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  1. #1
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    Merged: Shimano is making my head hurt. Front Derailleur chat. Lots of pics....

    Tryng to finish up my BMC Fourstroke and need a few more parts. One snag is the front derailleur. I mean, thanks Shimano, more choices are great, when they are better explained.... Unfortunately, model numbers and a price tag dont help when most of the resellers copy and paste the same blurb.

    A bit of background. I do the carbon cranks, yes, we all should know by now. My new Integrated Carbon Crank is 720g with an outboard Ti BB spindle and I took off a 50T chain ring from one of my compact cranks, because lets face it, Im in flat mountainless Chicago with a MTB bike and I am 6'4" at 200lbs, I'll spin the cranks off with a dinky little 46T "big" ring.



    So, first and foremost, I dont care about shifting to the granny gear, I have a 50/34/24 and would really like to just stay in the 50/34.



    I ordered a new Shimano XTR "Shadow" derailleur but it wont be available till mid-late December anyway.... still, I should probably get the front derailleur , casette and shifters while Im waiting, but Shimano presents 3 different options, and Im unsure if any of them are going to work with anything larger then a 46T big ring anyway, but here go's....

    The FD M971



    and the FD M970 and e-type (smaller pic) front derailleurs.



    Whats the advantage, which one do I need and why? Will any work on a 50T (on the 50T alone even) or is there simply some sort of chain alignment part I could use instead, (similar to what some single speeders use to keep the rear in line)???

    Thank you for your help. This is where the bikes stand right now....





    Cheers
    Last edited by Call_me_Clyde; 11-10-2007 at 06:49 AM. Reason: To merge two threads by OP

  2. #2
    Keep The Rubber Side Down
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    the only thing I can add is to stay away from the "E" clamp derailleurs. I've had nothing but bad luck with those.
    Some of my happiest memories in life took place on my bicycles. - Me

  3. #3
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    Funny because Ive had bad luck over the years with any front derailleur that wasn't an e-Clamp. I had the old M951 with the Carbon e-Clamp (last product that was carbon on Shimano before the "Shadow" stuff IIRC). The issue with the e-clamp now is that I dont think it can be adjusted tall enough for a 50T ring, but I sure did like the looks and protection from chain suck with the old e-type system.

    I guess its really a choice between the 970 or 971, I dont really like the looks of the big X (looks like it should be on a prop for the next X-Men movie or something) but if it works better then the 970 for whatever reason, thats what I need to find out.

    In a perfect world I'd take the 970 if I was 100% it will work for my set-up. Guess, I should call a Shimano rep and see if I can get in touch with a tech.

    Thanks for responding.

    If anyone else has a definitive answer, Im all ears (so to "speak")

    Cheers.

  4. #4
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    Since no one has replied, I'll take my best guess based on my rather limited experience:

    The M970 probably won't work, it looks like the suspension link above the bottom bracket would force you to mount it too high.

    The e-type might work, but I'm not sure how height-adjustable it is. Given that the top of a 50-tooth ring will sit considerably higher than a 44-toother, I would bet against it.

    I'd go with the M971. You should be able to mount it to accommodate the big ring, and the 'X' on the swing arm looks cool! Whether it(or any other derailler) will handle the gap from the 50 to the 34, I don't know. You might want to upsize your other rings. Salsa makes them in a multitude of sizes.

    Try posting in the drivetrain forum, there's some smart folks over there.

  5. #5
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    Quote Originally Posted by Rufudufus
    The e-type might work, but I'm not sure how height-adjustable it is.
    Attaches with a bolt to a frame braze-on (or with an optional clamp), but I expect you all know that.

  6. #6
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    Thanks. I didnt know what the appropriate forum was, just picked Passion since it generally has the most viewers. I'll repost in the Drivetrain forum.

    You like that big ole X huh? cool.... I actually do my own line of products (cranks, posts, bars etc), so I could always plop a 36 middle and see if that would help.

    I appreciate the response.

    Cheers.

  7. #7
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    Repost: Help! Shimano is making my head hurt. Front Derailleur chat. Lots of pics....

    Copy & Paste from the Passion forum (I was instructed to post here instead)...


    Long story short, any MTB'ers know what kind of front derailleur I should go with?

    Heres my long post from the original thread. Thanks...

