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Front Mech Replacement, old Suntour is dead

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Front Mech Replacement, old Suntour is dead

Old 07-26-22, 10:45 AM
  #1  
elston1999
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Front Mech Replacement, old Suntour is dead

I have a cannonade r500 with a suntour front mech and it is about gone. I have read that many front mechs are interchangeable. IE:7,8,9 speed. It is a 3x7. Would any of the 7,8,9 triple front mechs work (sora, claris, etc)? I do ride quite a bit. I have micronew sti shifters if that helps with recommendations. Thanks community!!
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Old 07-26-22, 10:53 AM
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Can you post the chainring sizes on the triple? Can impact recommendations a little- a half step + granny (i.e. 48-44-30) might not work great with a triple cage for instance. Usually triples have gaps of about 10-12 between the largest two chainrings and 10-12 on the smaller which line up with the front derailleur cage (i.e. 52-42-30, 50-40-30, 48-38-28, etc) - more on cages below.

And the old Suntour - is it a triple specific FD with a deeper/taller cage and a channel for the middle? Or more of a double / do it all with flat sides? I've attached some pictures of the cage types. What's your mounting type - direct, band (31.8?).


Double Cage

Triple Cage
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Old 07-26-22, 12:52 PM
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I replaced my suntour mountech with an old cyclone FD, shifts a half-setp+granny no issue
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Old 07-26-22, 01:19 PM
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Personally this resonates with me cause I am going thru FD Hell trying to find any clamp-on FD that works with a bastardized half-step/granny triple on an '80s Univega Activa Trail.

I've built dozens if not hundreds of frames with used parts and never experienced so much of an incompatibility issue: tried out at least a dozen different FDs, all kinds of cage types, not a one worked "well" but the one that came closest was a vintage Shimano 600 road type (double with narrow cage).

I think the big headache is that I had a functional Shimano trigger shifter/lever combo (triple) that I have given up on, now. The matching 7-spd combo for RD shifts the 13-28 rear without a hitch but now scraping the pair in favor of something (TBD) with friction shifting for the FD.

Note that I find many of the "modern" Shimano FDs (Sora, Claris, etc.) which are labeled for a particular index range (such as for "9-speed") are not happy to play well with some other system. The throw they produce to index with a matching shifter makes them unlikely to do the same with say a FD shift unit from a 7-or-8 speed shifter set.
At least this is my working theory for the moment.

Last edited by unworthy1; 07-26-22 at 01:26 PM.
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Old 07-26-22, 01:34 PM
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chainring is 52/42/30 but that likely needs replaced now. I was counting the rings and saw that many of the teeth are worn or even gone.
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Old 07-26-22, 01:39 PM
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[QUOTE=AJI125;22588265]Can you post the chainring sizes on the triple? Can impact recommendations a little- a half step + granny (i.e. 48-44-30) might not work great with a triple cage for instance. Usually triples have gaps of about 10-12 between the largest two chainrings and 10-12 on the smaller which line up with the front derailleur cage (i.e. 52-42-30, 50-40-30, 48-38-28, etc) - more on cages below.

And the old Suntour - is it a triple specific FD with a deeper/taller cage and a channel for the middle? Or more of a double / do it all with flat sides? I've attached some pictures of the cage types. What's your mounting type - direct, band (31.8?).

chainring is 52/42/30 but that likely needs replaced now. I was counting the rings and saw that many of the teeth are worn or even gone.
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Old 07-27-22, 03:36 PM
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Originally Posted by unworthy1 View Post
Personally this resonates with me cause I am going thru FD Hell trying to find any clamp-on FD that works with a bastardized half-step/granny triple on an '80s Univega Activa Trail.

I've built dozens if not hundreds of frames with used parts and never experienced so much of an incompatibility issue: tried out at least a dozen different FDs, all kinds of cage types, not a one worked "well" but the one that came closest was a vintage Shimano 600 road type (double with narrow cage).

I think the big headache is that I had a functional Shimano trigger shifter/lever combo (triple) that I have given up on, now. The matching 7-spd combo for RD shifts the 13-28 rear without a hitch but now scraping the pair in favor of something (TBD) with friction shifting for the FD.

Note that I find many of the "modern" Shimano FDs (Sora, Claris, etc.) which are labeled for a particular index range (such as for "9-speed") are not happy to play well with some other system. The throw they produce to index with a matching shifter makes them unlikely to do the same with say a FD shift unit from a 7-or-8 speed shifter set.
At least this is my working theory for the moment.
Friction shift is the ONLY way to go for the front derailleur. (Or the rear, in my opinion.)
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Old 07-27-22, 11:15 PM
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^ that's my current solution and it solved the problem just fine! I had a set of Shimmy thumb shifters that retain the 7S indexing for the rear but have friction for the front. Adding a "9S" Tiagra FD with a double cage (to shift a triple) everything works like a champ!
I am gonna leave well enough alone!
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Old 07-28-22, 08:18 AM
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So for a standardish triple as you note (if you go with similar rings), I've used a Shimano CX-70 (10 speed chain/crank setup, 10 speed Campy left shifter), Shimano FD-5503 triple front (9 speed chain/crank setup, 9 speed Shimano STI left shifter), and Suntour SL (8 speed chain, friction). I found going outside the standard triple ring spaces (i.e. half step or big drops) didn't work well for me with triple cages (as pictured above) due to where that center channel lines up, it wants about 10-12 teeth below the big ring for the middle, otherwise the cage is really skinny in the middle outside of that channel.

My Fuji setup now is half step (53-49-36) with the Suntour SL and 8-speed chain on friction barcons, works well (getting the 53 to drop to the 49 takes a bit of feel, if I don't ride the bike for a while it can seem finicky).

I've read anecdotal info that Shimano 600 era double FDs with fairly straight side cages (and I assume the same era 105s) work pretty well for a range of triples and compact doubles as well as their original specs. But as noted I think getting the right combination for your shifter and crank (and bike clearances) can sometimes take some fiddling. I'd definitely go with something cheap off eBay, here, local co-op, or Craigslist/Facebook to see if it works before getting something NOS or fancy!
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Old 07-28-22, 04:46 PM
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I've happily used Suntour Vx and Gen 1 Cyclone to shift 45/42/28. Have you considered a used Suntour FD from an auction or classified ad site?
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