Move to 28c or not?

dstev55

I took my summer bike out yesterday. I wouldn't normally take it out this early in the year, especially with the amount of crap on the road at the moment but it has just had a fair bit of work done on it and I have a really hilly sportive next Sunday so I needed to test it before then. (Which I'm glad I did as I kept throwing the chain off the big front ring).

Anyway, I couldn't help but notice how much more uncomfortable it was than my winter bike. My summer bike is a Bianchi Infinito CV with 40mm deep and 27mm wide carbon clinchers on 25mm tyres whereas my winter bike is a Planet X London Road on shallower, though wide cheap and nasty aluminium rims but 28mm tyres.

You would automatically expect the Bianchi to be the comfier bike but it is not. It's not outright uncomfortable by any means but does not have the plush feeling of the Planet X.

Do you think the 28mm tyres make all that much difference?

I am looking at some new tyres for my Bianchi soon and I quite fancy the Pirelli Pzero Velo's but do I go for 25mm or 28mm? My frame will take 28's. Will that extra size and weight be detrimental to my bikes climbing ability? Really scratching my head on what to go for on this one.

veronese68

dstev55 wrote:

Will that extra size and weight be detrimental to my bikes climbing ability?

How much is the difference in weight? Do you climb much faster when you've just had a wee? That's probably more of a weight difference. The extra grip may give you more confidence downhill.

lostboysaint

Do it. Went from Michelin Pro Endurance 25c on the Wilier to Pro Endurance 28 on the Agree (bigger clearances) and it's worked a treat. Slightly lower pressures, bigger footprint when cornering, more comfort. Lovely

imposter2.0

dstev55 wrote:

Anyway, I couldn't help but notice how much more uncomfortable it was than my winter bike. My summer bike is a Bianchi Infinito CV with 40mm deep and 27mm wide carbon clinchers on 25mm tyres whereas my winter bike is a Planet X London Road on shallower, though wide cheap and nasty aluminium rims but 28mm tyres.

You've left out a critical part of the equation - ie the comparitive tyre pressures.

dabber

It's a comparison I'm interesting in testing for myself. My "best bike" is a Wilier Cento Uno which I'm currently running on Michelin Pro Endurance 23s (will try out 25s once I need replacements).
I recently went into fully comfort mode and got a Specialized Roubaix Comp which apart from Future Shock is running on Specialized Turbo Pro 28s. Very smooth, very comfortable and doesn't seem at all sluggish.
I haven't ridden the Wilier over the winter period, just the Roubaix since Christmas + a load of turbo work.
Next week I'm off to France for a few weeks and will take both the Wilier and the Specialized and will get a chance to test both on some decent climbs.

graeme_s-2

Having ridden my own PX LR and my Cannondale Slate a fair bit recently, I'd generally want to fit as wide a tyre as a frame will take these days. Why are you running skinny 28s on your London Road? If you're enjoying the comfort of those you should try it with some 38C Hyper Voyagers

dstev55

Graeme_S wrote:

Having ridden my own PX LR and my Cannondale Slate a fair bit recently, I'd generally want to fit as wide a tyre as a frame will take these days. Why are you running skinny 28s on your London Road? If you're enjoying the comfort of those you should try it with some 38C Hyper Voyagers

Because I've got a group of clubmates running 25's that I need to keep up with!

dstev55

Imposter wrote:

dstev55 wrote:

Anyway, I couldn't help but notice how much more uncomfortable it was than my winter bike. My summer bike is a Bianchi Infinito CV with 40mm deep and 27mm wide carbon clinchers on 25mm tyres whereas my winter bike is a Planet X London Road on shallower, though wide cheap and nasty aluminium rims but 28mm tyres.

You've left out a critical part of the equation - ie the comparitive tyre pressures.

I run the 25's at about 90 psi and the 28's at 80 psi.

dstev55

Veronese68 wrote:

dstev55 wrote:

Will that extra size and weight be detrimental to my bikes climbing ability?

How much is the difference in weight? Do you climb much faster when you've just had a wee? That's probably more of a weight difference. The extra grip may give you more confidence downhill.

Fair point but we all know the rotating weight of a tyre is going to have more of an effect than the same weight on myself or on other parts of the bike.

graeme_s-2

dstev55 wrote:

Graeme_S wrote:

Having ridden my own PX LR and my Cannondale Slate a fair bit recently, I'd generally want to fit as wide a tyre as a frame will take these days. Why are you running skinny 28s on your London Road? If you're enjoying the comfort of those you should try it with some 38C Hyper Voyagers

Because I've got a group of clubmates running 25's that I need to keep up with!

