Bike Forums

Bike Forums (https://www.bikeforums.net/forum.php)
-   Bicycle Mechanics (https://www.bikeforums.net/bicycle-mechanics/)
-   -   Not sure if this component combo is going to be a problem (https://www.bikeforums.net/bicycle-mechanics/237950-not-sure-if-component-combo-going-problem.html)

guruguhan 10-17-06 06:30 PM

Not sure if this component combo is going to be a problem
 
Hi again,

So I now have my rear cassette (xt 9spd), RD (xt). My frame is a Giant OCR touring. I will be using barend shifters, but I would like to have the option of going to STI/Ergo in the future if I so choose. I do not have my crankset or an FD yet. My ideal situation is to have a mtn crankset, I can get my hands on an older xtr for example, but I think I ditched the mtn crank idea before because of the problems I'd have with STI/Ergo shifters (even though I won't be using these now, I'd like to have the option). Can I use an xtr (just using this one as an example) crankset with an ultegra/105/tiagra FD and not have problems with bar ends or STI/Ergo (even when using barends, I'll be using indexed shifting except when forced to do otherwise due to a mechanical failure).

Phil from VA 10-17-06 07:33 PM

I understand that all 9 speed road and mountain rear derailleurs from Shimano are indexed the same. I don't believe that is true for front derailleurs. Road and mountain don't mix. I'd recommend you get a road crank for your current setup.

guruguhan 10-17-06 07:37 PM

So I can't use a mtn trpl crank with a road trpl FD? Is this because of different spacing?

Phil from VA 10-17-06 07:43 PM

I believe that the road and mountain shifters pull a different amount of cable. A road shifter and a road front derailleur MAY work with a mountain crankset.

guruguhan 10-17-06 07:50 PM

Looking at the Cannondale 2000, it looks like a mtn crank is used with a tiagra FD (someone else pointed this out to me in another thread, I didn't clue in). Assuming it works well on that bike, do you think it would only work with 26-36-48 cogs, or will 22-32-44 also work?

Phil from VA 10-17-06 07:53 PM

Make sure you have a clamp on front derailleur, which you can move up and down the seattube. If its brazed onto the frame, you will be limited on how small you can go.
Otherwise, it should work.

Retro Grouch 10-17-06 07:59 PM


Originally Posted by guruguhan
Looking at the Cannondale 2000, it looks like a mtn crank is used with a tiagra FD (someone else pointed this out to me in another thread, I didn't clue in). Assuming it works well on that bike, do you think it would only work with 26-36-48 cogs, or will 22-32-44 also work?

The issue is the curve of the derailleur cage. Road front derailleurs are curved to fit a 52 or 53 big ring. It starts to look goofy with anything smaller than a 48 tooth ring and shifting quality is going to deteriorate as you use smaller and smaller rings.

Al1943 10-17-06 08:04 PM


Originally Posted by Phil from VA
Make sure you have a clamp on front derailleur, which you can move up and down the seattube. If its brazed onto the frame, you will be limited on how small you can go.
Otherwise, it should work.

+1
Biggest issue I know of is with braze-on type derailleurs, they won't go low enough. The ones I've seen will only go low enough for a 50t big ring, depends on the frame.

Al

Phil from VA 10-17-06 08:08 PM

That gearing might limit you to a 10 mph top speed. Plan on climbing some Alps?

Grand Bois 10-18-06 07:11 AM

Here's a 105 FD and a 46t big ring. You can see the mismatch in the curve of the cage. It shifts just fine. Rivendell sometimes uses this setup on the Atlantis. That's how I knew I could get away with it. The real problem on this particular frame is the clearance between the end of the cage and the rear shifter cable. I have it set as close as possible without touching.
http://thumb9.webshots.net/t/36/36/9...1YdAZEe_th.jpg

HillRider 10-18-06 07:21 AM


Originally Posted by Phil from VA
That gearing might limit you to a 10 mph top speed. Plan on climbing some Alps?

Dunno 'bout that. Using 700c wheels, a 44T "big ring" with an 11T cog gives a 108 gear-inch high gear or the same as a 52x13. A cadence of 100 rpm produces over 32 mph. Isn't that enough?

guruguhan 10-18-06 11:12 AM

Thanks hillrider and dirtdrop, I used Sheldon's calculator and it was his articles on touring that made me look into choosing my gearing to best suit how I ride. And I've done a fair share of reading and was riding a Cannondale T800. I know I want lower gears.

Why no custom made FDs? If its a clamp on design, wouldn't it be fairly easy (relative to other custom jobs I've seen on these forums) to use a shimano FD, but create a new cage? I wont be doing this, but I'm curious.

guruguhan 10-18-06 11:17 AM


Originally Posted by Al1943
+1
Biggest issue I know of is with braze-on type derailleurs, they won't go low enough. The ones I've seen will only go low enough for a 50t big ring, depends on the frame.

Al

And this is due to the height of the braze-on? What if a braze-on was used with an adapter clamp? (Asking in the event I am given a braze-on FD)

guruguhan 10-18-06 11:22 AM


Originally Posted by Phil from VA
That gearing might limit you to a 10 mph top speed. Plan on climbing some Alps?

Nope.

Mentor58 10-18-06 12:45 PM

Having been there and done that, let me assure you that you can use a MTB crank with a road Shifter, as long as you use a ROAD FD. Yes, it looks more than a bit odd, but it can and does work very nicely for me on 2 different bikes. You want to have a bit a patience getting it set up, you may not be able to get the FD mounted as close to the big chainring as you want, but it will work.

My experence is that by following the basic Park Tools Web Site directions that I needed about 15 minutes to get the shifting 'OK', and about another 30 minutes of fine tuning on limit screws and tension to get it dialed in while riding.

You MAY want to look at getting a chain watcher, it makes it a lot less likely to drop a chain going to the granny ring.

Go for it, it can be done, has been done, and gets ridden on a regular basis.

Steve W.


All times are GMT -6. The time now is 02:03 PM.


Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.