Bring on the fat(ter) tyres

[vosadrian]

The gist of the pod cast is that a supple, fatter tyre is no slower that a supple narrow tyre. It's just that the wider tyre will provide you with more comfort and grip on rough/wet roads.

So a 23mm tyre is not slower than a fatter tyre, and if suppleness/rough/wet is not an issue than no real reason to change?

[Comedian]

So I listened to this podcast and found it absolutely fascinating. I had read in the past about how vibration affects power output so listening to these guys was a real lightbulb moment. The concept of it being a loose-loose in the middle ground too I found fascinating. The concept of having not enough pressure to get the low rolling resistance - but too much to get the smoother ride so incurring vibration losses was just fascinating.

I run 22/24mm tyres (conti force and attack) now so I thought I'd give it a go. I used to run 120 in both for races and probably 110r100f normally. I'm about 80kg. So I started dropping them.

I found that at 70r60f the ride was just beautiful. The bike felt just awesome. It didn't feel loose - it felt "chubby grippy" in mountain bike terms. Unfortunately the pressure wasn't enough for riding over lips in the curbing.

I then upped it to 80/80 and that was better. It felt good (but not quite as good). The pinchflat risk was better but still just there.

So, I've gone to 90/90. I think there is still a remote pinch flat risk but it's manageable. I think this is probably the realistic minimum for those tyres. This has proven to me that you'll pinch flat before the bike gets loose as you lower pressures.

Next experiment is for some bigger tyres.

[silentC]

[richard.allan]

That's an interesting video. I need a set of those wheels now!

[misterhorsey]

This being the case, would not thin tyres and high pressure be fastest on smooth roads, and fat tyres with less pressure on bumpy roads (chip gravel/dead road), and there would be some crossover in the middle.

We get close to smooth roads at an indoor velodrome. White lines on fresh hot mix come close, too.

You would dare to question the opiniin of the infallible Jan Heine?You should be burned at the stake.

Actually, if you read/listen to what Jann says, you'll find he agrees with vosadrian. He has provided a fair bit of data about the where and when of the cross over points too.

It's when people (like me ) turn it into a dogma ("the fattest tyre that will fit") that the nuances get lost.

I didn't read the source, but it makes sense to me. About half my riding is on pretty smooth roads and the other on pretty ordinary road including some pretty dead chip gravel roads. Most of the bad roads are in bunch rides, so not too fussed to lose a few Watts on a non-ideal surface when I have no problem staying with the bunch anyway.

I have never actually tried wider tyres. I have had people tell me how good they are, but I never noticed them suddenly get faster or slower. They tell me how much smoother it is, but I have no issue with how smooth my setup is so no need to try. Most of my wheels seem to be designed for 23s so I use 23s. I am sure there are some aero considerations using wider tyres on aero wheels that are not specifically designed for wider tyres. Swissside do a lot of aero testing of wheels and they seem to recommend Conti GP4k 23s as the ideal tyre for their wheels.

I suggest you have a listen to the podcast. My paraphrasing above was a bit of the gist from someone significantly removed from any evidence based analysis. Much better to listen to some people who've spent some time thinking and researching the topic rather than debating with relatively ill informed people such as myself. I found it a great post ride mortuary pose slumber listen when my body can't do anything and I'm too tired to sleep!

One thing that I took from the podcast is that 'smooth roads' aren't really as smooth as you'd think. Velodromes are ideal conditions not often found in the real world.

But there's also two things here. One's perception of efficacy of a particular tyre and pressure choice based on individual empirical experience is going to be pretty compelling. However, it's also worth trying to step outside your own perspective to attempt to objectively measure the performance of different tyre and pressure variables under controlled conditions.

As you say, you've never tried fatter tyres. You've no reason to doubt your current set up. But you may well find a different set up to be beneficial and you'll be wondering why you persisted for so long with a skinny set up. Or not.

[Comedian]

And continental update the Force/Attack combo to 23/25!

http://www.bikerumor.com/2016/10/28/con ... ires-more/

[singlespeedscott]

The gist of the pod cast is that a supple, fatter tyre is no slower that a supple narrow tyre. It's just that the wider tyre will provide you with more comfort and grip on rough/wet roads.

