Road Bike, Cycling Forums banner
1 - 20 of 51 Posts

·
Registered
Joined
·
1,025 Posts
Discussion Starter · #1 ·
There has been increasing evidence that for road cycling, fatter tires run at lower pressures are actually faster than the traditional skinny/high pressure setup. Here's an interesting recent podcast on the topic:
CyclingTips Podcast, Episode 9: Rethinking road bike tire sizes and pressures | CyclingTips

In the podcast, the former technical director at Zipp and the publisher of Bicycling Quarterly describe how fatter, more compliant tires run at lower pressures actually reduce rolling resistance in real world conditions.

I've recently been putting this to the test. I weigh 155 lbs. I have a road/ gravel bike I've set up with slightly knobby Clement MSO 36mm tubeless tires that I've been running at 60 PSI. At relatively high speeds (23 mph+ group rides), the tires haven't been noticeably slower for me. They have been VASTLY more comfortable over bumps and chatter. As I'm not racing currently and I'm not noticing a significant slow down, the comfort benefit is a huge plus. At this point, I'm convinced of the benefits. I'll only buy road bikes that can fit bigger tires from now on. I'm also increasingly convinced of the benefit of tubeless: they simply ride better.

Have others had a similar experience?
 

·
Registered
Joined
·
9,658 Posts
I've recently been putting this to the test. I weigh 155 lbs. I have a road/ gravel bike I've set up with slightly knobby Clement MSO 36mm tubeless tires that I've been running at 60 PSI. At relatively high speeds (23 mph+ group rides), the tires haven't been noticeably slower for me.
Slower than what? Of course they'd likely be slower than a smaller tire if that smaller tires didn't have heavy tread and was a higher TPI.
 

·
A wheelist
Joined
·
11,324 Posts
I've recently been putting this to the test. I weigh 155 lbs. I have a road/ gravel bike I've set up with slightly knobby Clement MSO 36mm tubeless tires that I've been running at 60 PSI. At relatively high speeds (23 mph+ group rides), the tires haven't been noticeably slower for me.
A comparison based on nothing? :eek: What good is that and how can anyone comment; agree; refute?
 

·
Registered
Joined
·
65 Posts
That podcast was pretty convincing with the explanation for why higher pressures might feel faster, but now that we can precisely measure watts we can see that in most cases they aren't faster.

I've been tweaking my pressure downward a bit to see how it goes from my usual 100psi (25mm).
 

·
Banned Sock Puppet
Joined
·
14,411 Posts
Interesting. All I have to add is anecdotal information. I can't say I feel faster one way or the other. One thing I do know is that lower pressures increase the ride quality. All other things being equal, it's a no-brainer.
 

·
Registered
Joined
·
1,025 Posts
Discussion Starter · #6 ·
A comparison based on nothing? :eek: What good is that and how can anyone comment; agree; refute?
This seems unnecessarily harsh. My point here is not to provide "proof", it's to spark a discussion. I've had some anecdotal experiences and felt like sharing them. I wanted to see if others have as well.

What I'm saying is that I didn't ride noticeably slower at a perceived level of effort. Obviously this is anecdotal and far from scientific. If you listen to the podcast, pros have measured the effect precisely using power meters and controlled conditions and realized noticeable improvements by going lower / fatter.
 

·
'brifter' is f'ing stupid
Joined
·
15,563 Posts
Have others had a similar experience?
After reading post #4 I'm sure you'll think this is 'unnecessarily harsh' but...you're serious? This has been the subject of dozens of thread and hundreds of posts over the last, oh, I don't know, decade maybe? This is nothing new. The bicycle world has been discovering physics and it's benefits relating to tire size/inflation for a long time now.
 

·
A wheelist
Joined
·
11,324 Posts
This seems unnecessarily harsh. My point here is not to provide "proof", it's to spark a discussion. I've had some anecdotal experiences and felt like sharing them. I wanted to see if others have as well.

What I'm saying is that I didn't ride noticeably slower at a perceived level of effort. Obviously this is anecdotal and far from scientific. If you listen to the podcast, pros have measured the effect precisely using power meters and controlled conditions and realized noticeable improvements by going lower / fatter.
Ok, my "proof" when going from road bike with 25mm, 80/90 psi tires to my cx bike with 32mm cx knobbies at around (I forget) 50 psi was a continual drop of 1.5mph in my well-documented average speeds when I stuck just to paved rides on the cx bike. That, with a comparison, with data, is as un-anecdotal as I can get and it was certainly good enough for me to know that the cx bike, with cx tires was slower than a road bike with road tires.

I had two full summer seasons of riding, swapping back & forth between the two bikes, to know that the cx bike was slower.

Even without my "proof" it wouldn't be far flung to imagine that the cx bike was going to be slower than the road bike.
 

·
Registered
Joined
·
8,792 Posts
Ok, my "proof" when going from road bike with 25mm, 80/90 psi tires to my cx bike with 32mm cx knobbies at around (I forget) 50 psi was a continual drop of 1.5mph in my well-documented average speeds when I stuck just to paved rides on the cx bike. That, with a comparison, with data, is as un-anecdotal as I can get and it was certainly good enough for me to know that the cx bike, with cx tires was slower than a road bike with road tires.