    Tryng to finish up my BMC Fourstroke and need a few more parts. One snag is the front derailleur. I mean, thanks Shimano, more choices are great, when they are better explained.... Unfortunately, model numbers and a price tag dont help when most of the resellers copy and paste the same blurb.

    A bit of background. I do the carbon cranks, yes, we all should know by now. My new Integrated Carbon Crank is 720g with an outboard Ti BB spindle and I took off a 50T chain ring from one of my compact cranks, because lets face it, Im in flat mountainless Chicago with a MTB bike and I am 6'4" at 200lbs, I'll spin the cranks off with a dinky little 46T "big" ring.



    So, first and foremost, I dont care about shifting to the granny gear, I have a 50/34/24 and would really like to just stay in the 50/34.



    I ordered a new Shimano XTR "Shadow" derailleur but it wont be available till mid-late December anyway.... still, I should probably get the front derailleur , casette and shifters while Im waiting, but Shimano presents 3 different options, and Im unsure if any of them are going to work with anything larger then a 46T big ring anyway, but here go's....

    The FD M971



    and the FD M970 and e-type (smaller pic) front derailleurs.



    Whats the advantage, which one do I need and why? Will any work on a 50T (on the 50T alone even) or is there simply some sort of chain alignment part I could use instead, (similar to what some single speeders use to keep the rear in line)???

    Thank you for your help. This is where the bikes stand right now....





    Cheers!

    New info, someone suggested I move the middle ring up from 34 to 36, someone else also said the 971 was the way to go, I gotta lot of homework to do Thanks again all.

  8. #8
    skillz to pay billz
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    "Im in flat mountainless Chicago with a MTB bike"

    Do you really need any front dérailleur? Just go big ring and call it good

  9. #9
    Rolling
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    This thread has too much bling for me.

    Gotta go with Nooby on this, the ultimate way to save weight.

  10. #10
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    Quote Originally Posted by lidarman
    This thread has too much bling for me.

    Gotta go with Nooby on this, the ultimate way to save weight.
    Yeah but then he wouldn't have had an excuse to inpress us with all of his toys. I mean, how long did it take for Shamu to jump into that one shot?

    Seriously though OP, I feel your pain having just purchased a lowly LX front der for my commuter.

  11. #11
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    Quote Originally Posted by nOOby
    "Im in flat mountainless Chicago with a MTB bike"

    Do you really need any front dérailleur? Just go big ring and call it good
    When I hang onto a semi doing 50 mph and hit the viaduct ramp, that chain doesnt always stay put

  12. #12
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    Quote Originally Posted by dir-T
    Yeah but then he wouldn't have had an excuse to inpress us with all of his toys. I mean, how long did it take for Shamu to jump into that one shot?

    Seriously though OP, I feel your pain having just purchased a lowly LX front der for my commuter.
    Shamu is a whale, thats a shark on my TV

    You really think LX would go better with this build?

  13. #13
    Rolling
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    Quote Originally Posted by dir-T
    Yeah but then he wouldn't have had an excuse to inpress us with all of his toys. I mean, how long did it take for Shamu to jump into that one shot?
    .

    CarbonLORD looks to live in the house the American Psycho.

  14. #14
    Mantis, Paramount, Campy
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    Of The Options Presented...

    The 971 is the way to go.

    Why not DA or Ultegra?

    EDIT: Oh right...stupid top pull derailleurs!!

    You could still mod an Ultegra or Campy road f derailleur to top pull and use that. And as a bonus if you use a Record you'd get even more carbon
    *** --- *** --- ***

  15. #15
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    Quote Originally Posted by carbonLORD
    You really think LX would go better with this build?
    Absolutely! You're fine with the cranks but you don't want road salt eating away at a fancy deraileur.

    Mail me the TV and I'll send you my der and will even throw in the used 700cx23 tires that are hanging in my garage. Deal?

  16. #16
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    Quote Originally Posted by lidarman
    CarbonLORD looks to live in the house the American Psycho.
    Absolutely. Its funny, I had not even seen that movie until after I bought the place last season, and you would be the 4th person to reiterate that very same comment.

    Its now one of my more favorite movies...... similar indeed

  17. #17
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    I wouldn't move out either...

    if my mom had a sweet tv like that

  18. #18
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    With a big 50t big ring like that, I'd have a look at shimano's road front derailleurs. You may have to watch out for chainline issues though.

