Avid Rollamajig works with Campagnolo?

[Bruce W.1]

I'm doing some upgrades to my road touring bike. I ran across the Avid
Rollamajig. This device looks like very a good idea. But I'm left
wondering if it would thread into a recent Campagnolo rear derailleur
like, say, the Veloce.

Anybody have experience with this? Does it work well?

Thanks for your help.

[Mark Hickey]

"Bruce W.1" > wrote:

>I'm doing some upgrades to my road touring bike. I ran across the Avid
>Rollamajig. This device looks like very a good idea. But I'm left
>wondering if it would thread into a recent Campagnolo rear derailleur
>like, say, the Veloce.
>
>Anybody have experience with this? Does it work well?

'Smatter of fact, I happen to have a Rollamajig on a Veloce rear
derailleur on my own time trial bike. Works like a champ. I
installed it to reduce the cable friction (which is considerable since
the shifters are bar end shifters on the end of the aerobars, and are
a LONG way from the derailleurs).

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

[David Damerell]

begin quoting Mark Hickey >:
>'Smatter of fact, I happen to have a Rollamajig on a Veloce rear
>derailleur on my own time trial bike. Works like a champ. I
>installed it to reduce the cable friction (which is considerable since
>the shifters are bar end shifters on the end of the aerobars, and are
>a LONG way from the derailleurs).

Is that really necessary? I don't see 'em on tandems...
--
David Damerell > flcl?
Today is Thursday, January.

[gearoidmuar]

I use 2 of these to carry the cables from my STI shifters down, to avoid my
handlebar bag on a touring bike. Work great. Good idea this.

[Baird Webel]

In article >,
David Damerell > wrote:

> begin quoting Mark Hickey >:
> >'Smatter of fact, I happen to have a Rollamajig on a Veloce rear
> >derailleur on my own time trial bike. Works like a champ. I
> >installed it to reduce the cable friction (which is considerable since
> >the shifters are bar end shifters on the end of the aerobars, and are
> >a LONG way from the derailleurs).
>
> Is that really necessary? I don't see 'em on tandems...

Not absolutely necessary, but I use one on our tandem and am happy with
it.

Baird

[Mark Hickey]

David Damerell > wrote:

>begin quoting Mark Hickey >:
>>'Smatter of fact, I happen to have a Rollamajig on a Veloce rear
>>derailleur on my own time trial bike. Works like a champ. I
>>installed it to reduce the cable friction (which is considerable since
>>the shifters are bar end shifters on the end of the aerobars, and are
>>a LONG way from the derailleurs).
>
>Is that really necessary? I don't see 'em on tandems...

My time trial bike has a lot more cable housing than my tandem (which
really only has as much as a single bike, plus a coupe short pieces to
carry the cable around the eccentric bottom bracket).

It really did improve the shifting - keep in mind that not only is the
friction higher with all that extra cable, but the thumbie shifter
doesn't give nearly the leverage that a longer shifter would.

I eventually converted the shifters to Dura Ace which allow me to use
them in friction mode - that way I can shift any one of the several
mismatched rear wheels I want to throw on the bike.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

[Joe Riel]

Mark Hickey > writes:

> My time trial bike has a lot more cable housing than my tandem (which
> really only has as much as a single bike, plus a coupe short pieces to
> carry the cable around the eccentric bottom bracket).
>
> It really did improve the shifting - keep in mind that not only is the
> friction higher with all that extra cable, but the thumbie shifter
> doesn't give nearly the leverage that a longer shifter would.

It isn't the length of the cable housing that is the issue, but rather
its total curvature. Cable friction is proportional to exp(mu*theta),
where mu is the friction coefficient between cable and shield, and
theta is the total curvature (in radians) of the cable. Depending on
how you routed the bar end cables, they could add upto pi radians
(half turn) compared to brake-lever shifters. Assume (wild ass guess)
mu is 0.2. That corresponds to an increased friction of exp(0.2*pi) =
1.8, or almost twice the friction as a brake-lever shifter.

How did you route the shifter cable? My recollection is that bar end
shifters were traditionally not routed completely along the bar, but
rather just along the bottom of the drops. They then stuck forward and
make a 180 bend. That would give a total curvature about equivalent
to what an Ergo shifter sees. STI has pi/2 less curvature.


Joe

[Joe Riel]

Joe Riel > writes:

> It isn't the length of the cable housing that is the issue, but rather
> its total curvature.

I meant total angle. Curvature generally has units of 1/length.
Total angle is measured in radians.

Joe [slipping]

[James Scott]

Bruce W.1 wrote:
> I'm doing some upgrades to my road touring bike. I ran across the Avid
> Rollamajig. This device looks like very a good idea. But I'm left
> wondering if it would thread into a recent Campagnolo rear derailleur
> like, say, the Veloce.
>
> Anybody have experience with this? Does it work well?

