francophile 

Full disclosure, I may be hopeless w/sealed cartridge setups. The Shimano LP units were just gaining steam around the time I left my last wrenching job as a late teen, never to return.

I picked up this Cdale for some retro fun. Ultimately planning for 1x10 / 1x11, probably with an interim 2x9 / 2x10 setup while I acquire parts. OEM setup was a triple (3x7) w/Altus (FC-CT02) and BB-LP26 (68x118).

I'm installing an Octalink V2 chainset (FC-M752). Shimano says compatible BB are Octalink V2 models BB- ES50, ES51, ES70, ES71. Only ES51 is widely available, but 2x more $$ than the most-recent V2 Octalink (BB-ES300).

My questions, if anyone can help:

1. Any reason I couldn't technically use the BB-ES300 in this case? Any pros/cons with tech/longevity/etc on the newer model? Is there a centerline diff'ce with the various Octalink BB?
2. Any technical / fitment issues I should be worried about moving from LP square taper sealed @ 68x118 to Octalink v2 sealed @ 68x113 or 68x118?
3. I planned to buy both a 113mm (for 1x) and 118mm (for 2x). I installed an ES70 68x113 last night, at a glance the, the 113 chainline looks good for a double setup. Should I bother with the 118 at all? (M752 does support a triple)
4. Any other advice, gotchas, or "aha!" you can share with a newbie to Octalink? I'm seeing mixed and limited info here and at MTBR, and an hour's searching couldn't answer the above adequately.

Appreciate any input.

Iride01 

1) As long as your cranks are octalink v2 and the shell is BSA or 1.37" x 24 TPI and the width is correct for your shell, then go for it. However if you have a E-type DR then you might need a BB-ES300-E. Not certain I quite understand the difference though.

2) I don't know, I skipped cartridge bb's altogether when I chose to run away from the madness of square taper spindles with cup and cones, Along with all the things you have to consider when changing cranks. I found modern two piece cranks much saner with respect to figuring out what works. By design, they eliminate all the superfluous info that has to be known to swap square taper cranks and BB's. (IMO)

3) If it looks good it looks good. Will 2.5 mm make it look better? If you change cranks to a triple, then that may or will change your chain line. So how's that for a non-answer?

4) I'd do Octalink, Isis or anything other than square taper (IMO). What about 2 piece cranks in the MTB world? How do they fair for durability? For road bikes their they are the ideal thing. Again IMO.

francophile 

First off, really appreciate the candor and honest response. Refreshing.

On this one point:

I'd honestly prefer going with 2pc, but after a couple weeks of casual search and the last 3 days heavy search, finding anything used in 2pc MTB crank/shell bits, in good condition, silver & black ideal, for under $150 is difficult and under $100 has virtually impossible. I got this bike for about half that. I'm hoping to go budget but flexible and re-use where possible.

Seems everyone in the MTB world - a world I have no friends and few acquaintances in - must hold/donate all their "old" stuff, with some dropping it on eBay for outlandish prices? Everyone I know in MTB has gone full 29'er at this point and tossed all their 26er stuff. No good used parts outlets I can find. The local co-op I donate buckets of parts to and occasionally work on racking initiatives with was mostly picked over this Sunday, I ended up with some 26x14 BMX wheels to rebuild for a friend, but came up empty for myself....

For the record, I typically don't ride MTB, 70s-80s vintage road/touring is my cozy place, although I've come to appreciate some more-modern tech like brifters. I only dove into the MTB world during the pandemic thanks to a good source I found for used '90s/'00s bikes at good, rebuild-worthy pricing. I also have a kickass trail that recently opened up a couple blocks from me that's gravel/pack, but just enough rocky areas that my light cycloxross bike isn't ideal.

Edit: Just saw the reference to mechs/E above. Current mechs I've allocated for this project are RD-M591 long cage and FD-M590. Both are new. Don't love the design, but I think they'll blend in on the build. I don't think I'd need to go the E-route. I read up on that last night, didn't bother to remember what it was about, instead logged a mental note "yep, no need to worry about that!"

CliffordK

If you do choose to purchase a bottom bracket on E-Bay (or even some online vendors), there is often confusion between V1, V2, and ISIS.



All V1 should be compatible (other than length, of course).
All V2 should be compatible (other than length, of course), but it is NOT compatible with V1.
ISIS is different, and independent from the Shimano designs.

Iride01 

Being that the BB shell is 1.37" x 24 TPI there is a lot of options out there for you. Just pay attention to the BB shell width and make certain the BB will fit that width and the cranks give you the correct chainline.

I'd think you'd come across something soon. What about that co-op you donate parts to? Still, I think you should be able to find cranks, rings and BB for under 100 USD new if you aren't too picky. And if you have the original, then put it back in when you get rid of the bike and keep the crank for another project.

I agree with your assessment of ebay and such for used. The sellers want retail new for used old stuff. Vintage is even higher. But sometimes someone puts something up that is reasonable.

3alarmer 

.
...IIRC, the 113 Octalink unit is the double ring length. the 118 is for the triple ring setup, with a small ring installed.

I've built out two of them in the past six months, on standard 68mm BB frames with standard threading, and there were no issues with installation or fitting to the proper crank. They do run pretty close to the frame, so you shouldn't have any trouble pulling off the second ring and going with a 1x setup, if that's what you decide to do, if you use a 113 unit.

francophile 

Definitely, that's how I finally found this Deore XT chainset I'm bolting up now for $65. Scored it as local pickup, seller tossed in an extra Shimano 36T ring to boot after hearing I may be seeking some variety. I saw a few new 2pc $70-80 options out there - but it was arms only, no rings, no hardware, nothing extra, and rings start in the $25-35 range new on sale.

Real sticker shock was looking at prices to go straight-up 1x11 or 1x12 new. Adding everything needed into my cart just for the levers, mechs, crank, freewheel, BB all on clearance or sale across a couple sites, I was looking at over $600 with tax and shipping ... 10x what the whole bike cost. Even the Chinese Shimano knockoff packages on fleabay and Amzn are $250+ without a crankset and BB.

Anyway, I think overall y'all helped me to figure out my direction. I think I'll buy one of the ES51 / 68x113 units for $40 because I'm seeing comments online that it and the ES71 are lighter with more longevity than ES300, then pick up a space ES300 / 68x118 in case I ever decide to go back to a 3x setup later.

Last thing I'll say although I've already said too much is this: I was pretty surprised, the MTB subforum's marketplace and main BF marketplace rarely have any '90s/'00s parts listed. I know riders are out there. Maybe MTB being more full of abuse and rough operation leaves parts mangled? Like the number of licks it takes to get to the center of a Tootsie Roll Tootsie Pop, the world may never know....

(where's my beer?)

francophile 

You're correct, 113 is 2x length. I got confused for a minute last night wondering why there wasn't a 109mm for 1x, but realized that would nearly or completely put the crankarm into the chainstay, or rubbing the BB shell.

But the current 113 BB I used to test chainline is 73x113, and my shell is 68, so I could only secure one side or the other and I'm stuck buying a replacement, and a more-stout 8-prong cup installer. Created the thread to make sure I'm not missing anything before parting with the coin to purchase.

sweeks

This ^^.
I have a 20-year-old Airborne with 3 x 9 Ultegra. The crankset is Octalink V1. A couple years ago I learned about the change from V1 to V2.
Since I like the appearance of my crankset, I figured I should get a spare BB. The V1 was hard to source, but I found one. Whew!

The appearance of this crankset pleases me. :-)