Roller with two different bikes

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

Quoted message said:

I recently bought rollers and am enjoying them...but here's the question

When I ride with Bike A., my speed at the same exertion (measured by HRM) as when I ride Bike B
is about 5mph slower. Bike A has Rolf Seistre

wheels

Quoted message said:

(with new and recently rebuilt freewheel) and Conti 3000 GP tires whereas Bike B has Mavic SSC SL
wheels with Vittoria Corsa Evo tires. I switched the wheels and Bike gained a lot of the speed
with the Mavic/Corsa combo.

What fascinates me is why there would be such a large difference between

the

Quoted message said:

two wheel/tire combinations. Those of you with more experience, please enlighten me. Are there
other factors?

Are the freewheel's the same on both bikes? how 'bout the chainrings? Is the computer properly
calibrated for each wheelset? are the tires pumped up to the same presure on both bikes? a
combination of all these factors could make quite a big difference.

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

Quoted message said:

I recently bought rollers and am enjoying them...but here's the question

When I ride with Bike A., my speed at the same exertion (measured by HRM) as when I ride Bike B
is about 5mph slower. Bike A has Rolf Seistre

wheels

Quoted message said:

(with new and recently rebuilt freewheel) and Conti 3000 GP tires whereas Bike B has Mavic SSC SL
wheels with Vittoria Corsa Evo tires. I switched the wheels and Bike gained a lot of the speed
with the Mavic/Corsa combo.

What fascinates me is why there would be such a large difference between

the

Quoted message said:

two wheel/tire combinations. Those of you with more experience, please enlighten me. Are there
other factors?

I noticed a similar effect when changing tires half-way through the winter - the roller just ate
tires like there is no tomorrow.

I switched from Bontrager Select 700Cx25 (relatively soft rubber) to Conti Gatorskin 700x23C (much
harder rubber). With the Gatorskins I now have to use 2-steps lower gear than with the Bontragers.
As a side-effect the noise level went down significantly, too.

So the tires, width and rubber mix, make a significant difference.

Enjoy the monotony of staring at the TV while on the rollers :-)

Bengt-Olaf.

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

Quoted message said:

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

Quoted message said:

I recently bought rollers and am enjoying them...but here's the question

When I ride with Bike A., my speed at the same exertion (measured by

HRM)

Quoted message said:

Quoted message said:

as when I ride Bike B is about 5mph slower. Bike A has Rolf Seistre

wheels

Quoted message said:

(with new and recently rebuilt freewheel) and Conti 3000 GP tires

whereas

Quoted message said:

Quoted message said:

Bike B has Mavic SSC SL wheels with Vittoria Corsa Evo tires. I

switched

Quoted message said:

Quoted message said:

the wheels and Bike gained a lot of the speed with the Mavic/Corsa

combo.

Quoted message said:

Quoted message said:

What fascinates me is why there would be such a large difference between

the

Quoted message said:

two wheel/tire combinations. Those of you with more experience, please enlighten me. Are there
other factors?

Are the freewheel's the same on both bikes? how 'bout the chainrings? Is

the

Quoted message said:

computer properly calibrated for each wheelset? are the tires pumped up to the same presure on
both bikes? a combination of all these factors could make quite a big difference.

Even if you have accounted for all the above variables (and I'm sure there are a few others) I would
not be surprised to hear that the tire/wheel combination still makes an observable difference in
your effort required. I'm guessing that it's the tire, not the wheel, that accounts for most of the
difference. The deformation of the tires where they meet the drums is responsible for the resistance
you experience while ridding rollers. Therefore, a change in the tire can be looked at as being
similar to adjusting the resistance on a mag/fluid/air trainer. Of course, if you have an external
resistance device on your rollers (Kreitler rollers with a Killer Headwind, for example) the
relative effect of a tire change would be reduced.

--
Greg Estep

Greg Estep said:

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

Quoted message said:

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

Quoted message said:

I recently bought rollers and am enjoying them...but here's the question

When I ride with Bike A., my speed at the same exertion (measured by

HRM)

Quoted message said:

Quoted message said:

as when I ride Bike B is about 5mph slower. Bike A has Rolf Seistre

wheels

Quoted message said:

(with new and recently rebuilt freewheel) and Conti 3000 GP tires

whereas

Quoted message said:

Quoted message said:

Bike B has Mavic SSC SL wheels with Vittoria Corsa Evo tires. I

switched

Quoted message said:

Quoted message said:

the wheels and Bike gained a lot of the speed with the Mavic/Corsa

combo.

