11-32 di2 - need the 6870 RD long?

petelars

Issue: Mountains. Lots of them. Next summer.

Gear presently available: Focus Cayo Evo 2 with Ultegra Di2, 10 speed (6770).

I rode the alpe and telegraphe this summer with a 11-28 casette, and I really struggled with pentes over 9%. So, I figured I'd get fitter and lighter, as well as acquire a wider range of gears for next year's ride. Ultimately, I want to ride La Marmotte.

As far as I know, the 6770 rear derailleur is only available in short form, i.e. up to -28 (with luck -30) casettes. I have seen references to the 6870 series having a long rear derailleur available though, which'll take the 32 casette. Question is, what do I need to make the switch?

Front derailleur
Rear derailluer
Casette
Chainrings
Chain

all from the 6870 series?

As far as I know, the shifters and brakes are ok, as is the wiring and control box. I guess the firmware would need to be upgraded, too?

DHA987S

I think you should be able to run it without chainrings but you will need the other bits you list. The shifters WILL work with the new front and rear mechs, they are just switches and don't determine any thing such as number of cogs on the rear etc. Firmware would need upgrading.

Do you have an 11speed wheelset? You will need that as well.

apriliarider

Why not consider getting a cheap(er) compact chainset for the front just for when you need it ?

Just Googled - apologies if it has one already - if it has then train specifically for the event and shed as much weight as possible and you will see a big difference in your climbing

Cheers

petelars

I started out at 100 kg last summer, even though I commuted 20 km each way by bike, to work. Began working harder at biking, watching what I ate (and added a colleague who's training for an Iron Man, that's a great source of inspiration), and I was 85 when I biked in the Alps this summer, and am presently at 83.

I plan to be at 75 kg next summer, and almost more importantly , I've shed a lot of weight off my bike, too. FSA cast iron cockpit/seatpost has been replaced by 3T carbon. With pedals, helmet, I think it comes to about half a kilo, all told.

Additionally, I've bought a bkool home trainer, so I can train all winter, with a focus on climbing. That'll help me figure out of a bigger cassette is really needed.

I have two wheelsets, Cosmic Carbone SLs from this year, and Dura Ace C24 7900s. I think the big spacer on the Cosmics means it'll take 11 speed, but I'm not sure. I'd obviously prefer to ride the C24s (lighter).

petelars

Twist: Is it possible to rebuild the RD with the longer drop from a 6700 GS RD? Cannibalize the 6700 RD, I mean, and mod the 6770 as a longer one?

Rodrego Hernandez

It is possible to swap the cages over.

Stick a compact on - if you can't get up those hills in 34x32 then it may be better to sell the bike and take up golf.

Lose the 11t sprocket and get a 12 or 13 up, smaller jumps between sprockets will make for a more comfortable ride and a better choice of gears when climbing.

Best bet though really is to get fit, lose some weight and train properly for it.

petelars

I'm training too, not to worry. Weight is coming down nicely, though obviously it's a struggle to BOTH train and drop weight. Balancing carbs is a bit tricky.

It FEELS like I've jumped a level or two since July, in terms of sustained power output. I'll get a better idea once the summer wears off, and I get to spend some time with the hometrainer / spinning.

I wholeheartedly agree, btw. If a 34x32 doesn't do it, nothing will.

Off to the lbs, to hear if they're up to modding the RD...