ex4cylnotch

I just purchased a compact double crankset that requires an octalink bottom bracket. right now i have a mega-exo bottom bracket. Is it a bad idea to change to the octalink? what are the pros and cons of changing to the octalink?

thanks

triplebutted

Doesn't the mega-exo have an integrated BB spindle?

Steev

The pro of going to an Octalink BB is that your crankset will be able to fit on it.

wrk101

I never liked how the crankset attached to the Octalink. It didn't seem as secure as the old square taper style. Seems over-engineered to me.

Just a personal opinion of course.

onbike 1939

It may be, but it's one you share with many.

z415

Yes. It's an outboard bb.

z415

Pro: swapping bbs will be cheaper than swapping cranks for most price points.

AnthonyG

Octalink was a fine system and I don't see any great advantages in going to megaexo other than it helped manufactures sell new stuff. You won't loose any functionality in going to Octalink. The only disadvantage I can think of is that you will need a matching BB and when you do this take note that there is an octalink version 1 and a version 2 and from memory they are compatible one way but not the other. Make sure you know what you need before buying an octalink BB.

Anthony

z415

I was under the impression that v1 was "road" and v2 was "mtb" or vice-versa.

Sheldon Brown has a good write-up on this, but I am too lazy too look it up. I believe the real differences concern the depth of the splines.

Dan Burkhart 

It's the length of the slpines that's different. The V1 for road and V2 for MTB is only a general rule, not absolute. I have run into some road cranks, Tiagra I think, that use the long slpines.
Dan

AnthonyG

Thats it. Different spline length. From memory you can use a long splined BB with a short splined crank but NOT the other way around.

Anthony

z415

Ok, I just checked Sheldon Brown, it is definitely the spline depth/length that is different and IT IS NOT road v. mtb.

It is more high end v. low end: DA, Ultegra, 105 and XTR use(d) v1 (short) and Deore, XT, LX, Sora, and Tiagra for v2 (long).

He did not mention of any cross-compatibilities.

ex4cylnotch

thanks for all the replies, just wanted to make sure i wasnt swapping to something they may not be as good as what i have, from what i have read the octalink stuff is good, i think i will go ahead and swap.

again thanks.

Steev

What no-one has come out and said out-right is that if you want to use the crankset, you've got to use a BB with the matching interface, it simply won't fit on anything else. Also, as mentioned above, there are two versions of Octalink spline, know which you have before ordering a BB.

BearSquirrel

It's WAY more secure than the old square taper. I've never had an Octalink arm fall off from working it's way down the taper. I've trashed three square taper cranks this way.

I hate, hate, hate, square taper!!!!!

On the bad side, people have reported that the smaller bearing size tends to lead to premature bottom bracket failure. But at 280#, I never had to replace an Octalink bottom bracket for cross country use.

JanMM

You seem to have anger issues......maybe you should talk to a crank counselor.

well biked

This is true, but in the case of Octalink it's merely theory, not reality. It's very difficult to wear out an Octalink bottom bracket. I mean seriously diffificult, they're as bombproof as you'll find.

Some ISIS bottom brackets, particularly the early ones, were an entirely different story.

rmfnla

Lots of opinions, very few facts. I wonder how many posters here have actually worked with both systems..?

I have, and I have issues with the Mega Exo design. The off side (non-drive) bearing does not seat against the bottom bracket shell, it tightens up against an alloy sleeve that you slide into the shell of the drive side bearing assembly.

There is a rubber O-ring that goes under the off-side bearing to fill up some of the space, but the bearing never tightens against the frame, just this sleeve.

FSA did this to ensure that there would always be the correct spacing betwen the bearings regardless of BB shell variations but the result is the off-side bearing loosens up easily and requires constant attention.

FWIW, I have Octalink on several of my bikes and have yet to have a problem with any of them.

triplebutted

I stripped an Octalink once. But the strip was in the left crank, not the spindle. The spindle is quite strong. I just replaced it with cheapo Ritchey crank and its been going well ever since.

HillRider

I've had very good service from two different Octalink bottom brackets used with Ultegra cranks. They have been durable and long lasting and both are still in service after thousands of miles.

The splined bottom bracket design, which includes both Octalink and ISIS, got a bad name from some of the cheap and/or poorly made ISIS bb's which failed early and often. Octalink does not have that weakness.

That said, Octalink is now obsolete and Shimano's only current sealed V-1 bottom bracket is the 105 level BB-5500 which is available in both double (109.5 mm) and triple (118.5 mm) widths. The Dura Ace (BB-7700) double Octalink is still listed by Licktons but it is not a sealed unit and requires routine maintainence.

ex4cylnotch

All ,
again thanks for all the info, i appreciate it.

Hillrider, How often do the non sealed units require mainatenance? thanks

HillRider

That depends heavily on your riding conditions. If you ride in dry, clean conditions, probably annually is enough. If you ride in rain, snow, sand, etc., etc., a lot more often.

Frankly, the Dura Ace's only benefit is its lighter weight. Unless you are an extreme weight weenie, get the BB-5500 or try to find an NOS Ultegra level BB-6500.

ex4cylnotch

awesome, thanks for all you help and information !!

daveornee

I got 30K + miles out of a BB7700 serviced once a year.
I replaced it with BB-6500 and never needed service in another 15k + miles and went with the bicycle when it was sold... everything else on the bicycle was Dura Ace.
We use the XTR Octalink BBs on our tandem. They replace XT level square BBs. We certainly prefer Octalink to out previous XT square BBs. Tandem now has over 100K miles.
I looked at the Mega-Exo and was not impressed with the design or implementation.
If you get the correct Octalink BB and mating Octalink crank set, I think you will be good for many years and many 10's of thousands of miles (or kms).

z415

I think Octalink feels better than square, but I've not gotten to the point where I can compare longevity or whatever.