I use one with Mirage 9sp ergo levers and rear derailleur on a frame
with top-routed cables. It's a "shimagnolo" setup with Deore freehub and
SRAM cassette. The rear downshifting is very crisp and requires very
light pressure on the lever - I'm happy with the setup.

JLS
--
James "Standards, shmandards" Scott
www.jls.cx

[Mark Hickey]

Joe Riel > wrote:

>How did you route the shifter cable? My recollection is that bar end
>shifters were traditionally not routed completely along the bar, but
>rather just along the bottom of the drops. They then stuck forward and
>make a 180 bend. That would give a total curvature about equivalent
>to what an Ergo shifter sees. STI has pi/2 less curvature.

Remember that these particular bar end shifters are mounted out on the
end of my aerobars on my time trial bike. There's about 3' (1m) of
cable housing running from the shifters to the down tube cable stops.
Not too many curves in that length - though as you said (in the part I
snipped out) the curved sections certainly do produce the most
friction. No doubt that's why the Rollamajig made a difference
(replacing the one real curve in the whole system).

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

[Joe Riel]

Mark Hickey > writes:

> Joe Riel > wrote:
>
>>How did you route the shifter cable? My recollection is that bar end
>>shifters were traditionally not routed completely along the bar, but
>>rather just along the bottom of the drops. They then stuck forward and
>>make a 180 bend. That would give a total curvature about equivalent
>>to what an Ergo shifter sees. STI has pi/2 less curvature.
>
> Remember that these particular bar end shifters are mounted out on the
> end of my aerobars on my time trial bike.

I had forgotten that, but afterwards figured that that was what you
had done. I was, incorrectly, imagining a standard road bike with bar
end shifters. Not exactly the state-of-the-art time trial machine.

> There's about 3' (1m) of
> cable housing running from the shifters to the down tube cable stops.
> Not too many curves in that length - though as you said (in the part I
> snipped out) the curved sections certainly do produce the most
> friction. No doubt that's why the Rollamajig made a difference
> (replacing the one real curve in the whole system).

I'd have to see the setup, however, it seems as though a time trial
bike with shifters on the aero-bars might have a lower total angle for
shift cables then a standard road bike setup with bar end shifters.
My point, however, was that the friction depends on the angle, not the
length. That is three feet of cable bending through 90 degrees will
exhibit the same friction as six inches of cable bending through 90
degrees.

Joe

[Jeff S.]

A while back weren't several posters recommending the use of v-brake noodles
to do something similar in terms of shifting crispness by reducing tight
housing radiuses at the r/d?

"Mark Hickey" > wrote in message
...
> David Damerell > wrote:
>
> >begin quoting Mark Hickey >:
> >>'Smatter of fact, I happen to have a Rollamajig on a Veloce rear
> >>derailleur on my own time trial bike. Works like a champ. I
> >>installed it to reduce the cable friction (which is considerable since
> >>the shifters are bar end shifters on the end of the aerobars, and are
> >>a LONG way from the derailleurs).
> >
> >Is that really necessary? I don't see 'em on tandems...
>
> My time trial bike has a lot more cable housing than my tandem (which
> really only has as much as a single bike, plus a coupe short pieces to
> carry the cable around the eccentric bottom bracket).
>
> It really did improve the shifting - keep in mind that not only is the
> friction higher with all that extra cable, but the thumbie shifter
> doesn't give nearly the leverage that a longer shifter would.
>
> I eventually converted the shifters to Dura Ace which allow me to use
> them in friction mode - that way I can shift any one of the several
> mismatched rear wheels I want to throw on the bike.
>
> Mark Hickey
> Habanero Cycles
> http://www.habcycles.com
> Home of the $695 ti frame

[Mark Hickey]

Joe Riel > wrote:

>Mark Hickey > writes:

>> Remember that these particular bar end shifters are mounted out on the
>> end of my aerobars on my time trial bike.
>
>I had forgotten that, but afterwards figured that that was what you
>had done. I was, incorrectly, imagining a standard road bike with bar
>end shifters. Not exactly the state-of-the-art time trial machine.

I'm not sure "state-of-the-art" applies, but it ain't no retro-tourer!

>> There's about 3' (1m) of
>> cable housing running from the shifters to the down tube cable stops.
>> Not too many curves in that length - though as you said (in the part I
>> snipped out) the curved sections certainly do produce the most
>> friction. No doubt that's why the Rollamajig made a difference
>> (replacing the one real curve in the whole system).
>
>I'd have to see the setup, however, it seems as though a time trial
>bike with shifters on the aero-bars might have a lower total angle for
>shift cables then a standard road bike setup with bar end shifters.

http://www.habcycles.com/tt-tri.html

The bike in the photo at the top of the page is my own personal bike,
prior to installation of the Rollamajig.

