SRAM internal gear hub shifter on drop bars

[dvt]

I see a few historic threads here regarding SRAM shifters and drop bars,
but I don't see the answer to this one. Several ideas for mounting grip
shifters on drop bars have been proposed, and I summarize them here for
future Googlers to find:

1. use an MTB bar-end extension (Sheldon Brown or Alex Wetmore?,
http://www.sheldonbrown.com/harris/atlantis/atlantis640-01.jpg)
2. make your own grip shifter (Tom Ace,
http://www.qnet.com/~crux/twist.html)
3. use a Minoura Spacegrip (Alex Wetmore?, http://tinyurl.com/5ow8y)
4. modify the grip shifter (Sheldon Brown,
http://sheldonbrown.com/scott.html#gripshift)

I don't see anyone suggesting technique #4 for using the internal gear
shifters on a drop bar. Is there a reason this wouldn't work?

I've never played around with a grip shifter of any sort, so I don't
know if there is a difference between the derailer type and internal
gear type that would preclude this sort of mounting. Thanks for any help.

--
Dave
dvt at psu dot edu

 

[Werehatrack]

On Wed, 17 Nov 2004 14:29:41 -0500, dvt <[email protected]> wrote:

>4. modify the grip shifter (Sheldon Brown,
>http://sheldonbrown.com/scott.html#gripshift)
>
>I don't see anyone suggesting technique #4 for using the internal gear
>shifters on a drop bar. Is there a reason this wouldn't work?

Gearhub shifters are special. While SRAM makes a gripshift for the
3-speed SRAM gearhubs, I'm pretty sure that you'd have a challenge
fitting it to a drop bar. IIRC, they have a metal collar that will
probably not slip past the curves. Of course, if you just want to
mount it in the drop, it might work if the bar's tube is the right
diameter.

Gearhubs are generally not the device of choice for a touring or road
bike...for a number of reasons.
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[dvt]

Thanks for the tip on the metal collar. That's just the kind of thing I
was wondering about.

Werehatrack wrote:
> Gearhubs are generally not the device of choice for a touring or road
> bike...for a number of reasons.

I'd like to hear about that. I know they're less efficient and parts are
less widely available, which are sore spots for racing or touring, but
those are not serious problems for me. I'd like to hear a few more of
your reasons.

I plan to use it for commuting about 15 miles per day. I have been
riding through the winter for several years now, and I really like the
idea of a bike that still shifts nicely in February without a lot of
maintenance. I love the low maintenance of my fixie, but my knees
complain when I ride that bike several times per week.

--
Dave
dvt at psu dot edu

 

[meb]

Thanks for the tip on the metal collar. That's just the kind of thing I
was wondering about.

Werehatrack wrote:
> Gearhubs are generally not the device of choice for a touring or road
> bike...for a number of reasons.

I'd like to hear about that. I know they're less efficient and parts are
less widely available, which are sore spots for racing or touring, but
those are not serious problems for me. I'd like to hear a few more of
your reasons.

I plan to use it for commuting about 15 miles per day. I have been
riding through the winter for several years now, and I really like the
idea of a bike that still shifts nicely in February without a lot of
maintenance. I love the low maintenance of my fixie, but my knees
complain when I ride that bike several times per week.

--
Dave
dvt at psu dot edu

For commuting, the internal gear hub's ability to shift at a stop and reliability and reduced mainentance trump the efficiency and weight advantages of the deraileur bikes. On a tourer, those iadvantages are present though not as pronounced since you don't stop quite as much and are often in more hospitable environs.
.

 

[Werehatrack]

On Wed, 17 Nov 2004 19:26:05 -0500, dvt <[email protected]>
wrote:

>Thanks for the tip on the metal collar. That's just the kind of thing I
>was wondering about.
>
>Werehatrack wrote:
>> Gearhubs are generally not the device of choice for a touring or road
>> bike...for a number of reasons.
>
>I'd like to hear about that. I know they're less efficient and parts are
>less widely available, which are sore spots for racing or touring, but
>those are not serious problems for me. I'd like to hear a few more of
>your reasons.
>
>I plan to use it for commuting about 15 miles per day. I have been
>riding through the winter for several years now, and I really like the
>idea of a bike that still shifts nicely in February without a lot of
>maintenance. I love the low maintenance of my fixie, but my knees
>complain when I ride that bike several times per week.