  19. #19
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    Quote Originally Posted by Micka
    With a big 50t big ring like that, I'd have a look at shimano's road front derailleurs. You may have to watch out for chainline issues though.
    I was thinking the same thing Micka, but I think carbonLORD might run into issues with the road der. being able to accommodate the 24T granny. Personally, if the OP thinks a 50T big ring is really needed, I would scrap the granny and run a 2X9. I think that setup would play better with a road front der.
    Quote Originally Posted by turnerbikes
    in fact for trail type bikes I am tired of QR roady shite in general. Lets move on.

  20. #20
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    Sorry to make your head hurt Mr. Lord. Here are some fun facts that might help make an informed decision about which derailleur you would like to try. First though, I should mention that there is no derailleur that is designed to shift those gears so it's good that you said you don't care about shifting into the granny gear. You will also have problems shifting from the 34 to the 50.

    16 teeth is a huge gap to bridge and any derailleur will have a hard time doing that. We get away with it on compact road cranks by using very complex ramps on the inside surface of the large ring that grab the chain and help pull it up and guide it back down. It's the quality of these ramps that sets our compact crankset chainrings apart from others (shameless plug).

    Each derailleur has a spec for maximum large ring size, max difference between large and small rings, max difference between large and mid rings and chain wrap capacity. Your setup exceeds all of these specs.

    No MTB front derailleur is rated to work with a 50 tooth big ring. The max ring size for all new XTR derailleurs is 44 teeth. XT/LX/Deore non E-type FDs have a max ring size of 48 teeth because they have to work with the touring editions of those cranks that use 48-36-26.

    *Note* this touring gear ratio is what we have designed for someone with your needs and this will be the closest to what you want with Shimano quality shifting.

    Using an MTB FD with a 50T big ring will force you to mount it higher than normal so the cage will clear the big ring. Since the arc of the outer cage plate is designed to match the curvature of the max chainring size you will have to mount it even higher so that the trailing edge of the derailleur doesn't graze the teeth. This is going to make the front shifting pretty slow because the bumps on the cage plates that push the chain up and down will not be in the right place to hit the chain.

    That 16 tooth difference exceeds the spec of the max difference between large and mid rings for all MTB derailleurs which can handle a maximum of 12. Even road derailleurs have a spec of 15 which is why compact road cranks are so hard to get to shift right and why those ramps are so important.

    The 26 tooth difference between your large and small rings exceeds the max spec on all MTB FDs of 22 teeth. This means that the chain would rub on the pin that connects the inner and outer cage plates at the trailing edge of the derailleur when you are on the small ring and the smaller gears on the cassette.

    Road and MTB front shifters/derailleurs use a different cable pull ratio so you can not use a road FD with a MTB shifter.

    Using an 11-34 cassette you would require a chainwrap capacity of 49. The largest capacity of any Shimano rear derailleur is 43. This means that if your chain were long enough to not rip the derailleur of the bike in the 50/34 combo it would droop in half the gears when using the small ring.

    The E-type FDs will not mount anywhere near high enough to clear a 50 tooth ring.

    To choose between the M970 and M971 the basic rule of thumb is that you always use the top swing (M970) unless your frame prevents you from mounting it. The M970 is slightly stiffer which is why it gets the nod when you could go either way.

    So I know that probably made your head hurt even more but at least you have that elusive tech info now. If this were my bike I would pick up some XT rings in the 48-36-26 ratio and use the new M770/771 front derailleur. That way your shifting would be awesome and you would only be giving up two teeth.

    Hope that helps.

  21. #21
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    Sorry to make your head hurt Mr. Lord. Here are some fun facts that might help make an informed decision about which derailleur you would like to try. First though, I should mention that there is no derailleur that is designed to shift those gears so it's good that you said you don't care about shifting into the granny gear. You will also have problems shifting from the 34 to the 50.

    16 teeth is a huge gap to bridge and any derailleur will have a hard time doing that. We get away with it on compact road cranks by using very complex ramps on the inside surface of the large ring that grab the chain and help pull it up and guide it back down. It's the quality of these ramps that sets our compact crankset chainrings apart from others (shameless plug).

    Each derailleur has a spec for maximum large ring size, max difference between large and small rings, max difference between large and mid rings and chain wrap capacity. Your setup exceeds all of these specs.

