11-28 to 11-34 road bike upgrade : Update !

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audaxjk
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Joined: 2 Mar 2020, 4:45pm

11-28 to 11-34 road bike upgrade : Update !

Post by audaxjk »

Hi

I am about to build up a cyclocross frame with a virtually new Ultegra 6700 Groupset I have in the garage (with a SRAM rival 48/34 chain set).

The Groupset has an 11-28 cassette & a 6700 short cage derailleur. Ideally, I would like to go to 11-34 on the new build. I know that I’ll need to add a few chain links in addition to the new cassette, but beyond this what workable options are there?

Would the short cage mech work either as it is or with a road link type extender, and if not, would a 6700 GS (med cage) mech be ok? I am aware that Shimano’s RD 6700 manual quotes a total derailleur capacity of 33T for the SS and 39T for the GS
Last edited by audaxjk on 22 Jul 2022, 5:13pm, edited 1 time in total.
hamster
Posts: 4128
Joined: 2 Feb 2007, 12:42pm

Re: 11-28 to 11-34 road bike upgrade

Post by hamster »

You could try a mech dropper, alternatively an MTB 9 speed rear mech, which is cross-compatible with road 10 speed.
keyboardmonkey
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Joined: 1 Dec 2009, 5:05pm
Location: Yorkshire

Re: 11-28 to 11-34 road bike upgrade

Post by keyboardmonkey »

I run a 6700 GS with a 11-34 cassette on one bike. Better still is a ‘Shadow’-style 9-speed MTB mech that I have on another bike (mine is a Deore XT M772, but they are not readily available these days).
audaxjk
Posts: 155
Joined: 2 Mar 2020, 4:45pm

Re: 11-28 to 11-34 road bike upgrade

Post by audaxjk »

Thanks for the replies above. I never considered a 9 speed mtb mech - wasn’t aware it would be compatible!

Can I ask you keyboardmonkey why you think it’s better than the 10 speed GS 6700?
hamster
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Re: 11-28 to 11-34 road bike upgrade

Post by hamster »

The MTB mech is designed for a wider-range cassette, unlike the road one.
audaxjk
Posts: 155
Joined: 2 Mar 2020, 4:45pm

Re: 11-28 to 11-34 road bike upgrade

Post by audaxjk »

Thinking about your replies, can I also ask why a 9 speed mtb rear derailleur as opposed to a 10 speed mtb one (considering that the road Groupset is a 10 speed?)
rareposter
Posts: 1964
Joined: 27 Aug 2014, 2:40pm

Re: 11-28 to 11-34 road bike upgrade

Post by rareposter »

audaxjk wrote: 19 May 2022, 2:14pm Thinking about your replies, can I also ask why a 9 speed mtb rear derailleur as opposed to a 10 speed mtb one (considering that the road Groupset is a 10 speed?)
It's to do with cable pull ratios. A 9sp Shimano MTB mech works with 10sp Shimano road shifters because the cable pull for 10sp road is the same as for 9sp MTB. I've got a 9sp XTR mech on my CX bike - ran it with 10sp Ultegra STI for a long time then swapped to 10sp GRX levers which happily still use the same ratio!

Edit - mine is running an 11-36 10sp cassette.
keyboardmonkey
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Joined: 1 Dec 2009, 5:05pm
Location: Yorkshire

Re: 11-28 to 11-34 road bike upgrade

Post by keyboardmonkey »

audaxjk wrote: 19 May 2022, 2:14pm Thinking about your replies, can I also ask why a 9 speed mtb rear derailleur as opposed to a 10 speed mtb one (considering that the road Groupset is a 10 speed?)
The “pull” for 10-speed MTB rear mechs is different from the pull on 10-speed road mechs*.

To be clear, the pull on 9-speed road, 9-speed MTB and 10-speed road is the same, *except for 10-speed Tiagra 470x series, which is the same as 11-speed road. Phew.

In answer to the difference between 6700 GS and M772 GS, the 10-speed Ultegra rear mech is, technically, operating outside its specified limit in my 11-34 setup, whereas the Deore XT M772 rear mech is comfortably within it. Both work *for me*, but the M772 is slicker.
Psamathe
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Joined: 10 Jan 2014, 8:56pm

Re: 11-28 to 11-34 road bike upgrade

Post by Psamathe »

Different Shimano groupset but my experience of exceeding Shimano's specs.

https://psamathe.net/shimano-4703-groupset-review/

Ian
iandusud
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Joined: 26 Mar 2018, 1:35pm

Re: 11-28 to 11-34 road bike upgrade

Post by iandusud »

I've got a short cage 6700 rear mech on my winter bike with a 50-34 chainset and 11-32 cassette. It works well but it lacks the capacity to avoid a slack chain if you use the smallest sprockets when on the small chainring. However in practice this isn't a problem. So you would be running the same capacity as I am with your setup. You might need a hanger extender to clear the 34t sprocket but I think it should work.
audaxjk
Posts: 155
Joined: 2 Mar 2020, 4:45pm

Re: 11-28 to 11-34 road bike upgrade

Post by audaxjk »

Many thanks to you all.

Having mulled over all the great advice given, I like the idea of the MTB mech and may as well go for an 11-36 cassette with this option rather than an 11-34. This should give me all the gearing I should ever need for my riding with a bit to spare as I get (even) older! I'm determined to go back and do the Fred Whitton again and this time get over the two 30+% hairpins on Hardknott without unclipping!
Valbrona
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Joined: 7 Feb 2011, 4:49pm

Re: 11-28 to 11-34 road bike upgrade

Post by Valbrona »

But Shimano MTB mechs do not have cable adjuster.
I should coco.
rareposter
Posts: 1964
Joined: 27 Aug 2014, 2:40pm

Re: 11-28 to 11-34 road bike upgrade

Post by rareposter »

Valbrona wrote: 19 May 2022, 9:16pm But Shimano MTB mechs do not have cable adjuster.
Because they don't need one. You can just pull the cable through a fraction if it has stretched after first installation or you can incorporate those little inline cable adjusters - something like this:
https://www.edinburghbicycle.com/shiman ... e-adjuster

Plus the cable adjuster (or lack thereof) has no bearing on whether the mech will work with the cassette and shifters.
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Mick F
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Location: Tamar Valley, Cornwall

Re: 11-28 to 11-34 road bike upgrade

Post by Mick F »

Yep.
Fit an inline adjuster.
I have a Deore XT on my Moulton and as that mech doesn't have an adjuster, I fitted one of these.
https://www.wiggle.co.uk/token-tk684-al ... r-grappler
Screen Shot 2022-05-20 at 08.07.21.png
Screen Shot 2022-05-20 at 08.07.21.png (84.32 KiB) Viewed 624 times
Mick F. Cornwall
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fausto99
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Joined: 19 Sep 2011, 10:06am
Location: NW Kent

Re: 11-28 to 11-34 road bike upgrade

Post by fausto99 »

Rareposter's suggestion is very expensive, MickF's is out of stock at Wiggle, so, you might try this https://www.wiggle.co.uk/lifeline-cable ... igodigital.
I have one on one of my bikes. It works OK.
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