Fat Tyres

For the last few years I have been trying out various sorts of fatter tyres, and have been increasingly pleased with what I've found.  I started with 30mm Schwalbe Marathon Racers for Paris Roubaix in 2014, and these worked very well.  Even for Paris Roubaix 30mm was pretty big in those days, and various disasters were forecast which didn't happen.  I changed to Schwalbe S-One 30mm for the Tour of Flanders in 2016, tubeless by now, and they were excellent. 

Testing the limits a bit, I used 40mm G-One gravel tyres, Schwalbe again, for the club Freewheel Competition in 2016.  They rolled better than anything else.  In the Spring of this year I rode the Hilly 50 on Compass 38mm tyres and came in third on the road.  And I'm an old man.  In July, I did the Dartmoor Ghost on Compass 44mm.  Perfect for the job - I did a good time.

So far so good.  But where is the limit for these things?  Would an infinitely large tyre be infinitely better?

Intuitively, the answer would seem to be no, and by experimentation I can confirm this.

The old Dawes tandem in the picture has 54mm tyres fitted.  It rolls much better with them, is very smooth, and the roads of Surrey appear to have been miraculously re-surfaced.  But, the Hill of Truth, Root Hill, reveals that a limit has been reached.  Tandems normally roll well, and this one does, but it wouldn't have won the Freewheel Competition.  It does very well, and I shan't be taking the tyres off, but it hasn't shown the performance gain that the smaller sizes have.

So, what have we learned?  Nowadays, everyone knows that fatter tyres are better.  The pros have started to use them, with 25mm or even 28mm being pretty common.  Their limits are set by the width of their brakes.  Discs will solve that problem and I think there will be more to come.

My suggestion would be that 30mm is where the benefits really start to show themselves.  If your bike will take them, fit tyres of at least this size.  The benefits generally seem to be a little greater between 30mm and 40mm.  Tyres larger than this give greater smoothness and much better capability on poor roads or tracks, but performance is starting to edge off again.

As a given, the tyres need to be light and of high quality.  Wall flexibility is particularly important.  They need to be run at low pressures - 40 psi does most things, you can go lower with fatter tyres.  If the tyres are tubeless - and most of them are - so much the better.

If you change to good quality tubeless tyres in the mid-30mm range your bike will roll better, be more comfortable on rough surfaces, grip better and suffer fewer punctures.

Mark