings as just another baised sales pitch.
Ah yes, here it is:
From the blog post in which Heine address this very issue: http://janheine.wordpress.com/2012/0...-what-we-like/Quote:
When the Mitsuboshi 650B x 38 mm tires were discontinued, I had an idea for a stop-gap replacement: What about using the mold of the Panaracer “Col de la Vie,” but with the Grand Bois casing and tread material? The result was the Grand Bois “Ourson.” Unfortunately, the “micro-knob” tread pattern of the Col de la Vie dominated the experience of riding the Ourson: It was not as fast as the other Grand Bois tires, and the knobs squirmed and flexed, making the Ourson less than ideal both in a straight line and in corners.
Others did not share our concerns, and raved about these tires online. It would have been easy leave it at that, and not review the Ourson at all, but that would not have been honest. The review in Bicycle Quarterly was harsh: “We do not feel that the Ourson warrants the extra cost [over the Col de la Vie].” When we did this, we knew that sales of these tires would collapse. Our stocks of these tires remained in the warehouse for years, until we finally closed them out when the completely new and excellent Grand Bois Lierre was announced.
Let me make this clear because I don't want anyone to think that I'm trying to besmirch BQ's reputation. I've not seen anything that makes me question their integrity. My point here is that BQ is a sales tool just like the Rivendell newsletter, Tandems and Tandeming by Santana and many others. If you choose to take what they write as gospel and free from bias you are more than free to do so.
That's apparently where we differ: I don't see BQ as a sales tool. I mean, I suppose it is possible that Jan started the magazine as part of a far-reaching conspiracy-type thing (he didn't start selling bike parts until years after introducing the magazine) but I figure that's pretty unlikely. I think his answer ("I couldn't find the parts I wanted to use myself, so decided to start importing them) makes more sense.
As you point out, he could actually be fudging his numbers. I simply choose to believe that he (along with the people working with him, assuming he didn't make them up too) is not publishing a magazine filled with blatant lies for the purpose of selling small numbers of high-end bike parts to a tiny minority of cyclists.
At least Jan took the time to do a rollout test and publish the numbers. He's got some hard proof that 25c tires are faster than 20c tires generally speaking. We don't have to rely on the whims of racing :innocent: to trickle down to rando....
BQ a sales tool?
Egads, the world must look like one huge rolling advertisement. Avoid all magazines and television.
BQ is definitely something more than a J Peterman catalog, It's a magazine targeting the rando/classic cycling community, dedicated to the traditions and origins of randonneuring, or something thereabouts.
Jeesh. So the guy wanted faster, big volume tires.
The virtue of the newer "wide" wheels (for example, like the Zipp Firecrests or the new Heds) is that you don't take as much of an aerodynamic hit when you use wider tires (though we're still talking 25mm as opposed to 20's or 21's). If you take a look at the cross-section of these new rims they're sort of like a tailbox on a recumbent bike: they don't affect the frontal area but they do affect the Cd of the tire-rim combination. That's at zero yaw -- at non-zero yaw (and randonneurs are likely to see a wider range of yaw angles than racers) the newer rims do even better than box rims. Bottom line, if randonneuring were a larger segment of the market more effort would be spent on designing "wide, low-speed, high yaw" wheels and tires.
As a comment on the BQ Crr testing methodology, note that it requires at least two other people as timers (one at the "entry" to the timing trap and another at the exit), and you have to have a way to synchronize their timing so you can get a true estimate of your elapsed time as you roll through the trap. Since they're only measuring elapsed time, you're limited in the error estimation. As you know, there are ways to get around these limitations.
I have a test planned soon to compare my 25mm Duranos (actual width: 24 mm) to my 32mm Vittoria Rando Hypers (actual width 31.5mm). I suspect the Hypers will produce a lower Crr (based on how they feel to ride), but of course will most certainly have a higher CdA. I am mounting both tires on 19mm wide rims, so the CdA penalty for the fatter rubber will be in full effect. I suppose the more detailed way (i.e. not a rule of thumb way) of looking at the tradeoff issue is to just plug and chug the Crr and CdA figures associated with different tires into a calculator (like the online Gribble calculator) for some anticipated moving average on a randonee and see which CdA/Crr pair results in lower power required.
As a timely and perhaps interesting aside (interesting if you're obsessed about these kinds of things and if you are there may be therapy indicated in your future) a rim manufacturer was just in the A2 wind tunnel yesterday checking out which tires of which widths had the lowest CdA when mated with their rims. To repeat, this was a wind tunnel -- they weren't checking out the Crr characteristics but just the aero characteristics.
[Edited to add] Of course, this doesn't have much to do with rando speeds (except for the non-zero yaw part) but it does give you an idea of how people are interested in the trade-off between Crr and CdA.