chas58

I'm more worried about start and stop. Accelerating from a stop is a lot more fun with light tires. But, if you are just going out for a cruise without stops, weight doesn't make much of a difference.

Heck, on the velodrome we use some pretty heavy wheels for longer time trials (or the 1 hour record) because when you don't stop, the aero makes a bigger difference than weight at those speeds. I'm not using those heavy wheels for sprints though! LOL.

NoGears

I can't be bothered by a <1mph speed reduction when the level of comfort difference is much greater than that. But I don't race either.

chas58

"Assuming the same tire, 42mm tires are going to be slower than 32mm tires"

There is plenty documentation proving that the bigger tire is similar or faster than the smaller tire (due to contact patch shape and sidewall deflection, as well as ability to conform to road surfaces).

On the flip side, the bigger tire is heavier, and will accelerate slower from a stop. If you are going over 20mph, you can make an argument for an aero disadvantage to larger tires.

And, at 10-15mph, in a steady state, the larger tire isn't going to be slower (assuming same casing, materials, tread, etc).

chas58

I understand your point of view. And that BQ may be a little biased. And that lots of testing has been in the 23-28mm range

Here is another point of reference showing larger tires. Doesn't seem to be much of a difference here (other than the obvious fact noted in the article). Read this and see what you think.

Schwalbe Marathon 32, 37, 40, 47 Comparison

HTupolev

Actually, that particular comparison sort of supports the notion of wider being slower. The 37mm was slightly ahead of the 40mm, and in theory wider tires should have to have better crr to achieve similar overall performance. On the other hand, it's also clear in the comparison that there are relevant differences in construction between the tires; the 47 is inexplicably thicker that the others, and the 32 is suspected of using a low-performance long-wear-life tread compound.

This all being said, my experiences more or less line up with BQ. The idea that a 32mm tire would be performing .6mph faster than a comparable 42mm tire strikes me as pretty bizarre, unless there are weird circumstances (i.e. the tires aren't actually constructed the same as each other, one of the tires has poor pressure configuration, Spoonrobot is a really speedy time trialist testing prototype 32mm aero rims for some reason, etc).

chas58

Agreed. Good points. Still, I’m not losing sleep over a couple of watts. 20-30 watts per tire might keep me up at night. ;-(


Yeah, but velodromes are so crazy fun. I'm doing good to cruise at 20mph on the road, maybe 15+ mph on dirt, but race on the velodrome around 35mph.

Seattle Forrest

I've been riding 28 mm tires for over a year, recently on rims that stretch them out to 32 mm. Very good size for unpaved roads around here. Deep gravel is pretty rare here, and who wants to ride that crap anyway?

HTupolev

Because:
High-performance road tires seem to perform about the same for me, regardless of width. I haven't tested this scientifically to the point of using tires of the exact same construction on the exact same bike. But for instance, on a relatively-flat ride I did many times last summer, I wasn't able to distinguish a performance difference between my Emonda ALR with its 23mm Bontrager R3s and my MTB drop-bar conversion with 53mm Rat Trap Pass ELs; both seemed to average just under 21mph around when I was in good shape.

While it's entirely possible that I'm missing something, a .6mph gap showing up between a 32mm tire and a 42mm tire of nominally similar construction would surprise me.

grolby

BQ's scientific testing happens to have led Jan Heine to the conclusion that the best-performing bicycle is a skinny round-tubed steel bike with 32-spoke wheels, box section rims, wide tires and non-aero brake levers. The last one is the real kicker for me - those old-school brake levers suck.

I don't think they're misrepresenting their findings, but those findings are different from pretty much everyone else engaged in performance testing. That should raise your eyebrows a bit.

chaadster

Yeah, Heine/BQ are interesting...in that way a lot of "old coots" are; they've got stories, they know some stuff, and you can pick up some gems if you're willing to sit around and wade through the asinine stuff that comes from the fact they're completely out of touch with the modern world.

Otherwise, I find these continual discussions of tire width rather droll, because isn't it obvious that the differences are rather small either way, and a rider has to be either really humping it or really focusing on feel for tire width to register either way. I mean, maybe if you don't group ride you won't see it that way, but for those of us who do, it's obvious tire width is not the difference between the fast kids and the slower kids!

Personally, I run 30c on 18.1mm bsw rims which give an actual casing width of 32mm. My gravel rides always contain stretches of pavement which are as hotly contested, or as crucial to ride success (i.e. not going OTB) as the unpaved parts, so I tend to run fairly high pressure so that when I'm careening through that last big downhill left hand sweeper at +35mph, which transitions from dirt to pavement just before the turn-in, I can be sure to feel the contact patch and know how the tire is hooking up, or when making the final power dump for the final sprint up the closing climb, which is pavement, I'm not bobbing and slogging my way up.

But that's me, based on my weight, my goals, and how I ride. I have no illusions that my ride mates, all of whom are lighter and who most often best me at the end up the climb, are giving up anything by running 36c or 38c rubber as they do, and if they are, I'm happy for it, because it gives me a fighting chance!

chas58

Good point about BQ.

Context is important, and almost always overlooked.

There is the racing me. I’m doing 35-40mph at the velodrome for short races. Everything makes a little difference, and it all adds up. I would say that if I’m not training 3-5 days a week, aero equipment doesn’t make too much difference.

