Putting a rack on your Italian road racer, front or back, would not be a great idea.

The only issue I have is no one is interested in addressing the point of diminishing returns.

After a certain point, wider tires do get slower.

Now, they may not roll slower but they are definitely slower overall once pedaling, standing and cornering are all taken into account. I've been thinking about this for a while and the only thing I have concluded is that there are losses while pedaling that are not present in the roll down testing and constant speed track testing done by BQ. Most likely the loses are from the increased flex of the tire as the rider is pedaling, effect would be greater for those with a more aggressive down stroke.

I think part of this is the lack of cross over between 700c wheeled racers who care about speed in a very real and objective sense and the market for 650b riders who care about speed in a more nebulous and subjective sense. No one wants to take their 650b bike to a training crit but if they did they'd figure out real quick that something was up with all the stuff they read in BQ and seen online, which led them to believe there was no difference between the speed of a fat supple tire and a skinnier racing tire.

While I think everybody can tell super skinny tires are faster than super wide ones, the current trend in racing is bigger tires.

And considering most people aren't racing, the tradeoff shows up in versatility.

Having already ridden the Masi more with the Vitts then I did with the FMBs, I will go with what works for me. I even put a set of similar wheels on it with FMBs and got the same result. The feel of a bike is what makes the ride for me. I am not driven by a need for performance. At 62, I am out to enjoy the ride. There is nothing worse to me than a bike that feels sluggish. Might as well be riding a POS in that case. As with many things, YRMV.

With tire pressure lower does it reduce initial sprint. Just throwing stuff out as the tire will have more give.

90% of my miles are the same 18mi/oneway commute. I find 23/25 tires at 100-120psi to be the most effective relative to flats and speed. I am 6t 185ib so a bit towards the bigger side which is a factor.

but it works ok with a smallish saddebag, because that's where it's built to carry all the weight

Oh absolutely, you should ride whatever you like that gives you the most enjoyment, but that’s not the point. The question here is does lower pressure help you to ride farther, faster and in more comfort than a tire that is pumped to a higher pressure. The sticking point for most people is the same…it doesn’t seem faster, it doesn’t to me either. Here’s the thing though, it doesn’t cost me a penny to lower the pressure and find out for myself. I’m 58 myself so if I can save a little battering on a 50 miler that’s a win. I’m no prophet for the low pressure set, but I am curious enough to try it and see if it works.:)

I can tell you this, if you're running your fine-casing supple tires at excessive pressure, you're wasting them

27 tpi Paselas only run well at rated pressure - all you get by lowering their pressure is sloppy handling.

My buddy Phil's early 80's Masi (repainted, too cheap to pay for the decals)

https://www.crazyguyonabike.com/pics...s_Masi.jpg?v=0

Not my cup of tea, but that's how he rides when we've credit card toured together.

As with all things bicycle there are so many variables. Here is my data set - I ride a pretty regular speed workout on a county road just west of town. I know exactly where each kilometer marking is so I can do things like ride the middle 8km section as close to 12 minutes as possible - that would be 40km/h which is mostly not possible for me without a tailwind.

I've been doing this for some time, and the road has been resurfaced in different sections over time. Currently half of it is pretty smooth but the western half is aged chip seal. Not surprisingly my best times are on a TT bike because I'm on aero bars. But I've also been dropping tire pressure over the years. The training tires on this bike are Continental sprinter tubulars (nominally 22mm) and I'm currently running them at 80/85 front/rear. I weigh 160lb. So far I haven't gotten any slower, meaning when I adjust for relative power I'm going just as fast now as I did when I used to run those tires at 100/120. I am definitely more comfortable and for me that feels faster. And the road is currently not as smooth as it was 5 years ago.

I suppose I could keep dropping pressure. I would bet that on the worst chip seal, something lower than 80 would be faster. But this feels like a sweet spot and I use the same pressures on all my road tires now.

+1

If my bike feels nimble, grips well during hard cornering, accelerates easily, sucks up road imperfections, and feels fast, that's all I care about. If my perception is "wrong", I don't care. My perception is why I ride.

I've experimented with tires and pressures quite a bit. I've had some cheap (not light, low TPI) tires that offered fantastic performance when I found the right pressure. Others (even lighter) were boat anchors in molasses no matter what I did. Due to whatever reason, there was no sweet spot to no found. There are so many factors involved with how a tire performs, I think it's best for non-racers to just use what works best for them. individually.

If you guys have ever ridden high-grade tubulars (linen casing), the new generation open tubulars and Compass EL that Jan worked closely with Panaracer to develop (+ Soma Supple Vitesse) are the next best thing.
The big-footprint Barlows on my CX frame run fast at 60/40 psi r/f and make it handle like a Ferrari.

As far as tire size and rolling resistance, if you're on a skinny tire, you're on a long oval contact patch, and the area of the contact patch is the same as the spherical contact patch of a wide tire. The 38mm Barlows at 350g are surprisingly light - not significantly different from 200g skinny racing tires.

Don't forget some here have been riding everything else for 30 years before that.

http://img.photobucket.com/albums/v7...P5110001-1.jpg

What size tire is that, and what rim is that? I zoomed but can't make it out.

That is a 27mm Compass Parigi-Roubaix tubular on a Mavic GL330 rim. The fork wouldn't quite fit the P-R (it was close) and I ran a 25mm Strada up front.
The beauty of tubulars is they are smooth as clouds from the get-go even on the coldest morning.
The open-tubular clinchers, after they warm up, it's really tough to tell the difference.
These are 27mm Vittoria Open Pave on Campy Moskva rims
http://img.photobucket.com/albums/v7...aaP1010005.jpg

Sort of. He suggested that it could be comparable to low pressures when on extremely smooth roads, but you catastrophically lose performance on rougher roads. You're basically making yourself less comfortable and versatile for no real benefit.

