Swaping Ultegra 6800 crankset with Dura Ace 9000?

[StanK]

This should be an easy question for more than few folks here, I'm sure. I was trying to find answer with "almighty" Google, but without success.

So, title says everything. Why I would change it, what's wrong with Ultegra crankset?
To be honest - nothing. But 9000 Dura Ace is, for me of course, best looking crankset still around, and that alone would be good reason to go for it.
Of course, too expensive to change it just for the look, so other thing that I would like to change is crank lenght. Now it is 172,5, and few calculators said that for me would be better 167,5 to 170. And last but not least, that would be cca. 60g less on my bike

So, is it simple to change from one crankset to another, or is it ... not that simple? Right now BB is "Shimano SM-BB71". I found that on the net. I suppose that BB must go.
And, what ... I just buy BB for 9000 crankset and that's all? Would it fit to the frame without any problems? Any other possible problems?

[spdntrxi]

you dont need to swap BB... they are both 24mm... just slide the 9000 in and call it done. Unless your rings are different then you might need to adjust derailliers.

[73Bronco]

What he said, easy peasy.

Sent from my SM-G960U using Tapatalk

[StanK]

Wow, that's great news. Thanks.
Now it is 50/34 and it would stay that way. I use 50-11 for maybe 47 seconds in a month (no long steep descent around), so no need for bigger rings.

[mattr]

I just did 6800 => 9100 this afternoon (and popped the 6800 onto another bike.)
Worst/longest job was trying to pop that little pinned tab out of the left hand crank arm without removing the bolts.
Rest of it was just plug and play, technically less than a 10 minute job to do both.

[StanK]

There you go, always some unexpected things pop up. I wouldn't do it myself anyway

Now all I have to do is track down some used, but almost new (and no more than $300 ) 50/34 with 170 or 167,5 cranks (very rare, especially SH). I'm not in a hurry, so plenty of time to wait on right offer.
I didn't decide yet which to take. I read all that pro et contra (long vs. short) and ... I guess I will go on hunch, but I would probably buy 170 as "safe option".

[adilosnave]

Someone please correct me if I'm wrong, but changing from Ultegra 6800 to DA 9100 or Ultegra 8000 won't work perfectly as the chainline won't be correct. Don't recall specifics but I believe the inner chainring has been moved in-board slightly in order to help with some gearing ratios.

[kdawg]

You’re right - the inner ring is 0.4mm more inboard and the outer one isn’t in the same position. Supposed to make less chain rub in certain combinations.

In most circumstances that won’t make much difference but on some frames it can mean the front shifting wouldn’t be right and you’d need to upgrade the front derailleur too.

I’ve seen a lot of bikes with the upgraded chain set though without any problems. 0.4mm doesn’t seem a lot!

[StanK]

... changing from Ultegra 6800 to DA 9100 or Ultegra 8000 won't work perfectly as the chainline won't be correct..

But with DA 9000 wouldn't be a problem?

[adilosnave]

That's correct. Going from 6800 to 9000 isn't a problem. When things are super precise, 0.4mm DOES matter.

[bikebreak]

The 167.5 DA is very nice to try if you usually use 170

[mattr]

i'll not find out if 0,4mm matters for a few weeks. No ones riding D-A outside for another couple of months. All worked perfectly in the stand.

[StanK]

... No ones riding D-A outside for another couple of months...

Why? I would ride, can't see why not. A Year from now, in this time of year, I hope so.
Although, I do not ride if roads are wet. Summer or winter, no difference.

[mattr]

No one *here* is going to be riding D-A outside for a couple of months.

[adilosnave]

No ones riding D-A outside for another couple of months.

Why would nobody use Dura-Ace outside? Maybe I'm missing something. Stuff is bombproof.