AnthonyG

The most important factor that makes ANY tire faster or even slower is, flexibility.
More flexible tires are faster. Less flexible tires are slower and this appiles to car and truck tires too. Not just bicycle tires.

When in motion under load you will see a flattened section at the bottom where it contacts the road and this is actually a "feature" of tire design and not a fault per-see. When in motion a tire has to "flex" into the flat spot and then flex out of it again. Tires that are more flexible flex in and out with less resistance. Also when it comes to small bumps on the road a flexible tire will deform easily for the bump and keep on going forwards where as a less flexible tire will try to push the wheel up over the bump so not only are flexible tires faster they are also more comfortable.

So, tires with supple high thread count carcasses and thin treads are the fastest and the most comfortable yet the trade off is tread life and puncture resistance. Narrow tires which athletes use are only faster when your going so fast that wind resistance becomes an issue.

32mm to 42mm tires or even wider can be plenty "fast" enough as long as they are flexible enough and your not trying to consistently travel at more than say 25mph (40 kph).

Myosmith

Bontrager AW3 comes in 25mm, 28mm and 32mm. Good all around mixed surface tire that will suffice for many unpaved surfaces.

kovacsa

I came across a video, from GCN that explains how the contact patch the tire makes with the road affects the rolling resistance. It seems that narrower isn't necessarily faster when you drop below a certain threshold, but above a certain threshold, speed does not increase with width. A while ago, I went from a 35mm to a 32mm of the same tire and noticed a speed increase. So based on what is demonstrated in the video about the contact patch and my own experience, its seems 28+/-mm might be the sweet spot for width for speed. I find it hard to believe that 37mm, 42mm can roll faster than a 28mm of the same tire.

AnthonyG

Not all tires are the same and construction of a tire is far more important than the size of the tire.
If its the same brand and construction of tire then they will be pretty much as fast as each other. The only advantage that the smaller tire has is less wind resistance as the speeds get higher. If your getting along at 20mph (32kph) then the impact will be very minimal.
If your roads are rough though then the bigger tire will be faster as it has more room to flex over bumps rather than having to rise over bumps.
Higher tire pressures don't always make for a faster ride as they don't deflect over bumps as well. Its about getting the deflection in the sweet spot for the weight of the rider.

ramzilla

Panaracer Pasela tires roll fast. So do Michelin Protek. Cheaper Continental tires always blow out too easy. But, the Gatorskins are OK. High end Schwalbe tires are awesome but, you gotta pay $ for them.

canklecat

Depends on the pavement/terrain. That's usually the disclaimer attached to any test or anecdotal evaluation of wide vs narrow tires. Lab tests for rolling resistance don't reflect real world conditions.

GCN also compared a road bike, cross or gravel bike, and mountain bike with flat bars and suspension fork, on a segment of cobbles in Europe. Both Matt and Simon found the MTB to be faster and more pleasant to ride... on the cobbles. Neither wanted to ride the MTB on the rest of the route with good pavement.

My 30 lb Univega hybrid with Conti Speed Rides is definitely faster than my road bikes with 700x23 and x25 tires on the really bad mile-long segments near my home, where the road crews have milled off the old asphalt down to the concrete substrate, leaving a ridiculously rough mess that's like riding cobbles.

But once I'm back on decent pavement the road bikes are faster, although that's due in part to the more aero drop bars and lighter weight.

Reminds me, I need to save some video of those rides. In video the differences are really apparent. With my road bikes, the camera's built in electronic vibration reduction can't gracefully cope with the jarring chattering vibration on that busted up pavement. In particular with the carbon fiber Trek 5900 and 700x23 I have to stand to pedal most of that route -- it's brain numbing trying to sit and pedal on that stuff. But the videos from the Univega cockpit with the fatter Conti Speed Rides looks pretty normal.

bcpriess

I have Specialized FastTraks and WTB Riddlers, about 50mm or 2.0in, on my dropbar 26er, and they work well on most surfaces without slowing me down.

smashndash

https://www.bicyclerollingresistance...000-comparison

the #1 most important factor in going fast is tire construction. Don’t focus too much on width - a 23mm Kenda Kwest will get decimated by a 32mm GP5000. The #2 most important factor is setting the right pressure for the right conditions. If you’re light, and/or are riding on rough/loose terrain, you need to run at lower pressure. You can’t run a 23mm tire at 35psi without it getting floppy or pinching.

Get a fast, supple, slick tire that’s wide enough for your usage. Ideally something that isn’t too much wider than your rim. Even racers these days are running 28mm tires that measure over 30mm. So definitely bigger than that.

I’d personally recommend a 32mm race tire with sealant in the tubes. But a more durable variant on a race tire like the Pirelli Cinturato or the Vittoria Corsa Control might serve you better on rough terrain.

livedarklions

Is the 25 mph figure based on something or is it a guess? It doesn't sound unreasonable, but the stuff I have read hadn't figured out the point where the advantages of wider tires were outweighed by aero factors.You appear to be very knowledgeable on the subject, so I am wondering if you know of some data that supports the 25 mph factor.