Quoted message said:

Quoted message said:

What fascinates me is why there would be such a large difference between

the

Quoted message said:

two wheel/tire combinations. Those of you with more experience, please enlighten me. Are there
other factors?

Are the freewheel's the same on both bikes? how 'bout the chainrings? Is

the

Quoted message said:

computer properly calibrated for each wheelset? are the tires pumped up to the same presure on
both bikes? a combination of all these factors could make quite a big difference.

Even if you have accounted for all the above variables (and I'm sure there are a few others) I
would not be surprised to hear that the tire/wheel combination still makes an observable difference
in your effort required. I'm guessing that it's the tire, not the wheel, that accounts for most of
the difference. The deformation of the tires where they meet the drums is responsible for the
resistance you experience while ridding rollers. Therefore, a change in the tire can be looked at
as being similar to adjusting the resistance on a mag/fluid/air trainer. Of course, if you have an
external resistance device on your rollers (Kreitler rollers with a Killer Headwind, for example)
the relative effect of a tire change would be reduced.

The aerodynamic drag from the spokes is quite large when on the rollers, probably about 25% of what
you get at the same speed on the road, somebody else can do the math if they want to. Given that
you'll probably be going faster on the rollers than on the road, spoke drag will become
increasingly significant. Rolling resistance is much higher on rollers than on the road, for
obvious reasons. If you want to experiment, swap the tyres from one set of wheels to the other so
that you can isolate these two effects. Also check your position on the two bikes, as postural
effects can have consequences on the rollers which are often cancelled or overridden by aerodynamic
effects on the road.

Kinky Cowboy*

*Batteries not included May contain traces of nuts Your milage may vary

Thanks all....I'll try the tire swap this weekend. The Mavic spokes are bladed vs the Rolf's round
ones so that's probably in there two.

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

Quoted message said:

I recently bought rollers and am enjoying them...but here's the question

When I ride with Bike A., my speed at the same exertion (measured by HRM) as when I ride Bike B
is about 5mph slower. Bike A has Rolf Seistre

wheels

Quoted message said:

(with new and recently rebuilt freewheel) and Conti 3000 GP tires whereas Bike B has Mavic SSC SL
wheels with Vittoria Corsa Evo tires. I switched the wheels and Bike gained a lot of the speed
with the Mavic/Corsa combo.

What fascinates me is why there would be such a large difference between

the

Quoted message said:

two wheel/tire combinations. Those of you with more experience, please enlighten me. Are there
other factors?

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

Quoted message said:

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

Quoted message said:

I recently bought rollers and am enjoying them...but here's the question

When I ride with Bike A., my speed at the same exertion (measured by

HRM)

Quoted message said:

Quoted message said:

as when I ride Bike B is about 5mph slower. Bike A has Rolf Seistre

wheels

Quoted message said:

(with new and recently rebuilt freewheel) and Conti 3000 GP tires

whereas

Quoted message said:

Quoted message said:

Bike B has Mavic SSC SL wheels with Vittoria Corsa Evo tires. I

switched

Quoted message said:

Quoted message said:

the wheels and Bike gained a lot of the speed with the Mavic/Corsa

combo.

Quoted message said:

Quoted message said:

What fascinates me is why there would be such a large difference between

the

Quoted message said:

two wheel/tire combinations. Those of you with more experience, please
enlighten me. Are there other factors?

I noticed a similar effect when changing tires half-way through the

winter -

Quoted message said:

the roller just ate tires like there is no tomorrow.

I switched from Bontrager Select 700Cx25 (relatively soft rubber) to Conti
Gatorskin 700x23C (much harder rubber). With the Gatorskins I now have to use
2-steps lower gear than with the Bontragers. As a side-effect the noise level
went down significantly, too.

So the tires, width and rubber mix, make a significant difference.

Enjoy the monotony of staring at the TV while on the rollers :-)

Bengt-Olaf.

Effect of computer calibration should be looked at, but aside from that, I also
vote for tires. Back when my six-small-drum American Classic rollers were fresh,
I used to marvel at how much easier it was to spin my tubular wheels with 22mm
Conti Sprinters than my clinchers with the 20mm tires that were in vogue those
days. On a lark I put some Avocet 28's on (which measured about 25mm in those
days) and the clinchers became about as easy to spin as the tubies, in spite of
being much heavier. Took them out on the road and found the same to be true
there. Haven't had skinny tires on my bike ever since. These days anything
smaller than a true 23 doesn't even get considered, and I'm only 140lbs and have
mostly smooth roads where I
live.