Front Derailleur road-mtb compatibility issues
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  1. #1
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    Front Derailleur road-mtb compatibility issues

    Hello, first time poster here! My quarantine project was putting drop bars on my 1989 Gary Fisher mountain bike (since it's trendy, I like to tinker, and I can't fit bigger than 35s on my CX bike). I've learned tons of invaluable lessons and tricks through the process.

    The main problem is the old mountain FD (Shimano Deore LX) had a different pull than what's compatible with my Shimano Claris road brifter (which I want to use), so I'm on the hunt for a compatible triple FD or other solution. Bike stats:

    • 1989 Gary Fisher CR-7
    • Shimano Claris 3x8 brifters
    • Triple chainring (26-34-48)
    • 8 speed cassette (11-30) w/ Claris R2000 long cage RD
    • 8 speed chain (SRAM PC-870)
    • 34.9mm seat tube

    It seems I need a road FD with:
    • 22T capacity
    • 48T big chainring compatible
    • fits 34.9mm seat tube (or get a braze-on w/ adapter)
    • preferably a 66-69 degree chainstay angle (seems unlikely)
    • fits an 8 speed cassette

    I tried using a microSHIFT R8 triple FD (20T capacity, 50-39-30 top gear teeth), but I think my small chainring (26) and/or capacity (need 22T) are causing it to work pretty poorly.

    What should I worry about most? Getting a 22T capacity FD? Would a FD meant for 9 or 10 speeds work if I get a 9 or 10 speed chain? Do any road FD's work well with 48T to 26T triple cranks?

    Thanks!

  2. #2
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    Why are you changing the FD? It must be the pull ratio?
    I did 2 mtn bikes in the last 2 years with road bars. I used the original FD/RD with a Tiagra triple shifters. It worked ok, but I had mech disks. I still have them if your interested as I no longer use them.
    Then I wanted hydraulic brakes (necessary cause of a mtn) and updated to hydaulic 11 spd shifter/brakes and put on SunRace indexed downtube shifters mounted on the TTube near the HTube to run the gears. If you shift a lot, it's not so good, but going up a mtn you don't shift that much and coming down you really really need the hydraulic brakes.
    BANNED

  3. #3
    'brifter' is f'ing stupid
    Reputation: cxwrench's Avatar
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    Shifters...jesus...they're shifters.
    #promechaniclife

  4. #4
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    Quote Originally Posted by duriel View Post
    Why are you changing the FD? It must be the pull ratio?
    I did 2 mtn bikes in the last 2 years with road bars. I used the original FD/RD with a Tiagra triple shifters. It worked ok, but I had mech disks. I still have them if your interested as I no longer use them.
    Then I wanted hydraulic brakes (necessary cause of a mtn) and updated to hydaulic 11 spd shifter/brakes and put on SunRace indexed downtube shifters mounted on the TTube near the HTube to run the gears. If you shift a lot, it's not so good, but going up a mtn you don't shift that much and coming down you really really need the hydraulic brakes.
    Yes, the original front derailleur had a different pull ratio. My shifters are also indexed, so whatever I get to replace it won't be perfect (like it sounds like you've experience), but I can trim a little bit with the Claris, which helps. I'm trying to figure out what would be most important to look for in a FD. That's probably subjective for each rider anyways - just seeing what other people think. And I'll be using the FD to shift in a variety of conditions, not just for uphill/downhill mtb runs.

  5. #5
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    Quote Originally Posted by cxwrench View Post
    Shifters...jesus...they're shifters.
    *STI dual-control brake-shifter

  6. #6
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    Quote Originally Posted by jayblake View Post
    *STI dual-control brake-shifter
    You have to understand CXWrench. He has a few pet peeves one of which is the word "brifter". Shifter is in fact the correct word even though the device both shifts and brakes.

    The other thing CX get bent out of shape about is when people post in the wrong section. He's very knowledgeable and helpful, but gets curmudgeony sometimes. Give him a back rub and he can actually be a soft, cuddly bunny. Just don't walk on his lawn!
    "COMPLACENCY IS LETHAL - VOTE in November." - System Shock.

    "With
    bicycles in particular, you need to separate between what's merely true and what's important."
    -- DCGriz, RBR.





  7. #7
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    Quote Originally Posted by jayblake View Post
    Yes, the original front derailleur had a different pull ratio.
    That's why you run a Tiagra, it has the same pull ratio so you can use the FD that comes with the bike. You never answered why you changed it, other than it don't work with your shifters. Your shifters are the problem, not the FD.
    BANNED

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