Converting a compact to a sub-compact chain ring

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slogfester
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Real Name: Barry Evans
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Converting a compact to a sub-compact chain ring

Post by slogfester » 07 Mar 2017 09:53

One for you techie people.

I would like to convert my pommie bike (2013 Van Nicholas Yukon c/w 11 spd Ultegra 6800 groupset, compact 34-50 / 11-28) to take my new 2016 (Dura Ace 9000) sub compact 36-52 chain ring (which has a dual sided 4iiii power meter fitted). Easy, just swap the chain rings (and fit new longer chain), but I'll need more than the resulting 36 x 28 to get my lardy arse up Windwoodheath road! Ideally I'd like a 11-32 on the back, the same as my Aussie bike. But I fear that my 6800 RD wont take it? I'm pretty sure it has the standard 'short SS' cage on it. So what are my options? Presumably easiest would be to fit the new 12-32 cassette (plus new longer chain of course) and see if the SS will handle it? Next step if that doesn't work? Can I fit a longer cage to a 6800? And/or will that require a longer drop out too? Errr.... I think the ti frame doesn't have changeable drop outs???

Or maybe just get the 6800 GS ('medium cage') currently a steal at 50 pommie pesos on wiggle and guaranteed to work up to 32 rear cog?

Having ridden Ultegra 6870 Di2 for 6 months here DownUnder, I wouldn't take much convincing to upgrade my pommie bike to Di2. I never liked the cable routing on the mechanical 6800. But that would require new levers, an ungainly un-Audax battery etc etc. Plus, it looks like you have to buy a complete groupset with the SS RD and then swap to the GS RD? More pommie pesos!

Comments and suggestions if you please.
Belt up, we're going for a ride

George L
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super compact

Post by George L » 09 Apr 2017 07:39

Hi

Go On FSA website they now do a super compact with 48 30 tooth.

So you can run a better closer ratio rear cassette without the stupid large jumps of a fry pan cassette.

George

laurence_cooley
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Post by laurence_cooley » 09 Apr 2017 08:28

The 6800 medium cage mech has a maximum capacity of 41, so you could run a 11-32 with that. The capacity of the short cage version is 33, so I think you'd be pushing it with the existing one.

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jdtate101
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Post by jdtate101 » 09 Apr 2017 19:02

Yep 6800 can easily take a 32T rear cassette. Dura ace is the only one with a max of 28, but even that can be taken to 32 with a bit of bodging.

slogfester
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Joined: 10 Oct 2009 13:12
Real Name: Barry Evans
Location: Birmingham

Re: Converting a compact to a sub-compact chain ring

Post by slogfester » 22 May 2017 09:32

Happy to report that this was a straight forward swap. The b-screw on the 600 GS RD only half way in, so it looks like the Yukon frame could if needed take a monster gear.

If I can do it, anyone can! Result is a do-anything silky-smooth 36/52 x 11-32: what's not to like?
Belt up, we're going for a ride

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