Miller2

Hi All,

I have a 6700 Ultegra crank 53/39. How do I know if it is a 130 or 110 bcd? I thought it would be stamped on it somewhere but it doesnt appear to be.

bigredkevbot

It should be a 110mm but measure it like this: Sheldon Brown's Bicycle Glossary Bo--Bz

Miller2

Great...thank you.

nhluhr

If it's actually the FC-6700 and 53/39 then it is definitely 130. If it's a 'compact' FC-6750 (and 34/50) then it's 110. Just curious - why do you ask? Are you replacing the rings with something else? You won't find anything that shifts better than the hollowglide ring it comes with. As for going to smaller tooth counts, you can't go any smaller than 39 with a 130bcd but you could go with a smaller big ring.

For instance, the 46/39(130) rings from Praxis Works will work on your crank but the 46/36(110) won't.

rpenmanparker 

On 6700 there is no question as to what the BCD is. As said above, if it has standard rings (53/39) it is 130mm. If compact rings (either one is smaller than 38 teeth), it is 110mm.

bigredkevbot

Product

My mistake! Looks like it's a 130.

Miller2

Its a 53/39 for sure. I did want to change the rings to perhaps a mid compact 52/36 or even a 50/34 but I guess thats a no go.

nhluhr

Shimano did 'fix' this inherent difficulty with their new 4bolt cranksets. They all have the same bolt pattern from compact to time trial. That doesn't help you I know but in case you're thinking about swapping cranks to go compact, choosing one of the new ones will save possible future headaches. And the new ones are of course compatible with both 10spd and 11spd.

dtrain

38t is the smallest that'll fit on 130mm. That's probably not worth it. Buying a lightly used 50/34 and selling yours wouldn't cost much more. Might even consider a new 6800 crankset from the UK.

Miller2

The one I have is a new take off 6700. Never been used. What do you think I can ask for it?

rms13

You can ask whatever you like. Merlin is selling for $125 with free shipping to US right now so don't expect to get more than that.

rideBjj

53/39 is pretty much always 130bcd, I do believe.

06SpiceRed

That pretty much used to be the standard, but now days a lot of companies like are going to a 110 bcd and making larger rings. Rotor and now Shimano for example are of those, Im guessing it gives the riders a better spread of gearing options. I know personally its been nice since I normally ride a 53/39 but on one of my hill climb events I switched the inner ring to a 36 which pretty much saved my ass hahaha

Miller2

is the FC 6750 different from the 6700? Also, I understand the 6800 has different spacing and doesnt shift as well?

dtrain

6750 = 50/34

6700 = 53/39

(I think)

06SpiceRed

The 6750 is the 110bcd version and the 6700 is the 130. 6800 Shifts flawlessly. A lot of people have switched over to that newer platform because of that as well as the ability to change rings whenever.

Spot on

Miller2

Good deal...thanks. To be clear, 6800 shifts flawlessly when used in conjunction with 6700 10 spd shifters and derailleurs?

06SpiceRed

Yep! to avoid any confusion, on one of my bikes I have a full 6700 groupset with the exception of the crank being a 6800. Aboslutely flawless.

On a side note, if you are using a 6700 group, I without a doubt, highly recommend going and recabling everything with the new 6800/9000 polymer cables. They make shifting the 6700s significantly better. My only regret was not doing it sooner!

Miller2

Thanks very much!!

Miller2

Not to be a nuisance with questions but I'll be replacing a Force crank on a Fuji Altamira with a BB36. The 6800 crank can be a direct swap with no need to replace the current BB?