I've done a 70 mile hillyish sportive on mine on 37s. I did a group ride a couple of weeks back on my Slate. I'm really not convinced wider tyres are slower than skinny tyres.

https://janheine.wordpress.com/2018/01/ ... re-slower/

imposter2.0

dstev55 wrote:

Imposter wrote:

dstev55 wrote:

Anyway, I couldn't help but notice how much more uncomfortable it was than my winter bike. My summer bike is a Bianchi Infinito CV with 40mm deep and 27mm wide carbon clinchers on 25mm tyres whereas my winter bike is a Planet X London Road on shallower, though wide cheap and nasty aluminium rims but 28mm tyres.

You've left out a critical part of the equation - ie the comparitive tyre pressures.

I run the 25's at about 90 psi and the 28's at 80 psi.

Depending on your weight, those are pretty high pressures. You could potentially drop at least 10psi on both sets..

drlodge

dstev55 wrote:

Imposter wrote:

I run the 25's at about 90 psi and the 28's at 80 psi.

Move to tubeless and you can go lower, on 23c I'm running 90 on the rear and 80 on the front.

fenix

I'd definitely go to 28.

My summer bike is on 25mm - that's the widest I can fit.

My winter bike is a cross bike with full guards and 38mm Marathon tyres on. It's definitely slower than the summer bike but I think you need the width for the crappy roads.

My next summer bike will have to have clearances for bigger tyres - I can't see that a 28mm will slow you down measurably.

lettingthedaysgoby

Do it. They will be far more comfortable, give you more grip in corners and will make zero difference to your speed up hills.

veronese68

dstev55 wrote:

Veronese68 wrote:

dstev55 wrote:

Will that extra size and weight be detrimental to my bikes climbing ability?

How much is the difference in weight? Do you climb much faster when you've just had a wee? That's probably more of a weight difference. The extra grip may give you more confidence downhill.

Fair point but we all know the rotating weight of a tyre is going to have more of an effect than the same weight on myself or on other parts of the bike.

We think we know

In 2001 bike engineer Kraig Willett analysed the forces on wheels and concluded:

“When evaluating wheel performance, wheel aerodynamics are the most important, distantly followed by wheel mass. Wheel inertia effects in all cases are so small that they are arguably insignificant.”

The idea that rotating mass is important comes from the belief that wheel inertia matters, because it’s inertia that has to be overcome to accelerate a wheel. But Willett clearly demonstrates that wheel inertia doesn’t matter, so rotating weight is also relatively unimportant.

Why not? Well, you don't do much accelerating when you ride a bike, and even when you do the acceleration is relatively low, so the power expended accelerating a bike with ‘heavy’ wheels is only fractionally higher than that needed for light wheels. Overall weight matters when you’re climbing, but even that’s not as big a factor as people imagine and it’s a lot cheaper to save weight off your middle than the bike.

Wheel weight does make more of a difference if something has suspension as less unsprung weight enables the suspension to work better so a wheel can stay in contact with the ground better, improving grip. This does not apply to road bikes.

yiannism

I have also the infinito CV, going from vittoria Zaffiro 25mm pro slick to conti GP 4000S II 25mm made huge deference in comfort, and given that i am pretty heavy rider (83kg) i am using 110psi on the rear and 100 in front.

fenix

Oi !

I'm about that weight too. I'd not be anywhere near those PSI's. Even at 23mm I only use about 90.

graeme_s-2

I'm almost exactly that weight - even when I was heavier and running 23C tyres I didn't run them as high as that. There's just no need.

dstev55

Ok so I've ordered some Vittoria Corsa G+ 28's. Since ordering I've read they can come up much larger (well the 25's can so assume the 28's do too) so I hope they fit in my frame! The next thing - latex tubes or don't even go there?

joe_totale-2

dstev55 wrote:

Ok so I've ordered some Vittoria Corsa G+ 28's. Since ordering I've read they can come up much larger (well the 25's can so assume the 28's do too) so I hope they fit in my frame! The next thing - latex tubes or don't even go there?

I'm a fan of latex tubes, they definitely make a for a smoother ride.
I've never had any problem with installing them, I think the people who have had issues are the ones who are rushing and don't take their time to do it properly.

