Author Topic: Drivetrain Advice  (Read 5856 times)

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Offline jim

Drivetrain Advice
« on: March 14, 2004, 08:36:12 am »
I am in the process of building a touring bike and am looking for advice on the drivetrain. I want to use a 12-34 cassette with a XT derailleur, a mountain crankset, 22-32-44 or 26-36-48, and STI shifters. I am told a Dura-Ace or Ultegra front derailleur will not work on these chainrings and a XT front derailleur will not work with a STI shifter.  I have been told Shimano makes a Nexave front derailleur that will work but only on a 8 speed cassette. I would like to stay with a 9 speed. I thought about a bar end shifter for the front derailleur but would like to stay with the STI. Any advice or opinions would be appricated.
Thanks,
Jim


Offline DaveB

Drivetrain Advice
« Reply #1 on: March 14, 2004, 10:37:20 pm »
Not sure about Dura Ace but I'm pretty sure an Ultegra front derailleur will work fine with a 26-36-48 crankset.  My son had a Trek that came with an RSX crank with 26-36-46T chainrings and a 105 (same geometry as Ultegra) front derailleur.  It shifted fine with STI despite the small "big" ring.  

Also, I've modified a bunch of 8-speed and 9-speed Shimano road triple cranks from 30-42-52T to 26-42-52T and they also shift well with 105 or Ultegra front derailleurs even though the range exceeds Shimano's published recommendations.

The point of all of this is that the road front derailleurs are pretty tolerant of chainring sizes and total teeth. You should be fine.    


Offline biker_james

Drivetrain Advice
« Reply #2 on: March 15, 2004, 06:43:34 am »
I changed the gearing on my Cannondale to get something better and went with 24/39/48. Shifts fine with a Tiagra derailleur and shifters. I have heard if you go to a 44 that the derailleur cage is the wrong curvature to work well. I would think the Nexave front derailleur would work whether it was meant for 8 or 9 speeds, but you may want to get a more experienced opinion on that one.


Offline iSolo

Drivetrain Advice
« Reply #3 on: March 21, 2004, 11:24:57 pm »
If you're going to spend that much money you might look into
a Rohloff 500/14 Speed hub. Gives the same gears as a
mountain bike but cost from $900 to $1200. I bought one two
years ago and won't go back to using derailluers. No
derailluer problems because I have none. I also put on a
Schlumph speed drive and have a gear inch from 14inches
to 124inches. If you're a weight weenie and worried about it,
the Rohloff will add an extra 1 and 1/2 pounds to the bike.
But you won't have to worry about breakdowns with this
thing. The Rohloff will also save you on chain wear. Besides
the worry free maintanence, being able to shift gears, and
multiple gears at a time, anytime, at a full stop at busy
intersection, or going up a steep hill or peddeling backwards,
is a new experience.

You really got try one before you start knocking it.
18,000 miles on the Rohloff, including the whole CDT and
from Montana to Florida, and 4200 on the Schlumph so far
without a breakdown, of any kind, and I have better gearing
than a mountian bike and road racing bike combined. Now if
I can just find tires that won't go flat.

Keith



Offline DaveB

Drivetrain Advice
« Reply #4 on: March 26, 2004, 10:32:45 am »
Other than cost and weight, the Rohloff hub has two more disadvantages/problems:

1. The shifter is intended for straight bars and not suitable for drop bars.  I've heard of a couple of home made adapters to allow the use of drop bars but they were somewhat jury-rigged and required a fair bit of do-it-yourself construction.

2. The Rohloff hub requires horizontal dropouts to properly tension the chain, rather like a fixed gear or single speed setup.  If you get very lucky with your chainring/cog/chainstay length combination vertical dropouts can work but you can't be sure until you try it.  Rohloff does offer a chain tension device (sort of a stripped down rear derailleur) to allow vertical dropout use but that defeats some of the simplicity of the installation.

BTW, I just looked up the "Schlumpf speed drive" on Sheldon Brown's web site. My first thought was that it was one of his annual April 1 articles but apparently it's real.  What is also is is EXPENSIVE!  One of these plus the Rholoff hub totals over $1300.

The cost of a couple of chainrings and a derailleur or even a new crank is negligable in comparison.  