For commuting in near-level territory, the principle disadvantages
relative to a der system are moot. For that application, the extended
range of gears and the lower weight of the der system do not provide
enough of an advantage to offset the simplicity, reliability and
convenience of the gear hub in my opinion. In touring, however,
riders usually want a broader range of gears than the 3-speed gearhub
can provide, and on road bikes, the weight penalty and inefficiency
are widely viewed as killer issues. As a result, gearhubs are very
uncommon on touring and road bikes, though they are a mainstay of the
"comfort bike" market in the US, and very common on city bikes in the
rest of the world. 3-speed hubs used to be much more common in the US
than they are now, but the lower cost of the der system has largely
displaced them from the low-end and midrange bikes. I still see a lot
of them on bikes in thrift stores, though.
--
Typoes are a feature, not a bug.
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[dvt]

Werehatrack wrote:
> For commuting in near-level territory, the principle disadvantages
> relative to a der system are moot. For that application, the extended
> range of gears and the lower weight of the der system do not provide
> enough of an advantage to offset the simplicity, reliability and
> convenience of the gear hub in my opinion.

Well, I'm looking at a 5- or 7-speed hub, which have a wider gear range
(250-300%) than the traditional 3-speed hubs (~180%). The 250-300% range
of gears looks like plenty to me. 300% can give me a 30" and a 90" gear;
that's a pretty wide spread for a single bike used on pavement. I do
plan to use it in a hilly environment.

> In touring, however,
> riders usually want a broader range of gears than the 3-speed gearhub
> can provide...

I have no plans to tour with this hub.

> ...on road bikes, the weight penalty and inefficiency
> are widely viewed as killer issues.

I have no intention of racing on this bike. I might decide to use it on
an occasional long ride, but the inefficiency will probably be a benefit
in the winter since I should stay warmer.

> ...the lower cost of the der system has largely
> displaced them [3-spd hubs] from the low-end and midrange bikes.

Isn't that the truth! You can buy an entire department store bike for
less than the cost of a 7-speed hub and shifter. I suppose if the
production quantities of these hubs increased, the price would decrease.
It's a catch-22, since demand won't go up until the price decreases. And
even if the prices did come down, I'll bet the price of an internal-gear
hub would still be higher than the drivetrain on a department store
bike. So I don't see them becoming 'mainstream' any time soon.

--
Dave
dvt at psu dot edu

 

[Tom Ace]

Werehatrack wrote

> convenience of the gear hub in my opinion. In touring, however,
> riders usually want a broader range of gears than the 3-speed gearhub
> can provide, and on road bikes, the weight penalty and inefficiency
> are widely viewed as killer issues.

I'm not sure why you're commenting on 3-speed hubs, given that hubs
with more speeds are available (from SRAM and others).

Hub gearing has a bunch of pros and cons; whether it's worth it depends
on your priorities. In addition to the points already mentioned in this
thread, I like having a no-dish rear wheel and I like the look of a
single chainwheel.

In response to dvt's posting that started this thread--
An SRAM hub relies on indexing in the grip, thus the kind of grip I made
wouldn't work with it. (My web page about a homemade twist grip has
moved to a new home at http://www.minortriad.com/twist.html )

Tom Ace

 

[Werehatrack]

On 18 Nov 2004 09:16:40 -0800, [email protected] (Tom Ace) wrote:

>In response to dvt's posting that started this thread--
>An SRAM hub relies on indexing in the grip, thus the kind of grip I made
>wouldn't work with it. (My web page about a homemade twist grip has
>moved to a new home at http://www.minortriad.com/twist.html )

SRAM makes a twist-grip specifically for their 3-speed gearhubs, but
not for the ones with 5 or 7. That's why I was only addressing the
issue of the 3-speed hub; the topic was the adaptation of such a
twist-grip to drop bars (unlikely to work unless mounted in the drop
or on an mtb bar end).

