skinny tyres, fat tyres...

Since one of my luverly low-spoke-count wheels with skinny(ish) slicks fitted suddenly decided to
have one spoke less than it should have, I fitted an old 'ordinary ' wheel in the rear with a rather
fatter tyre in its place. I have to say I was stunned how much more comfortable a ride the fatter
tyre gives! Well, it was only the difference between 1.2" and 1.5" and about 20psi less pressure but
it was very noticeable. I don't seem to remember noticing such a difference going the other way.
What surprised me even more was that my time to work, despite getting slowed down in a couple of
places by some heavy traffic, was only 30 secs more than my best ever time. I'm not sure if it
wasn't because I was less concerned about potholes and speed bumps!

Makes me wonder whether there's really any point in narrow slicks on London's wonderful roads?

Rich

 

"Richard Goodman" <[email protected]> wrote in message
news:[email protected]...
> Since one of my luverly low-spoke-count wheels with skinny(ish) slicks fitted suddenly decided to
> have one spoke less than it should have, I
fitted
> an old 'ordinary ' wheel in the rear with a rather fatter tyre in its
place.
> I have to say I was stunned how much more comfortable a ride the fatter
tyre
> gives! Well, it was only the difference between 1.2" and 1.5" and about 20psi less pressure but it
> was very noticeable. I don't seem to remember noticing such a difference going the other way. What
> surprised me even
more
> was that my time to work, despite getting slowed down in a couple of
places
> by some heavy traffic, was only 30 secs more than my best ever time. I'm not sure if it wasn't
> because I was less concerned about potholes and
speed
> bumps!
>
> Makes me wonder whether there's really any point in narrow slicks on London's wonderful roads?
>
> Rich
>
>
In some cases fatter tyres can speed you up - fatter tyres can house their deformation in the upper
part of the tyre wall, where as for narrower ones it has to be at the bottom and so increases the
foot print. However this does depend on the pressure in the tyres - if you pump em up so that they
can hardly deform (noticeably) at all then the narrower one should have less foot print. How ever,
once up to speed the rolling resistance makes very little difference to speed compared to wind
resistance so I always go for the most comfortable tyres as the gain in comfort can far out weigh
any increased rolling resistance for general riding.

 

"Si Davies" <[email protected]> wrote in message
news:[email protected]...
>
> In some cases fatter tyres can speed you up - fatter tyres can house their deformation in the
> upper part of the tyre wall, where as for narrower ones it has to be at the bottom and so
> increases the foot print. However this does depend on the pressure in the tyres - if you pump em
> up so that they can hardly deform (noticeably) at all then the narrower one should have
less
> foot print. How ever, on up to speed the rolling resistance makes very little difference to speed
> compared to wind resistance so I always go for the
most
> comfortable tyres as the gain in comfort can far out weigh any increased rolling resistance for
> general riding.
>

Yes, I hadn't thought about that. Of course wind resistance is much more significant than rolling
resistance, and so many other factors can come into play to determine commuting times that one might
just as well go for the most comfortable tyres.

And just to emphasise the fact that yesterday wasn't a fluke, today I beat my best time to work by
over three minutes! A combination I think of good weather, absence of headwind (which there seemed
to be every day over winter), low traffic (London almost seems to have emptied for Easter already,
at least the parts of my route) - and, I feel convinced, something to do with the fatter tyre. The
bike seems less skitish over the bumps and I think I'm able to peddle harder because of that - I
suspect that with the thinner, harder tyre I tend to ease off and even stand slightly out of the
saddle when going over bumps, with the softer tyre I don't. Interesting.

Rich