Re: Science of cycling still largely mysterious

Frank Krygowski <frkrygow@sbcglobal.net> wrote:

On 5/25/2025 4:41 PM, Roger Merriman wrote:

AMuzi <am@yellowjersey.org> wrote:

On 5/25/2025 1:45 PM, Wolfgang Strobl wrote:

Am Wed, 21 May 2025 19:17:51 -0400 schrieb Frank Krygowski
<frkrygow@sbcglobal.net>:
 

On 5/21/2025 4:13 PM, Roger Merriman wrote:

zen cycle <funkmasterxx@hotmail.com> wrote:

 
A full suspension bike is far more efficient over rough terrain in terms
of speed and comfort.

 
I dimly recall an article in _Bicycling_ magazine (before it effectively
morphed into "Buycycling") that documented the measured increase in
downhill speed of a suspended bike compared to a rigid bike. At that
time, it was an unfamiliar concept.

 
Problem is, some people generalize the fact that a good suspension
increases downhill speed on some undergrounds to circumstances where one
or all of these preconditions do not apply.  Suspension adds weight and
converts some of the potential energy to heat. When riding downhill,
additional weight has essentially no disadvantage, it might even help.
On rough underground and at speeds where air resistance is the main
parameter, helping the rider to hold a better aerodynamic position has
more effect than that little bit of energy loss.
 
Almost nothing of all that applies while riding on reasonably flat
ground or uphill.  Some modern wider tires have lower rolling resistance
than narrow high pressure road tires of the old and offer enough
suspension for most roads that aren't not completely broken.
 

 

Indeed doesn’t take a particularly rough gravel road for my MTB suspension
and tyres to make it a faster bike, vs the Gravel bike be that my times on
Strava or unfortunate Gravel riders on the Ridgeway etc.

 

And in the past few years, many people have realized that it takes very
little roughness to make wider, cushier tires valuable for increasing
speed.

 
Not necessarily. In recent years, some wider tires have become better in
terms of rolling resistance at lower pressure and without compromising
puncture resistance. It's not that people have recognized something that
has always been the case. The wider the better doesn't apply, either.
The optimum has only shifted a little, again.
 
Roads degrading faster due to heavier vehicles might be a reason, too.
 

Bumping the rider about has serious energy costs.

 
Of course.
 

 
 
Offroad cyclists (I am not among them) tell me that for all
suspension's weight and sloppiness, they cannot brake or
turn with a wheel in midair so suspension is necessary for that.
 

Even on the flat ground suspension is well fast, I regularly pass Gravel
folks on the Ridgeway which is one of the older roads in the uk, it’s not
technical it’s essentially a gravel road, but the MTB just flows and isn’t
kicked about like the gravel bikes are.

 
I once knew a local guy, a club member, who closed down his bike shop to
become a full time professional bike tourist. He got a job with a large
bike touring company, where he spent the entire year riding, leading
paying customers on bike tours. This was in the late 1990s, IIRC.
 
On one trip the group he was leading was passing through our area.
Someone organized a club ride to meet up with them, so I got to see the
bike he had chosen for his job. It was unlike anything he used to ride
before. As I recall, it had undersized wheels (maybe 24 inch?) that were
very aero (trispoke, I think), an aero bar, and full suspension.

That was sort of the Moulton idea, had short travel eslatomers? And small
high pressure tyres is apparently a Gravel version though much like the
Brompton (sans suspension) i suspect it’s off road performance will be
fairly limited.

Roll over of bigger tyres seems to matter hence racing XC and DH MTB has
largely moved to the 29er size.

 
The aero benefits were easy to understand, but I think for long mileage
day after day, he learned that the benefits of not being as jostled by
bumps exceed the energy losses of suspension bits heating up.

I’m guess heating up was typo? As heat isn’t really a factor unless you’re
really pushing hard such as repeated DH runs or similar.

 
ISTM that would be one of those tradeoffs, depending on the smoothness
of the riding surface. But few roads are as smooth as we'd like.
 

Suspension be that within the tyre or active suspension is a boon, I notice
the difference on the commute between Old School roadie and it’s 28mm tyres
and the converted MTB rolling on 50mm tyres, the old MTB is a plush ride
and potholes etc can largely be ignored and those that I would I’d
absolutely avoid in a car! It’s a slow old beast but that’s down to its
relaxed position and weight.

The old school roadie I do need to be more active about potholes and so on,
it’s also a bit faster due to weight and position which also encourages
faster vs relaxed ride.

Aka I pick and choose the bike I think will be most useful for each day, so
last Friday I needed to cross some across London within a fairly short time
frame, public transport had no hope, and car would of been painful! So old
school roadie it was!

Roger Merriman