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  #1  
Old 06-28-2016, 06:25 AM
ontarget ontarget is offline
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Cross crankset on road bike - front derailleur height adjustment

I recently purchased a Specialized Roubaix frame from a member of this forum. I intend to build it up with Ultegra 6800 and would like to run a 11-28 or 11-32 cassette. The fact is, I have no use for a 50-11 high gear. On another bike (with band-type front derailleur) I went with a cross crankset (46/34) and find that the 46T large ring is far more useful for me.

Before I order a cross crankset I'm curious if the slot in the braze-on will allow me to get the front derailleur low enough to run a 46T big ring. Anyone have experience with this?

Thanks.
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Old 06-28-2016, 06:35 AM
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oldpotatoe oldpotatoe is online now
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Quote:
Originally Posted by ontarget View Post
I recently purchased a Specialized Roubaix frame from a member of this forum. I intend to build it up with Ultegra 6800 and would like to run a 11-28 or 11-32 cassette. The fact is, I have no use for a 50-11 high gear. On another bike (with band-type front derailleur) I went with a cross crankset (46/34) and find that the 46T large ring is far more useful for me.

Before I order a cross crankset I'm curious if the slot in the braze-on will allow me to get the front derailleur low enough to run a 46T big ring. Anyone have experience with this?

Thanks.
Really doubt it. Is the brazeon tab bolted onto the frame? If so, maybe Spec. makes a longer tab..like Trek does.
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Old 06-28-2016, 06:42 AM
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AngryScientist AngryScientist is offline
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pro-tip: if you use a triple FD, you can mount the fd a little higher than you normally would and it will shift fine.
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  #4  
Old 06-28-2016, 07:45 AM
gt eunuch gt eunuch is offline
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I came across this the other day, and it seems like this could be the perfect application for it (barring it doesnt sit the FD too low). I have never used it, but WickWerks makes solid products, and it isnt too expensive!

https://wickwerks.com/products/fit-link-adapter/

Last edited by gt eunuch; 06-28-2016 at 07:49 AM.
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Old 06-28-2016, 08:20 AM
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Lewis Moon Lewis Moon is offline
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From my "back of the envelope" estimation, if you have ~1cm of slot below the bolt with the derailleur properly positioned for the 50, you should be golden.
Of course, I could be totally wrong, and often am.

What type of cassettes are you on? Is there a chance you could find a "junior" cassette that starts at 13? There's nothing magic about an 11.
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Old 06-28-2016, 08:22 AM
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or just hand build a cassette with the gears you want
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Old 06-28-2016, 08:25 AM
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wallymann wallymann is offline
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Quote:
Originally Posted by gt eunuch View Post
I came across this the other day, and it seems like this could be the perfect application for it (barring it doesnt sit the FD too low). I have never used it, but WickWerks makes solid products, and it isnt too expensive!

https://wickwerks.com/products/fit-link-adapter/
neat product! looks like a real problem-solver.

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Last edited by wallymann; 06-28-2016 at 08:31 AM.
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  #8  
Old 06-28-2016, 09:11 AM
ontarget ontarget is offline
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The WickWerks option is interesting, though from my reading it looks like it may lower the FD too much, as it's designed for an even smaller chainring than 46T.

I looked at junior cassettes, but the only one I found is 14-28. That's not high enough with a 34-50 crankset. (I'm tough to please!)

As for custom cassettes, I'll have to see what options I have, though with cogs riveted together onto carriers I may be limited in this regard.

I may just have to mount a 34-50 crankset that I have, position the FD, and see how much room I have to lower it. My calculations show that I'll have to move the FD about 8mm lower switching from 50T to 46T.
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Old 06-28-2016, 09:32 AM
gt eunuch gt eunuch is offline
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http://bbbcycling.com/bike-parts/cassettes/BCS-11S

another option, they have some crazy gearing choices, including an 18-28 (frame clearance may suffer on this though? How many frames can hold a 18 in the outboard position?)
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Old 06-28-2016, 12:39 PM
11.4 11.4 is offline
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Not trying to derail your approach, but the issue isn't whether you need a 50/11, as much as whether you like riding a 50 x 13,14,15,16,17,18,19,21 etc. Those are the gears that determine whether a 50 is right for you. Similarly, your 34 may be used mostly with your 12, 13, 14, and so on.

I've ridden a couple bikes with the Wickwerks adapter. On both it barely works with a 44 front ring. It does throw in a little bit of flexibility into the shifting system, not enough to really feel it with manual shifting but definitely with Di2.
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  #11  
Old 06-28-2016, 01:29 PM
gt eunuch gt eunuch is offline
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Quote:
Originally Posted by 11.4 View Post
Not trying to derail your approach, but the issue isn't whether you need a 50/11, as much as whether you like riding a 50 x 13,14,15,16,17,18,19,21 etc. Those are the gears that determine whether a 50 is right for you. Similarly, your 34 may be used mostly with your 12, 13, 14, and so on.

I've ridden a couple bikes with the Wickwerks adapter. On both it barely works with a 44 front ring. It does throw in a little bit of flexibility into the shifting system, not enough to really feel it with manual shifting but definitely with Di2.
Just curious, what does 'barely works' here mean? meaning it puts the FD barely too low, barely too high?
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  #12  
Old 06-28-2016, 02:10 PM
cachagua cachagua is offline
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If there's room for it in the derailleur you're going to use, you might drill & tap a second hole higher up. Check that you'll get enough engagement between the tab & derailleur, before committing, though -- hold it up there first and see what it looks like.

Or, grind the tab off the frame and use a clamp-style derailleur.

One caution: I put a 46-tooth ring on a bike recently and found that the derailleur's cage hit the chainstay -- had to use a different one. Make you've got room to move the thing down as far as you want!

Ditch the derailleur and go single-chainring? C'mon, all the cool kids are doing it...
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  #13  
Old 06-28-2016, 02:17 PM
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vqdriver vqdriver is offline
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erm, i'd just try it with the existing fd location.
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  #14  
Old 06-28-2016, 02:27 PM
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Originally Posted by vqdriver View Post
erm, i'd just try it with the existing fd location.
Agreed, I bet it will work.
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  #15  
Old 06-28-2016, 02:28 PM
ColonelJLloyd ColonelJLloyd is offline
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One of the reasons I'm against braze on FDs.
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