This message was edited by DaveB on 3-26-04 @ 2:46 PM

Offline iSolo

Drivetrain Advice
« Reply #5 on: March 27, 2004, 04:56:05 am »
Best money I ever spent.  In the past 5 years, before
purchasing both the Shlumpf and Rohloff, I have spent over
$3,700 in just keeping up my two bikes.  The past two years
with only the Rohloff, and the only bike I ride now, I spent
about $50 on chains and oil changes, in two years.  I ride the
bike everyday to work and back. I tour on it and take it out in
the mountains.  

As far as the road bike handle bars go. I've heard that twist
shifter doesn't work on road bars, but that didn't stop Sheldon
Brown from putting one on his bike.  Surprisingly, I've never
had a problem with the rear chain tensioner, but it would
have been nice if my bike had horizontal dropouts. My next
bike will be made with dropouts specifically for the Rohloff. I'll
sell my bike but I won't sell this hub. I almost gave up on it till
after it finally broke in, about 800 miles. Now I won't ever go
back to derailleur systems.

And no. I don't work for Rohloff or even own a bike store. I'm
just really pleased with this hub, and haven't had to do
anything but change the oil once a year. Try putting 18,000
miles, (actually I have close to 19,000 miles on it) on any
derailleur, cassette and hub combo system, without problems
or constant adjustments, and you'll aslo go through three
times as many chains.

But hey, it's not for eveyone. Best investment I ever made for
my bike.

Keith



Offline DaveB

Drivetrain Advice
« Reply #6 on: March 27, 2004, 09:48:29 am »
Your experience with the Rholoff hub has been good and I've heard complimentary things about them from other riders so they do work.    

However, I think your economics are a bit off as 18,000+ miles on a conventional drive train isn't particularly difficult.  I put over 28,000 miles on an 8-speed  105 STI triple drivetrain and my maintainance consisted of five cassettes ($25 each) and five chains ($15 each) in that time.  Both the derailleurs and crank needed no maintainance other than periodic lubing and superficial cleaning.   My experience is typical, not unusual.  

What I don't understand is how you spent $3700 in maintainance costs in five years.  What on earth did you do to those bikes to need that level of expense?


Offline iSolo

Drivetrain Advice
« Reply #7 on: March 27, 2004, 02:36:55 pm »
Actually I spent a lot more than that. $3,700 was just the cost
for replacing rear hub, cassettes, and derailleurs for downhill
races. Now I switch out the Rohloff (the whole wheel) from
my downhill bike to my hardtail for commuting and touring.

Keith

This message was edited by iSolo on 3-27-04 @ 1:39 PM

Offline kiarmuid

Drivetrain Advice
« Reply #8 on: March 27, 2004, 09:59:35 pm »
My wife's bike has 105 STI shifters and a rear XT derailleur and a 12-34 cassette.  I have a XT crank with a 105 front derailleur and dura ace bar end shifter.




Offline DaveB

Drivetrain Advice
« Reply #9 on: March 27, 2004, 10:00:49 pm »
$3,700 was just the cost for replacing rear hub, cassettes, and derailleurs for downhill races.

Aha!!  Now I understand.  In fact I'm surprised it was only $3700!


Offline iSolo

Drivetrain Advice
« Reply #10 on: March 27, 2004, 10:52:54 pm »
What? Now my economics is to low? :) (Just teasing.)

I didn't include the cost for new rims and wheel building. I got
very good at wheel building. I haven't had to rebuild the
wheel since I strung up the Rohloff. (knock wood). My Rohloff
has already paid for itself, several times over. And some
people have over 100,000 miles on this hub, and no one
knows how far it will go before it break downs. Rohloff
doesn't even know yet. Another great advantage of the
Rohloff is being able to shift, anytime. No more anticipating
how many revolutions I'll have to make to get my derailluer to
upshift or downshift before, during, or after a technical. The
Rohloff goes into whatever gear I want instantly. Which is
real nice when commuting and waiting to cross an
intersection at a full stop, or finding yourself in too high of
gear while going up hill and hoping you can force the crank
that extra revolution to downshift, without snaping the chain
or derailluer.

Ok. I'm starting to sound like a cheerleader so I'll stop now.

Keith



Offline jim

Drivetrain Advice
« Reply #11 on: March 28, 2004, 07:40:01 am »
Hey Kiarmuid,

What front derailleur and crankset chainring sizes are on your wife's bike?
Thanks,
Jim