For my part, I really don't like twist-grips. I'd much rather have a
lever, preferably in a convenient location. And I rather like
gearhubs for ordinary riding, though at present anything more than a
3-speed is still beyond the budget unless I happen to find an
accidental windfall somewhere.

Anyway, aside from the advantage of clean looks, gearhubs also reduce
the bike's exposure to damage due to collision with debris and other
such mishaps; they don't have the relatively fragile rear der and
dropout lug which is exposed on a der system. (And yes, I've seen the
guards that can be installed; not all that effective in my
experience.)
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
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[dvt]

Werehatrack wrote:
> SRAM makes a twist-grip specifically for their 3-speed gearhubs, but
> not for the ones with 5 or 7. ...the topic was the adaptation of such a
> twist-grip to drop bars (unlikely to work unless mounted in the drop
> or on an mtb bar end).

Maybe we're talking about different things. I think the *only* shifter
available for the 5 or 7 speed hubs is a twist-grip shifter. See, for
example, http://www.sram.com/en/sram/comfort/p5/shiftclick.php for the
shifter that goes with the 5 speed hub. I'm calling that a grip shifter;
maybe I'm using the wrong term and confusing you.

> For my part, I really don't like twist-grips. I'd much rather have a
> lever, preferably in a convenient location.

I can't argue with that, especially since a lever would be easier to put
on a drop bar. But as I said above, I think the 5 and 7 speed hubs are
available only with a grip shift.

> ...gearhubs also reduce
> the bike's exposure to damage due to collision with debris and other
> such mishaps; they don't have the relatively fragile rear der and
> dropout lug which is exposed on a der system.

On the other hand, SRAM gear hubs have their "clickbox" exposed to
mishaps. The clickbox is probably cheaper to replace than a rear
derailler, so I suppose that's an advantage.

The Shimano internal gear hubs have nothing outside the frame except the
axle and nuts. That's a big advantage in the Shimano column, since the
fragile parts are all pretty well protected. The corresponding
disadvantage is that the wheel is reportedly harder to remove in case of
a flat tire.

--
Dave
dvt at psu dot edu

 

[Werehatrack]

On Thu, 18 Nov 2004 16:42:40 -0500, dvt <[email protected]> wrote:

>Werehatrack wrote:
>> SRAM makes a twist-grip specifically for their 3-speed gearhubs, but
>> not for the ones with 5 or 7.

Ooops. I was wrong there.

>> ...the topic was the adaptation of such a
>> twist-grip to drop bars (unlikely to work unless mounted in the drop
>> or on an mtb bar end).
>
>Maybe we're talking about different things. I think the *only* shifter
>available for the 5 or 7 speed hubs is a twist-grip shifter. See, for
>example, http://www.sram.com/en/sram/comfort/p5/shiftclick.php for the
>shifter that goes with the 5 speed hub. I'm calling that a grip shifter;
>maybe I'm using the wrong term and confusing you.
>
>> For my part, I really don't like twist-grips. I'd much rather have a
>> lever, preferably in a convenient location.
>
>I can't argue with that, especially since a lever would be easier to put
>on a drop bar. But as I said above, I think the 5 and 7 speed hubs are
>available only with a grip shift.

Looks like you're right. OTOH, unless I'm mistaken, all of the
Shimano Nexus setups that I see in the local shops are set up with the
trigger shifters; I guess I was thinking of those. (Shimano makes
both types of shifter for the Nexus according to their catalog.)

>The Shimano internal gear hubs have nothing outside the frame except the
>axle and nuts. That's a big advantage in the Shimano column, since the
>fragile parts are all pretty well protected. The corresponding
>disadvantage is that the wheel is reportedly harder to remove in case of
>a flat tire.

