Dura Ace crank/bottom bracket compatibility

impakt said:

Hey all,
I just bought a new frame and started to build it up. Its the first time I'm building a bike from the ground up and so far this is the first road block.

I had a complete Dura Ace 9 speed group from another bike, with under 500 miles on everything and I rode the old bike till I started removing it all to build the new frame. Everything worked perfect.

I know the 9speed DA is a bit outdated, and the frame is worthy of much more(Felt F1c Frameset). I will upgrade everything but I wanted to build with what I have now first and upgrade as I go along.

Now heres the question:

The old frame looks to have italian BB threading, the new Felt has what looks to be 68mm BB with english threading. I need a new BB, the DA cranks I have are stamped with FC- 7140 and a double.

I am not 100% sure what model BB I need. And what tool(s) I need to remove the old crank and move everything over to the new bike..

I have been riding for many years, but only bought bikes complete in the past, its amazing how much you learn when you build something and find things out that you never knew existed and just took for granted.

All help is appreciated!

I'll post some pictures of a project in a few🙂

7410?

You'll possibly need an 8mm ALLEN wrench, but may need a 14mm (?)/(or, is it 15mm?) "socket" if a "classic" hex headed bolt is securing the crank.

You'll probably need a crank extractor if you don't already have one unless you/someone upgraded to self-extracting crank bolts.

You'll probably want a 113mm, square-taper BB whose cups have ENGLISH threads ... Shimano UN-51, or better (e.g., UN-71, UN-91), but maybe a BB with a 109mm-or-115mm spindle. There are MANY other brands of BBs that you can choose/use.

BTW. Both "cups" on an Italian threaded BB (36x24) are right-hand threaded. The driveside/crankside "cup" on an English BB have a left-hand thread.

You'll need a Shimano-compatible BB tool. I recommend the LIFU brand tool because it is made with better steel & less expensive ... the PARK tool (BBT-2?) is a cheaper casting & more expensive.

If you need BOTH a crank extractor + BB tool, then you should give serious consideration to one of the ~$40US (wholesale/on-sale through most mail order outlets) starter toolkits that come in a small (~8.5"x11"😉 plastic tool case -- the two PARK Tools will cost almost as much, not counting the tax & trip to the LBS. There are misc. tools of varying quality in those starter kits -- some you'll use/need, and others you won't.

alfeng said:

7410?

You'll possibly need an 8mm ALLEN wrench, but may need a 14mm (?)/(or, is it 15mm?) "socket" if a "classic" hex headed bolt is securing the crank.

You'll probably need a crank extractor if you don't already have one unless you/someone upgraded to self-extracting crank bolts.

You'll probably want a 113mm, square-taper BB whose cups have ENGLISH threads ... Shimano UN-51, or better (e.g., UN-71, UN-91), but maybe a BB with a 109mm-or-115mm spindle. There are MANY other brands of BBs that you can choose/use.

BTW. Both "cups" on an Italian threaded BB (36x24) are right-hand threaded. The driveside/crankside "cup" on an English BB have a left-hand thread.

You'll need a Shimano-compatible BB tool. I recommend the LIFU brand tool because it is made with better steel & less expensive ... the PARK tool (BBT-2?) is a cheaper casting & more expensive.

If you need BOTH a crank extractor + BB tool, then you should give serious consideration to one of the ~$40US (wholesale/on-sale through most mail order outlets) starter toolkits that come in a small (~8.5"x11"😉 plastic tool case -- the two PARK Tools will cost almost as much, not counting the tax & trip to the LBS. There are misc. tools of varying quality in those starter kits -- some you'll use/need, and others you won't.

Dura-Ace FC-7410 crankset? That is actually the "8sp" low profile crankset from the early 1990's. This particular crankset uses the BB-7410 bottom bracket which has a 103mm length square taper spindle. Longer spindles such as 109-115mm spindles may work but it will screw up the bike's Q-factor and is not recommended. The BB-7410 came in 'English' thread which fits a 68mm BB shell or the 'Italian' thread for a 70mm BB shell.

If the original poster has a "Dura-Ace 9sp group", he would have a FC-7700 crankset, not the "FC-7410" he stated. Correspondingly, BB-7700 is the part code of the D-A Octalink bottom bracket for the 9sp D-A double crankset. The BB-7700 spindle length is 109.5mm. As a sidenote, if you have a FC-7700 crankset, use the BB-6500 from the Ultegra group (compatible with FC-7700), it is more robust and will actually last longer than the higher end D-A BB.

This Park Tool instruction page might help

http://www.parktool.com/repair/readhowto.asp?id=103

Thanks for the quick response. I bought my last bike from a LBS a few years back and it came with this setup. Everything worked great but the geometry of the frame was really [censored], and I got a GREAT deal on this framset so I wanted to keep the build very low budget but rideable and gradually upgrade for $$ reasons.

Anyway I brought the bike down to a friend at my LBS and he had the BB I needed + the tools and is doing it for free. He is actually working on the bike right now..

He recommended the same thing, upgrade the crankset/bb first thing. I am going to gradually start locating and purchasing new 10speed ultegra/da as $$ is available.

Thanks for the responses.

🙂

Wow. Just got the bike back and took it for a spin. It rides GREAT even with the relic of a crankset!

The guy at the shop confirmed the group is a newer 9speed DA but the crankset and BB are OLD. And the other bike shop should have told me.

It works good though so I cant complain!

Full carbon Felt with 9sp DA for under 1k aint half bad!

If the crankset is working, why change it? You won't notice the upgrade if you go to Hollowtech II, although it may look nicer.