wider tyres:Less MPH

[XmisterIS]

I take it this is after you've changed the trip computer's tyre circumference. What 21 tyres are you using? The only ones I can find look like very lightweight tyres which aren't likely to survive the junk on road surfaces I ride on.

Yes, changed the trip (before my cycle computer broke!).

I'm using Schwalbe Ultremo R 21c - insanely lightweight and very fast!!

 

[Alun]

Knapdog, if you go for 28mm tyres make sure you have the clearances for them before you buy. I run 28mm Conti Ultra Gatorskins at 100 psi and would recommend them.

 

[Crankarm]

Knapdog stick with 25s. I have tried 28s and 23s on my tourer, too heavy and too unforgiving respectively, and now decided 25s are the best combination for touring. Although when I checked pressures a few weeks ago I was shocked to see I had fitted a 23C on the back. No wonder the ride is a tad harsh. I must have fitted it as I didn't have another 25C kicking around when the last one wore out and forgotten about it. Fine on smooth roads though. I have 23C on the front irrespective of the back. The 28s will have a larger rolling circumference and will give marginally increased comfort due to the increased thickness of side walls compared to 25C. They will also make your bike feel slightly less manouevrable and are of course slightly heavier depending on tyre you choose. My tyres have all been Specialised Armadillo All Condition Pro tyres 23, 25 and 28C. Will shortly be trying Vittoria Rubino Pros as I have these in 23C on my road bike and like them a lot.

Of course tyre pressure will greatly affect ride quality and comfort. Why not just reduce the tyre pressure by 10-15 psi? I wouldn't go below 100psi though as this makes the tyre too soft and means lots of wasted energy.

If you are touring with a heavy load and few spokes in your wheel on factory built wheels I would say go for 28C tyres as they will be more forgiving on your wheel. If you've a 32H or better a 36H hand built strong wheel then 25C will be fine on a touring wheel carrying weight as will 23C for smooth roads.

If riding rough surfaces I would use a minimum of 28C.

Oh and +1 Alun's post re clearance issues with mudguards as already stated 28C have a significantly larger rolling cicumference. You will also have to re-calibrate your cycling computer if you have one.

Hope this has been of help.

 

[knapdog]

Knapdog stick with 25s. I have tried 28s and 23s on my tourer, too heavy and too unforgiving respectively, and now decided 25s are the best combination for touring.Hope this has been of help.

Yes, Crankarm, your thoughtful reply has been of great help. Thanks, all of you!

 

[RedBike]

Presume, following your theory that all racing cyclists are using the wrong tyres.

Given two tyres (one 23mm, one 28mm) that weigh the same and are pumped up to the same pressure the 28mm tyre will roll quicker.

The trouble is 28mm tyres are nearly always heavier and are run at lower pressures than 23mm tyres. So in the real world there is a noticable weight penalty with using a 28mm tyres. This additional rotational mass is very significant when climbing or sprinting out of corners which is why for racing you often use 23mm tyres.

 

[l4dva]

I went from 32 to 25 and the difference was un believable!!

My 32's we specialized borough's and the new tyres are michellin krylions, so they are two very different tyres in terms of weight and tread paterns.

I used to run the 32's at 100psi and the max pressure's on the michellins are 109, which is what I run them at, so slighty higher pressure and much lighter in weight and a slick tread patern will deffinatly equal huge decress in roll resistance and increase in speed in my opinon!