The people close to one friend who has a Nexus-7 agree with that
statement. I've heard from her father and her boyfriend that they've
both decided that the next time she has a flat, she'll be getting a
lesson in how to R&R that wheel herself...because *she* was the one
who insisted on that particular Bianchi.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

 

[Gary Young]

[email protected] (Tom Ace) wrote in message news:<[email protected]>...
> Werehatrack wrote
>
> > convenience of the gear hub in my opinion. In touring, however,
> > riders usually want a broader range of gears than the 3-speed gearhub
> > can provide, and on road bikes, the weight penalty and inefficiency
> > are widely viewed as killer issues.
>
> I'm not sure why you're commenting on 3-speed hubs, given that hubs
> with more speeds are available (from SRAM and others).
>
> Hub gearing has a bunch of pros and cons; whether it's worth it depends
> on your priorities. In addition to the points already mentioned in this
> thread, I like having a no-dish rear wheel and I like the look of a
> single chainwheel.
>
> In response to dvt's posting that started this thread--
> An SRAM hub relies on indexing in the grip, thus the kind of grip I made
> wouldn't work with it. (My web page about a homemade twist grip has
> moved to a new home at http://www.minortriad.com/twist.html )
>
> Tom Ace


Just out of curiousity, could an STI or Ergo shifter be made to work
with a 7 or 8-speed internal-gearhub by making an adaptor like the
ShiftMate? (See: http://www.jtekengineering.com/shiftmate.htm)

 

[Jim Smith]

[email protected] (Gary Young) writes:

> Just out of curiousity, could an STI or Ergo shifter be made to work
> with a 7 or 8-speed internal-gearhub by making an adaptor like the
> ShiftMate? (See: http://www.jtekengineering.com/shiftmate.htm)

I've ben thinking along those lines myself lately. If somebody makes
these, I'll buy one.

 

[dvt]

Gary Young wrote:
> Just out of curiousity, could an STI or Ergo shifter be made to work
> with a 7 or 8-speed internal-gearhub by making an adaptor like the
> ShiftMate? (See: http://www.jtekengineering.com/shiftmate.htm)

Now that's kewl! Along those lines, I have heard that a local boy has
figured out how to use a bar-end shifter to shift his internal gear hub
using a travel agent, but I haven't been able to get in touch with him
to ask exactly how he did it.

I have Shimano 6, 7, 8, and 9-speed indexed shifters for derailers at
home. I'll be happy to measure the cable throw of those shifters. If
someone else can measure the cable throw of their shifters for internal
hubs, we could figure out the required ratio. Once we know that ratio,
I'll bet we can find a the proper ShiftMate to make one of those
shifters work. Based on past (and current) discussions in this group, I
think we'd be doing a public service.

--
Dave
dvt at psu dot edu

 

[meb]

Gary Young wrote:
> Just out of curiousity, could an STI or Ergo shifter be made to work
> with a 7 or 8-speed internal-gearhub by making an adaptor like the
> ShiftMate? (See: http://www.jtekengineering.com/shiftmate.htm)

Now that's kewl! Along those lines, I have heard that a local boy has
figured out how to use a bar-end shifter to shift his internal gear hub
using a travel agent, but I haven't been able to get in touch with him
to ask exactly how he did it.

I have Shimano 6, 7, 8, and 9-speed indexed shifters for derailers at
home. I'll be happy to measure the cable throw of those shifters. If
someone else can measure the cable throw of their shifters for internal
hubs, we could figure out the required ratio. Once we know that ratio,
I'll bet we can find a the proper ShiftMate to make one of those
shifters work. Based on past (and current) discussions in this group, I
think we'd be doing a public service.

--
Dave
dvt at psu dot edu

Don't forget to check the throw linearity over the entire shift range.

 

[dvt]

dvt wrote:
> I have Shimano 6, 7, 8, and 9-speed indexed shifters for derailers at
> home. I'll be happy to measure the cable throw of those shifters. If
> someone else can measure the cable throw of their shifters for internal
> hubs, we could figure out the required ratio. Once we know that ratio,
> I'll bet we can find a the proper ShiftMate to make one of those
> shifters work. Based on past (and current) discussions in this group, I
> think we'd be doing a public service.