So a 23mm tyre is not slower than a fatter tyre, and if suppleness/rough/wet is not an issue than no real reason to change?

Yes. A supple 23mm tyre and a 30mm tyre both run at an ideal pressure are going to roll with the same resistance. The difference is going to be in grip and comfort, obviously in the fatter tyres favor.

If your road surface is pure hot mix with no lumps ( I wish I lived where you do) and you don't corner aggressively, a 23mm tyre would be fine.

[misterhorsey]

The gist of the podcast actually is that a fatter tyre at lower psi is faster than a skinnier tyre at higher psi. Not that it is no slower.

For the reasons discussed extensively in the podcast.

From the introductory blurb to the podcast:

Can’t quite allow yourself to believe that a 30mm tire at 70psi might be faster than a 23mm one at 100psi? Okay, but do yourself a favor and have a listen to what Poertner and Heine say about it — and keep an open mind, because what you feel, and what the numbers tell you, don’t always go hand in hand.

[Jash Rider]

Bought some Maxxis Re-fuse 28's on Friday and did my first ride this morning. Never going back to 23's again. The 28's are superior in every aspect. Better comfort, control, cornering and shock absorbing.

Interestingly the bike originally came with 28's, but I switched to 23's in the belief they'd be faster and more efficient. They're not. I doubt I'll buy 23's ever again.

[silentC]

I'm actually thinking of getting 28s. I only just bought a new rear tyre though, and it will be a year before I need new ones. I rode again with my mate on the 40's this morning. They don't seem to hold him back at all. I don't think I want to go quite that far though, they wouldn't fit my frame anyway.

[misterhorsey]

I actually ride 23s on my CAAD10 (now at 80psi, formerly 110psi), 25s on my Surly Cross Check (with pannier bags filled with groceries) now at around 90psi, and 28s on my kona paddywagon, generally at 80psi.

I can't honestly say there is a huge difference between any of them, other than that the surly is by far the most comfortable of all the bikes. And the CAAD10 is much, much, much more comfortable at lower pressures, and also seemingly with no performance drag (according to strava).

It does have me thinking that although aluminium frames get a lot of flak for a harsh ride, I wonder how much of this is because we have all been riding them with tyres inflated to give riders the sense of directness and harsh feedback, but at the expense of comfort and performance.

[Derny Driver]

If your road surface is pure hot mix with no lumps ( I wish I lived where you do) and you don't corner aggressively, a 23mm tyre would be fine.

Corner aggressively? I doubt anyone on this forum has ever pushed their tyres to the limit of grip. Having followed the Bank Race in the 90s every year (my dad was a mechanic) and watched the Pros ride insane crits around the streets of Nowra CBD, Hurstville and Canberra, then you'd know you dont need 2mm more grip. You just need some serious skills. Those blokes were probably on 21s too.

[Comedian]

So I've fitted some Conti 25's and am running them at 60f/70r and sublime...

I wonder if I can fit a 28 on...

[richard.allan]

I wonder if I can fit a 28 on...

Just remember the 28's are actually a bit wider than 28!

[Comedian]

I wonder if I can fit a 28 on...

Just remember the 28's are actually a bit wider than 28!

I think they will fit but the caliper clearance will be marginal.

However there is another bike in our fleet that can use them so if it doesn't work out then they have a home.

I think 28's might be at that point where the extra weight and aero drag is just past the point of being beneficial. Also the rims I have now are traditional width. I have wider rims and I need them back before I give it a go.

[singlespeedscott]

If your road surface is pure hot mix with no lumps ( I wish I lived where you do) and you don't corner aggressively, a 23mm tyre would be fine.

Corner aggressively? I doubt anyone on this forum has ever pushed their tyres to the limit of grip. Having followed the Bank Race in the 90s every year (my dad was a mechanic) and watched the Pros ride insane crits around the streets of Nowra CBD, Hurstville and Canberra, then you'd know you dont need 2mm more grip. You just need some serious skills. Those blokes were probably on 21s too.

23mm is so much better that all the pro's on 25mm tyres these days.

[Derny Driver]

23mm is so much better that all the pro's on 25mm tyres these days.