Then there is the regular me. Not to different from the average guy in good shape. For a ride of 20-100+ miles, I’m not going to do sustained efforts over 18mph. Really, for casual, non “club” rides, most of us are going to be doing 15-18mph most of the time, not more. Just look at strava. Most of the solo rides I see are 12-16mph avg. “Club” rides are a lot faster.

And, in those conditions, gravel conditions, audax conditions, just going out for a non-competitive ride conditions, Jan’s recommendations make a lot of sense. Aero isn’t your biggest source of resistance below 20mph. Below 15mph, aero gets trivial.

And yeah, the club rides, the competitive events – Aero makes a difference.

HTupolev

Not a very interesting "gambit." You offered your experiences, I emphasized that mine seemed to differ and explained.

shelbyfv

I've ridden the GravelKing 32s because that was the widest I could fit. Many of the other riders are on 29ers with much wider tires. Our "gravel" is clay roads with random sections of washouts and washovers of loose stuff. Also creek crossings with gravel in the beds. On flats and climbs, my relative speed was faster than expected. On descents and creek crossings, the 32s sucked and I was painfully slow. If I had better handling skills and was comfortable with the bike sliding around, of course the descents could have been faster. Since even nice tires are not a budget breaker, no reason not to try wider if they fit.

09box

I've run 700x38s in gravel with no issues (except slipping traction going uphill). Otherwise, I run 700x32's on gravel and rough stuff with no issues.

Metieval

Interesting Topic, very!
I have a 2013 alloy synapse, I also have a trek Crossrip. I have found the synapse to be more comfortable on a 25c at 90 psi than the trek crossrip on a 40c MSO at 45 psi. this is just from hitting frost cracks in pavement.
So much for the tire and psi stuff for the comfort argument huh? Anyways I replaced the Synapse with a hi-mod supersix and it is win/win/win.

So why am I here reading the 32c gravel topic?

Both the Cannondale synapse and Trek crossrip are going away, but what bike do I buy to replace the synapse/crossrip with?

The new 2018 synapse will fit a 32c tire. Like the new WTB 32c exposure. Around here (Ohio) that is probably fine. If I go out west, Montana, Idaho, etc... and go exploring... maybe I need to find a different bike option than can fit wider.

Edit I suppose I might have to do the n+1 and buy the 2018 synapse for year round (winter/commute) riding with fenders, and then also buy a niner RLT or Slate or something for wide tires.

u235

Today, on my normal 30 mile loop I do often. I had to go around a road crew patching holes which added about 45 seconds and I caught a red light at the wrong time for another 4.5 minutes.

scotch

I currently ride 36s. They're awesome on road and off.

09box

I've had no issues running 32s in gravel. Also find it to be the right size.

unterhausen

our gravel roads are maintained regularly, and that means that deep gravel is pretty common. I went from 30mm tires and 20 flats a year to tubeless 38mm tires and zero flats, and everything about them is a lot better. Much more secure on long, curvy downhills. I'm not even sure there is a measurable increase in rolling resistance. We have some roads that the forest service calls "jeep trails" and my tires can go faster than my willingness to bounce my brain around on that stuff.

chas58

I use 32 in the summer and 40 in the winter/spring when roads are in rougher shape (and I’m not in as good shape either, LOL).
Last weekend I got lazy and left the 32mm on the rear and used the 40mm on the front for my gravel grinding. Mostly it is determined by the tire pressure I want to use.

I just bought some tires for my GF’s bike. They were a lot bigger than what I wanted but they were on sale. I ended up with 60mm Schwalbe G-One tires. A lot bigger than I wanted.

But, these tires rock! They have less rolling resistance than ANYTHING Schwalbe makes. They are on a crappy bike, but on level ground, asphalt, gravel, etc at 10-15mph, they are super fast. They are heavy compared to the tires I use, and the bike itself can’t climb, but the tires make it a rocket otherwise. I took them on mountain bike group ride, and on the non technical parts of the ride, I was having a hard time riding slow enough to keep pace with the group. :-O

I’m having a hard time taking the GF’s heavy bike (wheels, tires) on my normal long gravel rides, but I’m looking forward to playing with them on paths where the bike itself isn’t a handicap.

I’m just shocked how fast a 60mm tire can be. I'm still going to go for the light weight (bike/wheel/tire) option on anything that requires acceleration or climbing (for now at least).

JonathanGennick 

I bet they're fun too. Sounds like Schwalbe has a winner.

I rock a set of 47 mm Horizons from WTB. I'm a little overweight, and the wider tires let me run a comfortably low pressure. I can speed up going into rough sections. Their width gives me comfort and options, and a super-stable feeling when cornering.

Abe_Froman

Wait, what? There can't be that much of a speed difference due to rolling resistance on the wood floor..

chas58

Well the races are much shorter, mostly sprints. our team relays average about 33mph. Part of it is the incredibly smooth track, part of it is the bike (light, stiff, aero, with very fast tires), part of it is the competition, part of it is a very very tight pace line (where I can wiggle my elbows and touch the guy next to me). Riding solo I can probably get an extra 5mph apples to apples (say an hour long time trial). But the short races are very very fast.

Abe_Froman

Ahhh. Now THAT makes sense lol.

Sullalto

You really need a power meter and a lot of data(or some rigorous testing) to compare the two.

I know personally I tend to fall into a certain cadence and take things at a certain speed unless I'm actively pushing myself out of my routine. So I tend to be timed the same on all bikes, but how much effort that takes? Variable.