I have made some measurements and collected some info from Jay Guthrie,
the person behind the ShiftMate
(http://www.jtekengineering.com/shiftmate.htm). I put the data below.
Please let me know if you have insider information or more accurate
numbers than I got with my calipers.

Each of the cable throw numbers is for the total range of gears. Use the
formula TOTAL/(N-1) to get the cable pull per indexed click, where N is
the number of gears in the system.

Shimano 6 and 7-speed: 18.3 mm
Shimano 8-9-10 speed: 21.2 mm
"Old?" Campy: 26.7 mm
"New?" Campy: 25.4 mm
SRAM Spectro P7: 66.1 mm
Shimano Nexus 7: 34.9 mm

I've made the assumption that each click gives the same amount of cable
pull; it looks like a decent assumption when I look at the shifter in
operation, but I don't have measurements. And I don't know what "New"
and "Old" Campy means. Jay gave me those numbers, and I didn't ask what
they meant since I don't have any Campy stuff.

A few things to note:

1. A travel agent intended for brake levers gives about 2:1 change in
cable throw based on my rough measurements.

2. The 7-spd internal gear hubs (IGH) require a lot of cable throw per
click. The Shimano Nexus 7 would requires 1.9 times more cable pull than
a Shimano 7-speed indexed shifter. The SRAM P7 uses almost twice the
pull of the Nexus!

2a. Jay Guthrie pointed out that increasing the cable pull will increase
the force on a shifter, and the derailler-type shifters may not be
strong enough to handle that force.

2b. The big difference in cable pull would mean a very large device if
you use the ShiftMate or travel agent technique.

3. Jay also noted that the typical operation of an IGH shifter is
reverse that of a normal shifter. It would be like using a rapid-rise or
low-normal derailer. I think I could get used to a backwards shifter,
but it would be a bit of a pain to switch back to my derailler bike
after getting used to the switch.

Bottom line: it looks like it would be pretty difficult to use any other
shifter with the SRAM P7 since the cable pull per click is aroud 3-4
times different than most standard indexing shifters. The Nexus 7 looks
more feasible, but there would seem to be a few drawbacks (i.e. the
increased force on the shifter and reversed operation).

--
Dave
dvt at psu dot edu

 

[Gary Young]

dvt <[email protected]> wrote in message news:<[email protected]>...
> dvt wrote:
> > I have Shimano 6, 7, 8, and 9-speed indexed shifters for derailers at
> > home. I'll be happy to measure the cable throw of those shifters. If
> > someone else can measure the cable throw of their shifters for internal
> > hubs, we could figure out the required ratio. Once we know that ratio,
> > I'll bet we can find a the proper ShiftMate to make one of those
> > shifters work. Based on past (and current) discussions in this group, I
> > think we'd be doing a public service.
>
> I have made some measurements and collected some info from Jay Guthrie,
> the person behind the ShiftMate
> (http://www.jtekengineering.com/shiftmate.htm). I put the data below.
> Please let me know if you have insider information or more accurate
> numbers than I got with my calipers.
>
> Each of the cable throw numbers is for the total range of gears. Use the
> formula TOTAL/(N-1) to get the cable pull per indexed click, where N is
> the number of gears in the system.
>
> Shimano 6 and 7-speed: 18.3 mm
> Shimano 8-9-10 speed: 21.2 mm
> "Old?" Campy: 26.7 mm
> "New?" Campy: 25.4 mm
> SRAM Spectro P7: 66.1 mm
> Shimano Nexus 7: 34.9 mm
>
> I've made the assumption that each click gives the same amount of cable
> pull; it looks like a decent assumption when I look at the shifter in
> operation, but I don't have measurements. And I don't know what "New"
> and "Old" Campy means. Jay gave me those numbers, and I didn't ask what
> they meant since I don't have any Campy stuff.
>
> A few things to note:
>
> 1. A travel agent intended for brake levers gives about 2:1 change in
> cable throw based on my rough measurements.
>
> 2. The 7-spd internal gear hubs (IGH) require a lot of cable throw per
> click. The Shimano Nexus 7 would requires 1.9 times more cable pull than
> a Shimano 7-speed indexed shifter. The SRAM P7 uses almost twice the
> pull of the Nexus!
>
> 2a. Jay Guthrie pointed out that increasing the cable pull will increase
> the force on a shifter, and the derailler-type shifters may not be
> strong enough to handle that force.
>
> 2b. The big difference in cable pull would mean a very large device if
> you use the ShiftMate or travel agent technique.
>
Wouldn't the travel agent be almost the exact size needed for Shimano
7-speed STI levers mated with a 7-speed Nexus hub? Unless my
calculations are wrong (a distinct possibility), the STI lever would
pull about 5% too much cable with each shift. Could you compensate by
filing down the cable track in the travel agent? (I don't have any of
this equipment or I'd try it myself.)

