Trenton

Will someone please tell me what else I would need to buy to switch my Dura-Ace 7800 53/39 crankset with an FSA SLK Carbon compact crank? I have a 2006 Fuji aluminium road frame with the DA 7800 bottom bracket. Can I just pull the DA 7800 crank and use the FSA crank with the DA 7800 BB? Are there specific Bottom Bracket cups that match the FSA SLK crank?

I would like to use this FSA Carbon Crankset:


On my 2006 Fuji Roubaix SL w/Dura-Ace 7800:

I have a short-cage DA 7800 rear derailleur and DA 7900 10speed 11-28 cassettes.

Thank you!!!

Trent

mprince

I don't believe the Shimano BB cups will work with the FSA crankset, you will need a new BB.

Disclaimer - the most modern BB I am working with is Shimano Octalink, so I am a bit dated in this area.

Trenton

That's funny - when I first used the Fuji frame, I used Ultegra 6500 and liked the Octalink crankset.

Trenton

Correction... I used Ultegra 6500 on a Giant Kronos frame. Then switched that to DA 7800 and then moved that over to the Fuji Roubaix SL frame.

noodle soup

You will need a different BB for that crankset because of the 30mm spindle. If the frame is BSA threaded, something like this will work.

https://www.jensonusa.com/Hope-6873m...Bottom-Bracket

Camilo

Cranks usually specify what BB to use with them. Does the bike have a threaded or press-fit BB? Either should be doable, just that the threaded might be easier for a DIY'er. There's press-fit adapters for almost everything. FSA's a common crank, so that should not be a problem.

Drew Eckhardt 

Scratch that, the BB-right mark hides in the glare.

Kimmo

Onya Drew.

I've seen those FSA cranks before, but I only just noticed how hard the rings mimic 7800.

...Hang on - BBRight cranks? Isn't that just BB386 evo?

noodle soup

It's a 30mm spindle, so Drew's advice is incorrect.

noodle soup

"What is the difference between BBright™ and BB30™? A. For the crank, BBright™ uses the same diameter axle as BB30™, with the addition of 11mm length on the left side of the spindle, and the left crank is straighter, (similar to existing arms for external bearing cranks)."

these might work on the OP bike, but he'll need a BB like this one https://www.jensonusa.com/Hope-6873m...Bottom-Bracket

Drew Eckhardt 

Yeah, that "BBRight" mark is hiding in the flash glare.

Without that the SLK Light cranks are 24mm parts.

Trenton

Thank you everyone for your quick answers! I've read the advise and it doesn't sound as easy as a switch as I had hoped, or assumed. So I am going to stick with the 7800 53/39 crank-set for the summer and next winter beg my boss (wife) for a new carbon bike.

My next question would have been whether the 7800 DA short-cage derailleur would work with the compact crank-set I asked about. And if not, then there would be another purchase.

noodle soup

It's really not a big dual to swap the BB, but I'd rather have the 7800 crankset.

Are you trying to get a smaller inner ring?

The derailleur will work fine with a compact crank, but a 28t max is the largest cassette you can use.

Trenton

That's exactly what I'm trying to do... get a smaller, inner ring for the hills around the Susquehanna River in south, central Penna. Do you know of anyone that makes rings for DA 7800 cranks? I switched the cassettes to DA 7900, 11-28t.

noodle soup

you can get a 50T big ring, but the smallest Shimano inner ring is 39t.

look around for a 38t inner, but that's not much help.

RiceAWay

Firstly you need to make certain that the bottom bracket is large enough in diameter to sustain the 30 mm MegaExo crank axle. Many are not.

Also be careful NOT to get a BB50 cranks since there are a ton of those out there for real cheap. These only work on narrow carbon fiber BB's with push-in bearings.

If you have a BB386 crank and frame BB you just buy the correct BSA BB386 30 mm cups and screw them in. Do NOT overtighten since BSA cups normally tighten themselves and if they are tight to begin with they can lock in and be extremely difficult to extract in the future.

mercator

I have the same crank and derailleur as yours and successfully run an Ultegra 12-30 cassette.
Ratios are comparable to a compact with an 11-28 cassette.
I had to adjust the B-screw to the maximum position.

noodle soup

most mechanics know that Shimano is a little conservative with the max cassette cog rating. 30t isn’t surprising for a 7800 derailleur, and using a 50/34 crankset isn’t a problem for that derailleur either.

the problem he has is that his crankset won’t take a 36t or smaller chainring.

if I was the OP, I’d look for a silver 5700 compact crankset, and a 12-30 10spd cassette.

noodle soup

if that crankset is in good shape, and the rings are low mileage(under20k miles), selling the crankset should pay for the parts.

Trenton

Wow, again thank you everyone for the continued comments - you guys really do care!

I think I'll try the Ultegra 6700 12-30t cassettes! I didn't realize they existed and I understand your reference to the B-screw adjustment to pull the pulley/cage away from the 30t sprocket.

I think I'll try the 12-30t this summer and stick with the DA 7800 crank.

Trent

Trenton

So... just to add an ending to this story for now, I'm going to try a mid-compact DA 9000 crank (riding 40+ miles this afternoon in Lancaster/York counties). First impressions from the stand is the new 9000 crank-set is noisier than the DA-7800. Of course, not an issue on the road. The other thing I did (wrong/incorrectly) was shorten the chain, so I'm a bit nervous. With the 52/36 crank, and pedaling in the 36 up front and 28 in the back, I could hear additional noise in the back - not that the rear derailleur was bouncing off the 28T, just noticeably noisier, kind of a grinding sound. I pushed the hanger adj, B-screw all the way in to push the derailleur off the 28T to no avail... so I cut out a link of the chain. That worked BUT if I use 52 & 28, the rear derailleur is basically a straight line and once stuck the crank, ergh!

Not sure what's next... OTHER than never using 52/28 or even 52/26 combos.

I'm thinking about replacing the rear DA-7800 with a DA-9000 rear derailleur - thinking, well hoping DA-9000 has a longer cage. Does anyone know if that's the case? The DA-9100 rear cage certainly looks longer but it's mounting bolt area seems different than the mount for my DA-7800 derailleur.

Anyway, thank you everyone for helping me. Trent.

mercator

A couple of comments:
- cross-chaining (52/28) is usually a bad idea. You should shift to the small ring before you get to the smallest cog. The chain needs to be long enough to handle it, but that doesn't mean you should ride that way.
- I don't think shimano recommends mixing 10 and 11 speed shifty bits, or if it can even be made to work. You are probably ok with the 11 speed crank, but if you go to a 9100 derailleur, you will likely also need 11 speed shifters, cassette and chain.

noodle soup

Those components should work fine together, with proper adjustment, and chain length.

Time to watch some Park Tool videos, or pay a professional to set it up.

Trenton

...new 11s shifters, cassette, chain and a second mortgage. Kidding, the parts are not all that expensive and a fun project next winter.

Thank you for your comments.

noodle soup

Just get a new Di2 bike. Problem solved.

In all seriousness, just pay a shop to set up the components you have, and replace the chain if needed. There's no reason why those components you own shouldn't work perfectly together.