>My point, however, was that the friction depends on the angle, not the
>length. That is three feet of cable bending through 90 degrees will
>exhibit the same friction as six inches of cable bending through 90
>degrees.

I suspect you're right. At any rate, lower friction is good, no
matter how low it was to start with.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

[Mark Hickey]

"Jeff S." > wrote:

>A while back weren't several posters recommending the use of v-brake noodles
>to do something similar in terms of shifting crispness by reducing tight
>housing radiuses at the r/d?

The change from a piece of shift cable (that doesn't really like to be
bent sharply) to a slick piece of solid metal tubing (with very low
internal friction). That's been highly recommended, and I'm sure it
works well.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

>"Mark Hickey" > wrote in message
...
>> David Damerell > wrote:
>>
>> >begin quoting Mark Hickey >:
>> >>'Smatter of fact, I happen to have a Rollamajig on a Veloce rear
>> >>derailleur on my own time trial bike. Works like a champ. I
>> >>installed it to reduce the cable friction (which is considerable since
>> >>the shifters are bar end shifters on the end of the aerobars, and are
>> >>a LONG way from the derailleurs).
>> >
>> >Is that really necessary? I don't see 'em on tandems...
>>
>> My time trial bike has a lot more cable housing than my tandem (which
>> really only has as much as a single bike, plus a coupe short pieces to
>> carry the cable around the eccentric bottom bracket).
>>
>> It really did improve the shifting - keep in mind that not only is the
>> friction higher with all that extra cable, but the thumbie shifter
>> doesn't give nearly the leverage that a longer shifter would.
>>
>> I eventually converted the shifters to Dura Ace which allow me to use
>> them in friction mode - that way I can shift any one of the several
>> mismatched rear wheels I want to throw on the bike.
>>
>> Mark Hickey
>> Habanero Cycles
>> http://www.habcycles.com
>> Home of the $695 ti frame
>

[Joe Riel]

Mark Hickey > writes:

> The bike in the photo at the top of the page is my own personal bike,
> prior to installation of the Rollamajig.

Thanks for the photo. A question about the Rollamajig. What kind
of bearing does the pulley have? Plain, ball, or roller? Does
it have seals?


Joe

[Marty Wallace]

Mark Hickey wrote:
> Joe Riel > wrote:
>
>
>>Mark Hickey > writes:
>
>
>>>Remember that these particular bar end shifters are mounted out on the
>>>end of my aerobars on my time trial bike.
>>
>>I had forgotten that, but afterwards figured that that was what you
>>had done. I was, incorrectly, imagining a standard road bike with bar
>>end shifters. Not exactly the state-of-the-art time trial machine.
>
>
> I'm not sure "state-of-the-art" applies, but it ain't no retro-tourer!
>
>
>>>There's about 3' (1m) of
>>>cable housing running from the shifters to the down tube cable stops.
>>>Not too many curves in that length - though as you said (in the part I
>>>snipped out) the curved sections certainly do produce the most
>>>friction. No doubt that's why the Rollamajig made a difference
>>>(replacing the one real curve in the whole system).
>>
>>I'd have to see the setup, however, it seems as though a time trial
>>bike with shifters on the aero-bars might have a lower total angle for
>>shift cables then a standard road bike setup with bar end shifters.
>
>
> http://www.habcycles.com/tt-tri.html
>
> The bike in the photo at the top of the page is my own personal bike,
> prior to installation of the Rollamajig.
>
>
>>My point, however, was that the friction depends on the angle, not the
>>length. That is three feet of cable bending through 90 degrees will
>>exhibit the same friction as six inches of cable bending through 90
>>degrees.
>
>
> I suspect you're right. At any rate, lower friction is good, no
> matter how low it was to start with.
>
> Mark Hickey
> Habanero Cycles
> http://www.habcycles.com
> Home of the $695 ti frame

Nice Mark

Do you find that you miss being able to hold onto the tops of the bars
with those dropped bullhorns?

Marty

[Mark Hickey]

Joe Riel > wrote:

>Mark Hickey > writes:
>
>> The bike in the photo at the top of the page is my own personal bike,
>> prior to installation of the Rollamajig.
>
>Thanks for the photo. A question about the Rollamajig. What kind
>of bearing does the pulley have? Plain, ball, or roller? Does
>it have seals?

I believe it's a bushing, and that it doesn't have seals. I would
imagine that low-friction bearing (and probably seals) would be
overkill in that application.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

[Mark Hickey]

Marty Wallace > wrote:

>Mark Hickey wrote:

>> http://www.habcycles.com/tt-tri.html
>>
>> The bike in the photo at the top of the page is my own personal bike,
>> prior to installation of the Rollamajig.