> 3. Jay also noted that the typical operation of an IGH shifter is
> reverse that of a normal shifter. It would be like using a rapid-rise or
> low-normal derailer. I think I could get used to a backwards shifter,
> but it would be a bit of a pain to switch back to my derailler bike
> after getting used to the switch.
>
> Bottom line: it looks like it would be pretty difficult to use any other
> shifter with the SRAM P7 since the cable pull per click is aroud 3-4
> times different than most standard indexing shifters. The Nexus 7 looks
> more feasible, but there would seem to be a few drawbacks (i.e. the
> increased force on the shifter and reversed operation).

 

[dvt]

Gary Young wrote:
>>Each of the cable throw numbers is for the total range of gears. Use the
>>formula TOTAL/(N-1) to get the cable pull per indexed click, where N is
>>the number of gears in the system.
>>
>>Shimano 6 and 7-speed: 18.3 mm
>>Shimano 8-9-10 speed: 21.2 mm
>>"Old?" Campy: 26.7 mm
>>"New?" Campy: 25.4 mm
>>SRAM Spectro P7: 66.1 mm
>>Shimano Nexus 7: 34.9 mm
>>
>>I've made the assumption that each click gives the same amount of cable
>>pull; it looks like a decent assumption when I look at the shifter in
>>operation, but I don't have measurements. And I don't know what "New"
>>and "Old" Campy means. Jay gave me those numbers, and I didn't ask what
>>they meant since I don't have any Campy stuff.
>>
>>A few things to note:
>>
>>1. A travel agent intended for brake levers gives about 2:1 change in
>>cable throw based on my rough measurements.
>>
>>2. The 7-spd internal gear hubs (IGH) require a lot of cable throw per
>>click. The Shimano Nexus 7 would requires 1.9 times more cable pull than
>>a Shimano 7-speed indexed shifter. The SRAM P7 uses almost twice the
>>pull of the Nexus!

> Wouldn't the travel agent be almost the exact size needed for Shimano
> 7-speed STI levers mated with a 7-speed Nexus hub? Unless my
> calculations are wrong (a distinct possibility), the STI lever would
> pull about 5% too much cable with each shift. Could you compensate by
> filing down the cable track in the travel agent? (I don't have any of
> this equipment or I'd try it myself.)

That seems about right. I have ordered a SRAM hub, though, so I won't be
able to try it.

Filing down the cable track in the travel agent sounds like it would be
a little tricky. You might need a basic machine tool or two (i.e. a
lathe or a drill press), and most people won't be interested in that. I
wouldn't do it unless I really wanted to use the Shimano hub.

--
Dave
dvt at psu dot edu

 

[Bill Putnam]

dvt <[email protected]> wrote in message news:<[email protected]>...
....
> Well, I'm looking at a 5- or 7-speed hub, which have a wider gear range
> (250-300%) than the traditional 3-speed hubs (~180%). The 250-300% range
> of gears looks like plenty to me. 300% can give me a 30" and a 90" gear;
> that's a pretty wide spread for a single bike used on pavement. I do
> plan to use it in a hilly environment.

....
One option is to find an old Sturmey Archer S5.2 5 speed hub. These
come up on e bay occasionally. I paid around $45 for the last one I
bought. Although the S5.2's range is not as great as some of the
newer hubs, it is greater than a Sturmey 3 speed and the gaps between
gears are smaller than the common Sturmey AW. I use a 42 tooth
chainring and 22 tooth sprocket giving a low of 34 inches and high of
77.

