DMC707

Started this thread in the "Road Bike" sub forum but didnt get much outside of general knowledge

I have a newly built bike with a nice D-A 7800 group . cassette is either 11-27 or 12-27. Crankset is 53-39. Crankset was a custom ordered 165mm crankset so unless absolutely necessary i dont want to change it -- plus in a sea of black componentry, i really like the way the modern (ish) frameset looks with the anodized stuff now that its put together

But will a Wolftooth Roadlink allow use of a 12-32 cassette with the current crankset?

Thx in advance


New road bike - could use some gearing help/suggestions - Bike Forums

Bill Kapaun

You are already at maximum take up capacity.
You would have to lengthen the chain to match the largest cog/ring.
That will result in severe chain sagging on the smaller cogs/rings.

DMC707

with stock equipment - yes i am aware

why i was asking if that is in range of do-able with the Wolftooth Roadlink

bboy314

The roadlink will let you hit lower gears on your cassette but will have no effect on the total capacity of the derailleur.

rccardr 

So…data point. I’ve used up to a 30 tooth rear cog on my 7800 stuff, BUT with a 48/34 compact crank.
Not sure how happy it will be with a larger chainring AND larger cog.
Worth trying the Wolf Tooth.

Atlas Shrugged

There was a long cage model of that derailleur made and probably worth the money of picking one up on eBay. If lucky might find a well worn one for cheap and just use the cage. Also perhaps find a Ultegra GS and use that cage. Wolftooth does not increase capacity and that will be your issue.

I have swapped cages on both my Dura Ace Di2 and GRX to increase their capacity.

DMC707

in that time period, there was a non series crankset that was compact and matched the D-A stuff in appearance close enough

But tough to find now that were 12 or so years down the road.
Worth a shot as this gear ratio would do all I need

maddog34

From the web... the DA 7800 Shifter "... will work with shifters(and ders!) that use Shimano's new road pull ratio, which is anything GRX (10 or 11-speed), anything 11-speed, and Tiagra 4700 10-speed." (the shifters and Derailleurs mentioned are compatible)

i'd swap on a DA long cage, 11 sp.DA long cage Der.(either of those options, WITH a tooth), or the 11 sp. GRX Der, Max of 34T, so no tooth needed....
i'd guess that the 10sp. GRX is also an option, and most likely also capable of 34 tooth low gears.

the GRX with no tooth needed would be my choice.
and the Tiagra Ders come up for CHEAP on local sales pages... that line works fine (my Fuji CF road burner runs it) but the pull ratio change and some clunky brifters cursed the series...........

reburns

Another data point, somewhat extreme perhaps. I have 20 year old Ultegra derailleurs on a road bike with 3x10 gearing. Chainrings are 52/42/30 and cassette is 11-36. Using a road link, everything works really well. Chain is sized to allow 52-36 combination without damage, 42-11 still works fine with no slack, and using the 30 tooth chainring, the chain still is tensioned up through the middle of the cassette. The 30-11 combination makes the chain go slack of course, but there is no reason to ever go even close to that gear. So based on my experience, you should be fine with the right length of chain.

KCT1986

ST-7800 uses the older road (pre-11 speed) pull. It will not index properly with road 11 speed RD or other RDs that are designed to the same ratio.

maddog34

"FROM THE WEB". and it's a reputable site. take it up with them, i guess

Wanna Know the site? Search it yourself.
i'm tired of looking things up for people today.

KCT1986

From Shimano:

rccardr 

Beat me to it. 7800 and earlier will not work with 10 speed MTB stuff, either, as it also uses a different pull ratio. 9 speed is the same pull, tho.

reissue59

I run a 7400 8s with 11x32 with a woolftooth and 7400 crank with 47 and 39 rings, its great. Braze on extender on front der for the 47 ring
i run 7800 with 11x32 with wolftooth, 7800 crank 50x39 rings, its great

reissue59

34 works too, just tried it

maddog34

and that's with the 50-39 front combo, correct?
How's the Big/big derailleur tension?
did you lengthen the chain?
did you test ride the bike? sometimes road vibes/bouncing can make the upper roller hit the low gear and create problems.

DMC707 is running a 53-39 front combo.

i'd go with your 50-39, if it were my bike

DMC707

Thank you!

Sounds like i need to order a Roadlink !

What cassette did you try that was 34t? I see some of the posters stating that this gen 10 speed has a different pull ratio but i assume the cassette spacing would be the same for all 10s cassettes

DMC707

If it helps me run a more forgiving cassette i dont mind running a 50 up front at all

KCT1986

The Shimano Dura Ace shifters for 9 & 10 speed uses the Shimano standard 1.7 to 1 actuation ratio, which is fine when used with the RD of the same era (see the compatibility diagram posted above for some examples, many others also will work). This result in the correct Shimano 10 speed movement and will index correctly with any 10 speed Shimano compatible cassette. This comment does not touch on the largest sprocket or total take-up capacity.

One item to note, you didn't post what hub is on the wheel that you decided to use, and could have limitations if it is a DA freehub with the aluminum freehub body. The aluminum body needs a specific series of cassettes that are not offered in as many sizes, mostly in racing teeth range.