They do lose air from day to day so don't use them if the bike is used for daily commuting but for the weekly club ride bike they're worth it and frankly it's good practice to check your tyres before each of those rides.

dstev55

Joe Totale wrote:

dstev55 wrote:

Ok so I've ordered some Vittoria Corsa G+ 28's. Since ordering I've read they can come up much larger (well the 25's can so assume the 28's do too) so I hope they fit in my frame! The next thing - latex tubes or don't even go there?

I'm a fan of latex tubes, they definitely make a for a smoother ride.
I've never had any problem with installing them, I think the people who have had issues are the ones who are rushing and don't take their time to do it properly.

They do lose air from day to day so don't use them if the bike is used for daily commuting but for the weekly club ride bike they're worth it and frankly it's good practice to check your tyres before each of those rides.

Thanks, like you i think it's good practice to check air pressures before a ride anyway. My only other slight concern is that they'll be going on carbon rims with rim brakes. I'm not particularly hard on my brakes but I'm often in the Peak District so inevitably there'll be a fair bit of braking going on at times and I don't want any heat build up issues.

kingdav

dstev55 wrote:

I have a really hilly sportive next Sunday so I needed to test it before then. (Which I'm glad I did as I kept throwing the chain off the big front ring).

You doing the Burgess Hill Springtime Classic?

meursault

I've got 28mm Vittoria G+ on my Cannondale Synapse, and feels smoother than the 25mm Conti 4 seasons on my alu Boardman. I have had pressures at 95 back and 90 front for 28's and 100 back 95 front 25's. I didn't realise I could go even lower. I am 5' 10" 12.5 stone.

lostboysaint

I run my 28s at those pressures (less on the front actually!) and I'm much taller and heavier than you. You can go a long way lower than that.

lettingthedaysgoby

I’m 11.5 stone and run 75 front, 80 rear on 28mm GP4000’s.

ryan_w-2

I’m a fatty tyre convert.
Running 38c slicks @ 40PSI on my CX bike and find it no more effort than my S5 under 40km/h.

I have 25c GP4Ks on my S5 and run them at 95F / 100R @ 86kg BW.

I’d 100% run 28s on the S5 if they'd fit.

kingdav

kingdav wrote:

dstev55 wrote:

I have a really hilly sportive next Sunday so I needed to test it before then. (Which I'm glad I did as I kept throwing the chain off the big front ring).

You doing the Burgess Hill Springtime Classic?

Now postponed anyway due to the weather forecast.

dstev55

kingdav wrote:

kingdav wrote:

dstev55 wrote:

I have a really hilly sportive next Sunday so I needed to test it before then. (Which I'm glad I did as I kept throwing the chain off the big front ring).

You doing the Burgess Hill Springtime Classic?

Now postponed anyway due to the weather forecast.

Same as the Battle of Bradfield :roll:

That's 2 of out 2 postponed this year for me.

dstev55

Fitted the Vittoria Corsa G+ 28's to my Infinito CV. They measure around 28mm (with an old skool tape measure) on my Vision Metron 40's which I'm quite surprised about as there are reports that the 25's measure more like 27-28. By contrast they are only slightly wider than the 26mm Specialized S Works Turbo's that were already on it and they match the wheels really well. They both weighed 270g and the Specialized tyres weighed 210g and 220g although they were quite worn. Still a bit fair bit of clearance all round, the tightest area being under the front brake (Campag Super Record) but still a couple of mm spare.

I'm going to give them a go with standard butyl tubes before switching to Latex to see if I notice any difference. That way I've got a 3 way comparison.

froze

since we don't know your weight you can go to this site http://www.dorkypantsr.us/bike-tire-pre ... lator.html scroll down to the second calcuator, enter the total weight of your bike and you both ready to ride, enter your tire size and you will be shown what psi is idea give or take 5 psi. With wider 28mm tires you don't need as much pressure, if you play with the tire size on the calculator you will see this, the less tire pressure the more comfortable of a ride you will experience so those 28's will ride better then 23's.

dstev55

froze wrote:

since we don't know your weight you can go to this site http://www.dorkypantsr.us/bike-tire-pre ... lator.html scroll down to the second calcuator, enter the total weight of your bike and you both ready to ride, enter your tire size and you will be shown what psi is idea give or take 5 psi. With wider 28mm tires you don't need as much pressure, if you play with the tire size on the calculator you will see this, the less tire pressure the more comfortable of a ride you will experience so those 28's will ride better then 23's.

58 psi on a 25mm front with a 40/60 F/R distribution. Total weight 175lb. Really? Not convinced by that myself.

It says 51 front and 78 for the rear on 28s. That's too much of a gap for my liking. Quite happy to try 70 front and 78 on the rear though.