With the S5.2 hub you can use two standard 3 speed triggers. These
can be mounted on a the drops of a drop bar with the triggers pointing
to the rear. Or these can be mounted on the upper portion of a drop
bar and with some careful bending of the trigger lever (use the older
style pre CPSC that don't have the big plastic ball on the end). Many
parts are interchangable with the common AW so indicator rods and
other control parts (cables, pulleys and so on) are readily available.
I consider the control mechanism to be more robust and easily
repaired than the modern designs, also it is no big deal to remove the
wheel to fix a flat.

Although the initial price might be greater than a department store
bike, these hubs are durable. I have about 20,000 miles on my S5.2
hub and the only parts that have been replaced are the indicator rods
and shift cables. I replace the chain on the bike annually but it is
an inexpensive 3 speed width chain rather than the more expensive
narrow chains sold for derailler equipped bikes. Rear sprockets are
quite a bit more durable than hyperglide cogs. I've worn out two rims
from braking but have reused the spokes each time. This is a bike
that is ridden year round in Wisconsin, USA, so salt and sand do take
their toll on rims and chains.

I used to ride a derailler equipped bike for commuting, but tired of
the frequent need to replace more expensive chains, freewheels, and
deraillers. Plus in the winter the freewheels would get packed with
snow and the chain would skip over the cogs. For commuting I find an
internal gear hub to be much less hassle, lower cost overall, and
adequate in gear range and spacing.

Bill Putnam

 

[[email protected]]

The hub plus a derailleur I see being used. With only
one ring up front. 7 speed hub and a 8 speed cassette and derailleur.
Makes a nice chain line I guess.

I MTB 2004

 

[Gary Young]

dvt <[email protected]> wrote in message news:<[email protected]>...
> Gary Young wrote:
> >>Each of the cable throw numbers is for the total range of gears. Use the
> >>formula TOTAL/(N-1) to get the cable pull per indexed click, where N is
> >>the number of gears in the system.
> >>
> >>Shimano 6 and 7-speed: 18.3 mm
> >>Shimano 8-9-10 speed: 21.2 mm
> >>"Old?" Campy: 26.7 mm
> >>"New?" Campy: 25.4 mm
> >>SRAM Spectro P7: 66.1 mm
> >>Shimano Nexus 7: 34.9 mm
> >>
> >>I've made the assumption that each click gives the same amount of cable
> >>pull; it looks like a decent assumption when I look at the shifter in
> >>operation, but I don't have measurements. And I don't know what "New"
> >>and "Old" Campy means. Jay gave me those numbers, and I didn't ask what
> >>they meant since I don't have any Campy stuff.
> >>
> >>A few things to note:
> >>
> >>1. A travel agent intended for brake levers gives about 2:1 change in
> >>cable throw based on my rough measurements.
> >>
> >>2. The 7-spd internal gear hubs (IGH) require a lot of cable throw per
> >>click. The Shimano Nexus 7 would requires 1.9 times more cable pull than
> >>a Shimano 7-speed indexed shifter. The SRAM P7 uses almost twice the
> >>pull of the Nexus!
>
> > Wouldn't the travel agent be almost the exact size needed for Shimano
> > 7-speed STI levers mated with a 7-speed Nexus hub? Unless my
> > calculations are wrong (a distinct possibility), the STI lever would
> > pull about 5% too much cable with each shift. Could you compensate by
> > filing down the cable track in the travel agent? (I don't have any of
> > this equipment or I'd try it myself.)
>
> That seems about right. I have ordered a SRAM hub, though, so I won't be
> able to try it.
>
> Filing down the cable track in the travel agent sounds like it would be
> a little tricky. You might need a basic machine tool or two (i.e. a
> lathe or a drill press), and most people won't be interested in that. I
> wouldn't do it unless I really wanted to use the Shimano hub.


I was thinking you could just use a needle file to create a flat spot.
Is there some reason the track has to be concentric and perfectly
round?