Pros ride whatever they are given, whatever Mavic or whoever are promoting. They dont get a choice. Try asking a pro rider how many psi are in their tyres and whether they run latex tubes and things like that and they will tell you to ask the mechanic. They dont know and they dont care. They are not paid to worry about stuff like that. They dont 'choose' their favourite tyres, they ride what they are given, like it or not.

But you've missed my point. Which is to call you out on your assertion that 23 mm tyres are not good enough to corner aggressively on. Which is rubbish. 25mm may be marginally better (I never said they were the same or worse) but in a crit a good rider on 23s would have no trouble at all disposing of a bunch of less skilled riders on 25s.

Like most things cycling, the equipment is not the biggest factor.

[Comedian]

Ok. So I did the experiment today. I bought a 28mm conti GP 4000. My intention was to try the rear only.

On the Lynskey the brake clearance is inadequate for the 28. On my traditional Fulcrum wheels it was like roll squeak... on the H Plus Son wheels it didn't touch but there was a bee's privates in it. I really don't think it's viable. Plenty of frame clearance though. I think if I changed the brakes to another design possibly but it's all getting hard...

On the Baum it was surprisingly a goer with both wheels. Ample frame clearance and the brake bar is a little higher so enough caliber clearance. I think I'd like to do some more testing. When I say adequate clearance there was 5mm. I think if you went off road there would be a chance of getting some muck up there. I think I need to think on that one - but I reckon it was a possibility. The wheels that are on it are optimised for 23 front and 25 rear so 25/28?? Maybe.

I tried both wheels with the 28 in a mates Cervelo R5. It had enough brake clearance but the frame at the BB was too tight. 25's were fine.

In other news it appears that Specialised have done a 26mm turbo. I think this is a good idea as there is a big jump from 25 to 28.

[TheWall]

Ok. So I did the experiment today. I bought a 28mm conti GP 4000. My intention was to try the rear only.

In other news it appears that Specialised have done a 26mm turbo. I think this is a good idea as there is a big jump from 25 to 28.

I ride the Turbo's and love them...I think they got tested as the fastest Clincher tyre somewhere...my Tarmac came with 24/24 but I am actually quicker (or less slow might be better!) on 26/26 but I think I will settle on the 24/26 as I believe it handles better.

Matt

[boyracer]

Been playing around with all sizes of tyres on my roadie after I accidentally put a 28mm conti commuter tyre on the rear of the Look once before a 100km bunch ride. Looked a bit like an ol' school hotrod...big n littles. i could notice the extra speed (put it down to circumference at the time). usually rode 25's F & R. 28 wouldn't go through the fork though.
Now fitted with challenge 27mm paris roubaix both ends (AT) 75/80psi. Sublime, but should be for the price!

[misterhorsey]

I actually ride 23s on my CAAD10 (now at 80psi, formerly 110psi), 25s on my Surly Cross Check (with pannier bags filled with groceries) now at around 90psi, and 28s on my kona paddywagon, generally at 80psi.

I can't honestly say there is a huge difference between any of them, other than that the surly is by far the most comfortable of all the bikes. And the CAAD10 is much, much, much more comfortable at lower pressures, and also seemingly with no performance drag (according to strava).

It does have me thinking that although aluminium frames get a lot of flak for a harsh ride, I wonder how much of this is because we have all been riding them with tyres inflated to give riders the sense of directness and harsh feedback, but at the expense of comfort and performance.

I"m now running the 25s (Conti Gatorskins, folding) on my surly at 70 psi. The ride is so smooth, so much more enjoyable. I can't say I notice any drop off in speed.

[madmacca]

Ok. So I did the experiment today. I bought a 28mm conti GP 4000. My intention was to try the rear only.

On the Lynskey the brake clearance is inadequate for the 28. On my traditional Fulcrum wheels it was like roll squeak... on the H Plus Son wheels it didn't touch but there was a bee's privates in it. I really don't think it's viable. Plenty of frame clearance though. I think if I changed the brakes to another design possibly but it's all getting hard...

I run 28mm conti GP 4000s. I have to deflate them to get them past the calipers (even with the brake release fully open), but no problems inflating once the wheel is installed.