I'm especially curious about this because I haven't noticed any significant difference between the 36s on my cyclo and the 28s on my hybrid-- I can stay well in the 30s on the downhills, and get above 25 on the flats (not for very long). What I have noticed is accelerating is easier on the 36s, but I am not sure if that's the bikes or the tires. Eventually, I'll try 36s on the hybrid and see.

grayrest

The 25mph number sounds like it's an educated guess to me. For aerodynamics, the top of the tire is the fastest moving part on the bike (it moves exactly twice the speed of the bike) and drag is area times velocity squared so the wider tire is going to be a noticeable drawback at some speed. Race motorcycles have a small fairing over the top of the front wheel to handle this and there's no reason you couldn't put one on a bicycle (e.g. front half of a close fitting full fender) but racers won't because fairings are banned by the UCI. I've done enough Jan Heine reading to be interested in what speed wide tires turn out to be a drawback and I know it is possible to get fairly accurate cda/crr numbers for a setup using the Chung method. It's on my list of things I want to try if I ever get a power meter.

For your 36 vs 28 example, it could be either the bike or the tires. Given the same bike and tire line, the wider ones should be slower accelerating due to the extra weight but I expect that'd be a smaller effect than the differences between bikes or tire manufacturers.

AnthonyG

Yes, the 25mph figure is an educated guess. I know that the reason for the narrower tires for racing is for the aerodynamic advantage rather than rolling resistance given the same tire construction.
I remember years ago when 1" (25mm) tires were the norm for racing. I tried 22mm tires once and hated them. I was much faster on the chip seal roads that we raced on with the wider tires.
These days when I ride around at 20mph or less on a mtn style bike I don't notice any more resistance from good quality wide tires than I do from the 23mm tires on my road bike.

My point is that unless your trying to get along consistently at speeds of 25mph+ at least then there simply isn't enough wind resistance in your face to make a noticeable difference and even then you will still get a greater benefit from bending your elbows than you will from using tires that are a couple of mm narrower.

If you look on Schwalbe's website they rate the 50mm wide Big Apple tires as having less rolling resistance than the slightly narrower Marathon Plus tires. Construction trumps everything else.

livedarklions

If it was the tire line, the 28s should be faster, they're Schwalbe One vs. Marathon 36s. Thanks for the reply!

livedarklions

The advantage to wider tires at lower pressure is it minimizes the loss of energy to suspension, so the question is at what point the increase drag coefficient caused by the widening of the tire cancels out that energy preservation. I can say confidently that I haven't noticed a difference in drag between the 36s and 28s at speeds around 25, and on Monday with the help of a 10 mph tailwind, I was going 25+ on my 36s for about 10 miles. What I do notice at those speeds is just how much more pleasant the 36s feel, I'm not absorbing anywhere as many bump shocks, and I definitely don't need padded gloves to be comfortable.

I agree that below 25, the aero effect of the wider tire is too minimal to notice, and I appreciate your educated guess.

My understanding is that the rolling resistance tests don't really pick up the suspension losses effect, which is part of the reason that the misconception that narrower is faster rose. Is that wrong?

Thanks for the reply!

livedarklions

I just kind of skipped over this part in my first reply, but I do disagree with you a bit here. I think the very small increase in weight is more than offset by the greater efficiency due to decreased energy loss to suspension with the larger tires. When I first started riding on the 36s, I was shocked at how fast I could spin them up from, say, 15 to 28 mph, and starting up after a red light is easier as well.

AnthonyG

I'm not quite sure what you mean by "suspension losses effect".

A rock hard solid tire is very slow and this has always been known. A tiny bump sends you off the ground so your energy is wasted going vertical rather than horizontal and when your wheel is off the ground the cranks just spin without pushing you forwards.

Its the ease at which a tire flexes into the flat contact patch, flexes over small bumps and then flexes back again that reduces rolling resistance and makes a tire fast. Any resistance from a tire to flexing generates some vertical force rather than horizontal force which is a complete waste of energy.

livedarklions

As I understand it, the lab resistance tests are done by running the unweighted wheel on a barrel and what they miss is the energy costs of bouncing a rider (weight) off the ground, so the lab tests grossly underestimate the energy advantages of the wider tires.

I'm not a tech person--am I getting this wrong?

xroadcharlie

Actually the tire you have don't look half bad if you're replacing them with tires about the same size. I'd go wider, Minimum of 38mm. Otherwise there may be little room for improvement. When it comes time to replace them that would be a good time to look at better tires.

livedarklions is correct about the misconception that large tires of the same design slow you down, At least to about 2". This misconception may come from a small difference in the rate of acceleration of a lighter tire. The peddle effort required to turn a heavier tire will be slightly higher then the light one, But that extra weight with puncture protection acts like a flywheel to maintain more speed at top stroke. It's only when we do an acceleration test on a stand there is a big difference. Not under load.

Even with the small knobs on many Schwalbe tires, to my surprise they are still quite fast, and the MUCH better traction off road is worth any small difference in speed on pavement vs their slick designs for an all round tire.

AnthonyG

Sorry, I can't comment on this aspect as I don't know the answer.
Getting the absolute best performance out of a tire is about getting just the right amount of sag at the bottom under load. Heavier people need higher air pressure's. Lighter people need lower pressure's.

bruce19

I think there are different ways of conducting lab tests. Some include rough surfaces for example. Pretty sure there's a GCN vid. that speaks to this.