>Nice Mark

Thanks.

>Do you find that you miss being able to hold onto the tops of the bars
>with those dropped bullhorns?

Not really - if I were to do a lot of rides/races with long climbs I
might, but I can't say I've ever really missed that position
(especially since it's really still there, but just a little lower,
and at a bit of an angle).

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

[Qui si parla Campagnolo]

It should be pointed out that this gadget is not really required for a der
housing that is of high quality and long enough.

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

[Joe Riel]

Mark Hickey > writes:

> Joe Riel > wrote:
>>
>> [...] A question about the Rollamajig. What kind
>>of bearing does the pulley have? Plain, ball, or roller? Does
>>it have seals?
>
> I believe it's a bushing, and that it doesn't have seals. I would
> imagine that low-friction bearing (and probably seals) would be
> overkill in that application.

A few thoughts on the Rollamajig. From pictures, it appears to turn
the cable through about 120 degrees (2*pi/3 radians). Years ago I
measured the coefficient of friction of new, lined, brake cable to be
0.08 (actually, that's surprisingly low). As mentioned previously,
the force transfer multiplier through Bowden cable is

Kcable = exp(mu*theta).

The force multiplier through a pulley is approximately*

Kpully = 1 + mu*theta*Rb/Rw

where

mu = coefficient of friction
theta = total angle through cable or pulley
Rb = radius of pulley bearing
Rw = radius of pulley wheel

The coefficent of friction for the (presumed) plain bearing of the
Rollamajig (lubricated steel on brass?) will be different from that of
cable on nylon, however, for now let's assume that they are roughly
the same and, with exposure to the elements (i.e. wear and get dirty),
increase by 5X.

From a picture, the ratio Rb/Rw of the Rollamajig appears to be about
1/4. So, plugging in the numbers we get

Kf
New Used
Rollamajig 1.04 1.21
cable 1.18 2.31

So, while a new Rollamajig may not be much of an improvement over a
new cable, when both have been subjected to the elements the
Rollamajig may operate substantially better. Of course, the increase
in friction coefficient was pure speculation.


Joe

* A simplification from a simple model.

[Bill Sornson]

Joe Riel wrote:
> Mark Hickey > writes:
>
>> Joe Riel > wrote:
>>>
>>> [...] A question about the Rollamajig. What kind
>>> of bearing does the pulley have? Plain, ball, or roller? Does
>>> it have seals?
>>
>> I believe it's a bushing, and that it doesn't have seals. I would
>> imagine that low-friction bearing (and probably seals) would be
>> overkill in that application.
>
> A few thoughts on the Rollamajig. From pictures, it appears to turn
> the cable through about 120 degrees (2*pi/3 radians). Years ago I
> measured the coefficient of friction of new, lined, brake cable to be
> 0.08 (actually, that's surprisingly low). As mentioned previously,
> the force transfer multiplier through Bowden cable is
>
> Kcable = exp(mu*theta).
>
> The force multiplier through a pulley is approximately*
>
> Kpully = 1 + mu*theta*Rb/Rw
>
> where
>
> mu = coefficient of friction
> theta = total angle through cable or pulley
> Rb = radius of pulley bearing
> Rw = radius of pulley wheel
>
> The coefficent of friction for the (presumed) plain bearing of the
> Rollamajig (lubricated steel on brass?) will be different from that of
> cable on nylon, however, for now let's assume that they are roughly
> the same and, with exposure to the elements (i.e. wear and get dirty),
> increase by 5X.
>
> From a picture, the ratio Rb/Rw of the Rollamajig appears to be about
> 1/4. So, plugging in the numbers we get
>
> Kf
> New Used
> Rollamajig 1.04 1.21
> cable 1.18 2.31
>
> So, while a new Rollamajig may not be much of an improvement over a
> new cable, when both have been subjected to the elements the
> Rollamajig may operate substantially better. Of course, the increase
> in friction coefficient was pure speculation.
>
>
> Joe
>
> * A simplification from a simple model.

You want simple? My Titus Switchblade ate rear derailleur cables like
string cheese -- always breaking right at the fixing bolt and NOT at the
most opportune times. Then I installed a Roll-a-ma-jig and the cable (which
had a bit of fraying beyond the bolt) lasted about TWO YEARS before finally
fraying a bit /inside/ the bolt and causing some poor shifting. I had
bought a teflon cable long ago just for that bike, and it took all that time
before I got to stick it on.

Bill "I'm a believer" S.

[Joe Riel]

"Bill Sornson" > writes:

> You want simple? My Titus Switchblade ate rear derailleur cables like
> string cheese

Despite the mixed-metaphor, at least it is appropriately named.

Joe