    No MTB front derailleur is rated to work with a 50 tooth big ring. The max ring size for all new XTR derailleurs is 44 teeth. XT/LX/Deore non E-type FDs have a max ring size of 48 teeth because they have to work with the touring editions of those cranks that use 48-36-26.

    *Note* this touring gear ratio is what we have designed for someone with your needs and this will be the closest to what you want with Shimano quality shifting.

    Using an MTB FD with a 50T big ring will force you to mount it higher than normal so the cage will clear the big ring. Since the arc of the outer cage plate is designed to match the curvature of the max chainring size you will have to mount it even higher so that the trailing edge of the derailleur doesn't graze the teeth. This is going to make the front shifting pretty slow because the bumps on the cage plates that push the chain up and down will not be in the right place to hit the chain.

    That 16 tooth difference exceeds the spec of the max difference between large and mid rings for all MTB derailleurs which can handle a maximum of 12. Even road derailleurs have a spec of 15 which is why compact road cranks are so hard to get to shift right and why those ramps are so important.

    The 26 tooth difference between your large and small rings exceeds the max spec on all MTB FDs of 22 teeth. This means that the chain would rub on the pin that connects the inner and outer cage plates at the trailing edge of the derailleur when you are on the small ring and the smaller gears on the cassette.

    Road and MTB front shifters/derailleurs use a different cable pull ratio so you can not use a road FD with a MTB shifter.

    Using an 11-34 cassette you would require a chainwrap capacity of 49. The largest capacity of any Shimano rear derailleur is 43. This means that if your chain were long enough to not rip the derailleur of the bike in the 50/34 combo it would droop in half the gears when using the small ring.

    The E-type FDs will not mount anywhere near high enough to clear a 50 tooth ring.

    To choose between the M970 and M971 the basic rule of thumb is that you always use the top swing (M970) unless your frame prevents you from mounting it. The M970 is slightly stiffer which is why it gets the nod when you could go either way.

    So I know that probably made your head hurt even more but at least you have that elusive tech info now. If this were my bike I would pick up some XT rings in the 48-36-26 ratio and use the new M770/771 front derailleur. That way your shifting would be awesome and you would only be giving up two teeth.

    Hope that helps.

  22. #22
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    Do what BMC do...



    M971

    If you choose MTB sized chain rings. But despite what's been said (ie how that 16t gap is to big), I'd imagine that an M971 wouldn't work with a 50t chainring because of the gusset for the ST pivot.

  23. #23
    CAN YOU DIG IT??!!??!!!??
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    WOW !!!! Hey Shimano Ride Support, are you here representing Shimano or are you just here as a rider???
    "Why are you willing to take so much & leave others in need...just because you can?"

  24. #24
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    re: shimano front derailler specs

    i tink that answers the questions and then some!

    Would not some of the 'oldschool' 110 BCD front deraillers work fairly well too (I know, we're still exceeding the rated capacities btw rings)? eg - 900/950ish xtr, 735ish xt.
    Not that these would look right on the 'LORD's bike
    [SIZE=1][/SIZE]

  25. #25
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    Quote Originally Posted by Shimano Ride Support
    Sorry to make your head hurt Mr. Lord. Here are some fun facts that might help make an informed decision about which derailleur you would like to try....

    Hope that helps.

    Thank you so much. This is exactly the kind of technical post I was hoping for! I might just ditch the 50T dream and put the 46 back on.... Be nice if I could run a road FD (Record Compact) and run the compact 50/36 option, but my manufacturer doesnt have a 110mm BCD 38 middle or a 48 for that matter so Im stuck playing with the cards I am dealt...

    On a side note, Ive probably sold around a few hundred compact cranks and the feedback Ive received has always indicated a "compact" specific road front derailleur was not necessarily required. I realize from your response that shifting delays might be the outcome of running a standard FD on a compact gear ratio, just putting that out there... I usually recommend my customers try it with their existing set-up, when they do make the switch to compact, and theres usually no issues.

    I think I'd like to try some sort of a 2x9 set up. I was planning on going with the tighter 11/32 cassette, and the "Shadow" RD is supposed to be a GS cage as Shimano doesnt manufacture a short cage version for the "shadow". Is there any benifit in running a 2x9 set up this way or am I better off just keeping the granny on there so the chain would'nt accidentally drop?

    I do appreciate the response, really. Its a shame I cant run that 50T without barriers, but if it wasn't meant to be, it wasn't meant to be....... On a side thought, what are downhillers running these days...?

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