It's not something that get's totally ignored by the wide tire crowd, rather it's just not that huge of an effect. Wider tires are often coupled with lower rim diameters; the rotational inertia of a 650b can equal a significantly skinnier 700c, at pretty minor weight increase.

What if we go stupidly extreme? A ~53mm 26er Compass Rat Trap Pass tire is only about 200g heavier than a 700x25mm Vittoria Corsa. 26er inner tubes might be another 100g each heavier than 700x25s, if we're using butyl. The rest of the wheel is able to be pretty similar in weight, possibly even lighter. So for a cartoonishly fat setup, we're talking about maybe a pound of weight disadvantage (for both front and back) compared with a good narrow racing clincher? Even that's not all that catastrophic.

Sure, but we have no clue where the crossover occurs. Jan Heine has actually brought up this issue, and has mentioned he's trying to figure out where changing variables cause you to cross the line.

The really obvious issue is aerodynamics, and it's woefully under-tested.

Pedaling shouldn't really be an issue at the pressures being talked about. Even fatbikes don't seem to have much of an issue with it, and they go way lower than rando tires. The smoother ride may well subtly help pedaling efficiency, too.

The big limiting factor with cornering is grip. Wide tires at low PSI grip wonderfully.

When you say "concluded", does this mean you've tested the hypotheses?

//========================

On a related note, I installed my Rat Trap Pass tires on my '83 Stumpjumper conversion two days ago. First time I've tried wide supple road tires. Pumped them to 35/40PSI, and did a smooth pavement road route that I've done many times, including some very hard rides on my Emonda ALR 5. It's an out-and-back 47-mile route where I focus on a ~20-mile stretch each way and take a breather in the middle. Wind conditions didn't change much between when I started and when I finished the fine; slight tailwind out, slight headwind back. Wound up doing my best speeds on the route ever; averaged 21.1mph over the hard 40 miles, about 1mph better than the best I did on that bike when I had Thickslick Deluxe tires installed.
Not a great sample size, but these 53mm tires are clearly not slow.

thanks

I had similar experiences with 650b when I first started riding my Hetres. There is one hill climb where I had set my PR during a race on my 700c race bike that I crushed by several seconds on my 650b bike. I was blown away and really bought into the wide tires as fast marketing.

Ah I meant that more in a literal definition and not scientifically. I've got almost exactly a year's worth of strava data benchmarked with regular segement times comparing 650b to 700c that I've been looking at for a few days. No power data so it's not worth much to anyone other than myself but I've been seeing things like this, before the blue arrow is exclusively 700c after is exclusively 650b, same bikes for each:
https://drandalls.files.wordpress.co...0705.jpg?w=640

Whenever I ride this segment it comes at the same point in my ride, it's my go to to get out of town. It's flat with no lights. I see this and think if I'm doing something different. PE is the same, I weight about the same and carry similar amounts of water and the same tool roll. Road hasn't been repaved. I'm not sure what's going on but at least in this instance there's something happening that is not explained by roll down or constant speed testing in a controlled environment.

I don't have much at stake either way. I've come to appreciate that for my non-competitive riding speed is not really that important. I'll take the comfort, cornering grip and lack of flats I've experienced with wider tires over speed any day.

That's the point. It's the scientific method.

you're welcome.
Challenge tires are kind of their own animal. They're all fast. The beads on the clinchers can be a booger to deal with. Even the tubies are tough to stretch.
Across the board, they're 2mm wider than their rating. But they have a low profile, making their air volume the same as their rating.
This is why I had no problem with tall, skinny 27mm Open Pave in my Moser fork with room to spare, but couldn't safely fit Challenge P-R in front.
My buddy's daughter built herself a Shogun frankenbike this year and it came out beautiful.
It had 19mm tires (dead) when she bought it. My contribution was a set of used 25mm Challenge Strada clinchers. These proved to be the widest tire that would fit under her rear brake bridge.
She runs 70 psi, and she's fast on them.

Worse for me is feeling beat up riding O-ring sized tires pumped up hard on rough roads.

:p

A 15-20% difference!?

That's astronomical. I've never seen differences like that between my road bikes, and certainly not relating to tire width. For instance, I've had wide 26er slicks on my Stumpjumper for a while; before the supple Rat Trap Pass tires went on, I was using 2" Thickslick Deluxe tires. With the Thickslicks, the Stumpjumper was consistently performing a few percent behind my other road bikes, which are equipped with 23, 28, and 1.25" tires and are all pretty close to each other in performance.
(Before I was using Thickslicks, I had Continental Double Fighter II tires on the Stumpjumper. Even they only put me about 10% behind my road bikes.)
My Rat Trap Pass impressions are from one ride, but my wide-tire impressions in general are not.

I'm very certain that what you're seeing is dominated by an effect that isn't a subtle completeness issue with Heine's testing parameters. You're searching for a leaky pipe when you actually just got hit by a tsunami.

I get that, the person I was replying to was happy with his bike the way it “felt”. I was merely presenting the evidence that feel is not a good indicator of performance as outlined in the podcast, i.e. “feel” is not the point.

I follow this scientific approach to tire pressure....

you have the replace the **** with the appropriate word, just think of it as a puzzle.

http://****yeahhst.tumblr.com/post/36700606807/batcountryword-the-coupe-de-ville-is-not-your"

:thumb:

Yep. On the other hand, I'm not going to argue with someone riding a bike and just going by feel, fergetabout numbers, charts, etc. Somebody rides by me with 72 spoked 20" wheels with a 100" wheelbase and ape hanger handlebars, person has a big grin on their face, I'm giving 'em a thumbs-up, ring my bell, and smile back. :D

I think I'll try that on my home interwebs...