I had two full summer seasons of riding, swapping back & forth between the two bikes, to know that the cx bike was slower.

Even without my "proof" it wouldn't be far flung to imagine that the cx bike was going to be slower than the road bike.
You're mixing bananas and apples here. Of course the knobbies are going to be slower, but put some 32/38mm, at around 50psi, road tires on that cross bike, and then compare.

You wouldn't compare your 25mm road tires to the 32mm knobbies by riding them in the mud, so why would you compare your knobbies to your road tires by riding them on the pavement. There are plenty of comparable 32+ mm tires out there, so why not get a set of those to use to offer your proof?
 

·
A wheelist
Joined
·
11,324 Posts
You're mixing bananas and apples here. Of course the knobbies are going to be slower, but put some 32/38mm, at around 50psi, road tires on that cross bike, and then compare.

You wouldn't compare your 25mm road tires to the 32mm knobbies by riding them in the mud, so why would you compare your knobbies to your road tires by riding them on the pavement. There are plenty of comparable 32+ mm tires out there, so why not get a set of those to use to offer your proof?
You missed the point of the OP's post. He said "fatter tires run at lower pressures are actually faster than the traditional skinny/high pressure setup." He then went on to talk about "36mm tubeless tires that I've been running at 60 PSI. At relatively high speeds (23 mph+ group rides), the tires haven't been noticeably slower for me." but he doesn't say what he's comparing them to. Road tires? Softer/harder knobbies?

Without this reference I took it to mean "road tires to cx tires" comparison. He did use the terms "fatter" and "skinny/high pressure". As I did say in my post "......the cx bike was going to be slower than the road bike."
 

·
Registered
Joined
·
5,380 Posts
I have noticed that with bigger tires, and lower pressures, my super moto bike is much faster than my road bike. I mean really faster, like maybe 70mph faster. So I'd go with lower pressures and bigger tires next time I order equipment.
 

·
Registered
Joined
·
416 Posts
I have noticed that with bigger tires, and lower pressures, my super moto bike is much faster than my road bike. I mean really faster, like maybe 70mph faster. So I'd go with lower pressures and bigger tires next time I order equipment.
best post of the day. lol
 

·
Registered
Joined
·
21,636 Posts
That podcast was pretty convincing with the explanation for why higher pressures might feel faster, but now that we can precisely measure watts we can see that in most cases they aren't faster.

I've been tweaking my pressure downward a bit to see how it goes from my usual 100psi (25mm).
And yes, there are several people on this board who have been saying exactly that for a decade or so. Jan Hein published data on this a long time ago (he's one of the guys on the podcast) but there are many who come here insisting that more pressure is faster. And to justify it they parrot exactly what was highlighted in the podcast - it "feels" faster. When you challenge them to employ a stopwatch, they don't want to hear it.
 

·
'brifter' is f'ing stupid
Joined
·
15,563 Posts
I have noticed that with bigger tires, and lower pressures, my super moto bike is much faster than my road bike. I mean really faster, like maybe 70mph faster. So I'd go with lower pressures and bigger tires next time I order equipment.
Super moto rules...



 

·
Banned Sock Puppet
Joined
·
14,411 Posts
You missed the point of the OP's post. He said "fatter tires run at lower pressures are actually faster than the traditional skinny/high pressure setup." He then went on to talk about "36mm tubeless tires that I've been running at 60 PSI. At relatively high speeds (23 mph+ group rides), the tires haven't been noticeably slower for me." but he doesn't say what he's comparing them to. Road tires? Softer/harder knobbies?

Without this reference I took it to mean "road tires to cx tires" comparison. He did use the terms "fatter" and "skinny/high pressure". As I did say in my post "......the cx bike was going to be slower than the road bike."

I have to disagree with your assumption here, Mike. My assumption was that the variables the OP did not mention did not change - slicks vs. knobbies. Of course knobbies will be slower than road slicks. This will make a big difference regardless of width or pressure.

And I would guess than your cx bike weighs a little more than your road bike.
 

·
Registered
Joined
·
9,658 Posts
I have to disagree with your assumption here, Mike. My assumption was that the variables the OP did not mention did not change - slicks vs. knobbies. Of course knobbies will be slower than road slicks. This will make a big difference regardless of width or pressure.

And I would guess than your cx bike weighs a little more than your road bike.
You missed the point, completely, in quite an ironic way.
 

·
Banned Sock Puppet
Joined
·
14,411 Posts

·
Registered
Joined
·
9,658 Posts
Apparently not.



Apparently so.

Could you guys elaborate? What am I missing?
Now that I re-read what he (Mike) said I see where you're coming from. I thought his point was that "lower" and "bigger" was kind of useless to say without saying what it's lower and bigger than because that seemed to be the point of his first response. But he made an assumption just like you. His assumption is probably a safer one because "smaller" tires are less likely to have knobby tread but still an assumption.
So I'll take my to you back.
 
1 - 20 of 51 Posts
Top