26 inch rolling resistance

Paul said:

I am in the process of choosing a bike, mainly for a longish commute (15
miles each way)but also for some light touring. The Thorn xtc appeals
because of its versatility, however I have concerns about the efficiency of
26inch wheels. Having done a bit of research on the net, I understand that
rolling resistance is linearly related to wheel diameter. However, what I
can't get my head around is how significant this is in the real world. Could
the difference in RR between 26inch and 700c be easily eliminated by
increasing tyre pressure or switching to 1inch slicks for example? Or is it
more significant than that.

My only experience to date has been of a 700c road bike. Would I notice the
difference by switching to 26inch? (all other things being equal - position,
drop bars, tyres etc).

Opionions/experiences much appreciated.

For a properly inflated, reasonably 'thin' tyre, the increase in rolling
resistance between these wheel sizes will be completely dwarfed at normal
cycling speeds by the many other factors having an effect.

Quoted message said:

Could the difference in RR between 26inch
and 700c be easily eliminated by increasing tyre pressure or switching
to 1inch slicks for example? Or is it more significant than that.

You'd have the same type of tyres and same pressure anyway, so you wouldn't
be able to make the difference up by changing tyres or pressure.

Paul said:

I am in the process of choosing a bike, mainly for a longish commute (15
miles each way)but also for some light touring. The Thorn xtc appeals
because of its versatility, however I have concerns about the efficiency of
26inch wheels. Having done a bit of research on the net, I understand that
rolling resistance is linearly related to wheel diameter. However, what I
can't get my head around is how significant this is in the real world. Could
the difference in RR between 26inch and 700c be easily eliminated by
increasing tyre pressure or switching to 1inch slicks for example? Or is it
more significant than that.

My only experience to date has been of a 700c road bike. Would I notice the
difference by switching to 26inch? (all other things being equal - position,
drop bars, tyres etc).

Opionions/experiences much appreciated.

I used to do 16 miles each way on a bike equipped with semi-slicks.
took about 50 mins (1hr 10 with two kids in the trailer.. This was an
MTB.

The rolling resistance comes from the energy required to deform and
reform the shape of the carcass as the wheel rolls. It may well be less
for larger wheels. Bear in mind though that the air resistance is
related to the cube of the speed and the cross sectional area, and in
the case of a wheel, the top edge is moving twice as fast as you are.
Smaller wheel then will go faster.
Smaller wheels are worse on bumpy roads.

In practice, for that distance on a regular basis, find a bike you like
riding and is comfortable. Don't worry about the speed.

YPYMATYC.

...d

Paul said:

I am in the process of choosing a bike, mainly for a longish commute (15
miles each way)but also for some light touring. The Thorn xtc appeals
because of its versatility, however I have concerns about the efficiency of
26inch wheels. Having done a bit of research on the net, I understand that
rolling resistance is linearly related to wheel diameter. However, what I
can't get my head around is how significant this is in the real world.

Bugger all, in real terms, or triathletes wouldn't race with 650 wheels,
serious racing 'bents would all have 700c wheels at the back rather than
the 26" the majority seem to use and the UCI wouldn't have banned small
wheel bikes in the wake of their being raced successfully. Note that a
Moulton holds a 200m sprint record, and speaking of Moultons, Dr M. did
lots of experiments with different sized wheels before settling on small
ones, which he did after finding they weren't nearly as big a
disadvantage as people imagine as long as they had good high pressure
tyres. A good roadgoing suspension helps too, but bottom line is a 26"
rolling resistance won't hurt you. Plus the wheels will be stronger and
you'll have a better range of more easily available tyres to choose from.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email hidden] http://www.dundee.ac.uk/~pjclinch/

Paul said:

I am in the process of choosing a bike, mainly for a longish commute (15
miles each way)but also for some light touring. The Thorn xtc appeals
because of its versatility, however I have concerns about the efficiency of
26inch wheels. Having done a bit of research on the net, I understand that
rolling resistance is linearly related to wheel diameter. However, what I
can't get my head around is how significant this is in the real world. Could
the difference in RR between 26inch and 700c be easily eliminated by
increasing tyre pressure or switching to 1inch slicks for example? Or is it
more significant than that.

You may notice that the 26" is a rougher ride, when you put a narrow
tyre on it. OTOH my judgment on this is probably not worth much as my
700C bike is a tandem and 26" a single.

James
--
James Annan
see web pages for email
http://www.ne.jp/asahi/julesandjames/home/
http://julesandjames.blogspot.com/

"James Annan" <[email hidden]> wrote in message
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Quoted message said:

Paul said:

I am in the process of choosing a bike, mainly for a longish commute (15
miles each way)but also for some light touring. The Thorn xtc appeals
because of its versatility, however I have concerns about the efficiency

of

Quoted message said:

Quoted message said:

26inch wheels. Having done a bit of research on the net, I understand

that

Quoted message said:

Quoted message said:

rolling resistance is linearly related to wheel diameter. However, what

I

Quoted message said:

Quoted message said:

can't get my head around is how significant this is in the real world.

Could

Quoted message said:

Quoted message said:

the difference in RR between 26inch and 700c be easily eliminated by
increasing tyre pressure or switching to 1inch slicks for example? Or is

it

Quoted message said:

Quoted message said:

more significant than that.

Thanks for all your replies and for putting it all in context. I'm starting
to think that I would be happy to live with a slight loss in
speed/efficiency for the sake of a more versatile/comfortable bike, so long
as the commute doesn't become a slog and I can keep up a reasonable average
speed.

Cheers

Paul

"Paul" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Thanks for all your replies and for putting it all in context. I'm
starting
to think that I would be happy to live with a slight loss in
speed/efficiency for the sake of a more versatile/comfortable bike, so
long
as the commute doesn't become a slog and I can keep up a reasonable
average
speed.

The only thing that I would say is that you can get narrower tyres for 700c
than you can for 26"/559 mtb wheels. My 700c with 23mm tyres bike rolls
more easily than my 26"/25mm bike and the difference in tyre profile looks
like more than 2mm. Tyre pressures are similar. But I can't say the
difference is just due to the tyres - it's all-round a much lighter bike.
Nevertheless I would be much happier if I could get tyres less than 25mm for
my 26" bike, and have even considered at times getting 650c wheels built up
just so I could put narrower tyres on them!

Rich

Paul twisted the electrons to say:

Quoted message said:

so long as the commute doesn't become a slog and I can keep up a
reasonable average speed.

Well, if my experience from last week is anything to go by you don't have
much to worry about. Someone on a MTB (ie: 26" wheels) latches onto the
(700c) rear wheel of my recumbent as I set off downhill from some traffic
lights. I hit ~25mph for most of the downhill section and then when I
slow up as the road levels out, said MTB passes me and disappears into
the distance ...

My defense is that I was at the end of a long ride, and was rather tired
y'honor.
--
These opinions might not even be mine ...
Let alone connected with my employer ...

For what it's worth, I was asking myself the same question why I bought
my Thorn Nomad. In the end I accepted Thorn's propagandathat 26" was
"better" for most purposes other than air-resistance at higher speeds
(over 20mph *average*, which is pretty fast - for me at least). I was a
bit skeptical, but the bike does roll along much better than my old
700c bike and is more comfortable. That said the Thorn's a hugely more
costly machine, so it's not a like-with-like comparison.

I do rather wish I'd gone for the XTC rather than the Nomad though - I
do go offroad, and I very occasionally carry lugage, but never both at
once - so could do with a pound or two less weight. That said, I've
taken the Nomad with its road wheels and tyres on some ridiculous
tracks and it's been great. I thin the Nomad was cheaper at the time
and I was already spending too much. They've since brought out the
Rollhoff bikes which would have been tempting. I've had a go on one and
it seemed a good system, although I believe there's some snag having
the Rollhoff with dropped bars for some reason.

Now wildly off the question, but I'm extremely pleased with my Thorn,
although some others here don't rate them. To be fair, I've not really
tried anything else in the same price-band.

Hywel

hyweldavies said:

Now wildly off the question, but I'm extremely pleased with my Thorn,
although some others here don't rate them.

I've only ever heard good opinions about Thorn bikes. Not
necessarily something that can be said about Robin Thorn, but
that's a separate issue!

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email hidden] http://www.dundee.ac.uk/~pjclinch/

Peter Clinch said:

hyweldavies said:

Now wildly off the question, but I'm extremely pleased with my Thorn,
although some others here don't rate them.

I've only ever heard good opinions about Thorn bikes. Not necessarily
something that can be said about Robin Thorn, but that's a separate issue!

I've been quite disappointed with mine, both in the finish and the ride.
It doesn't roll anything like as well as a bike with light 700c wheels.

"Peter Clinch" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

hyweldavies said:

Now wildly off the question, but I'm extremely pleased with my Thorn,
although some others here don't rate them.

I've only ever heard good opinions about Thorn bikes. Not
necessarily something that can be said about Robin Thorn, but
that's a separate issue!

Pete.
--

Well, I'll soon find out- just won a Thorn XTC on e-bay (ex-display from SJS
but never ridden). £500 less than list price! The only thing I'm worried
about is the reputedly poor paint job - well I suppose I could afford a
re-spray now..

Thanks for your opinions

Cheers

Paul

Paul said:

Well, I'll soon find out- just won a Thorn XTC on e-bay (ex-display from SJS
but never ridden). £500 less than list price! The only thing I'm worried
about is the reputedly poor paint job - well I suppose I could afford a
re-spray now..

They vary. The paint on my Nomad was *[censored]*. The paint on an XTC I've
seen was very good.