guruguhan

Hi all,

I'm trying to install my crankset onto the BB and I can't seem to get the splines to match up. I've read the Park tool instructions, but still not having any luck. I've put one of the BB splines at the 12:00 position as they say, and then my crankset at 6:00. The splines match up (in that they look like they would slip together), but they do not. I dont want to use any significant force to wedge them together (unless it is recommended to do so - but the Shimano instructions warn against this) - so I'm wondering what I'm doing wrong. Any help is appreciated. Octalink (Shimano 105 - BB-5500) BB, Ultegra triple crank (FC-6503 Octalink). Thanks

Retro Grouch 

Are you sure your crank and bottom bracket match? There are two different Octalinks. The one for XTR and road cranks has a shorter splined shoulder and skinnier splines than the one for the other mountain bike cranks.

guruguhan

I'm not positive the splines match, that's my worry - but it looks like they are so close to matching (less than a 1mm off). The ebay store had sent this 105 BB (BB-5500) with the crank (FC-6503) I bought, I had thought they would match. I just updated my post with the model #'s of the BB and crank.

guruguhan

According to some quick searches on the web, these two are compatible. Anyone know what else I could be doing wrong?

guruguhan

Well, since the info I have says that these work together, and I think I've done everything correctly, I went ahead and bolted it down. It looks like it worked out, but I'm not positive. When the cranks are properly installed, will you see any of the BB spindle (or should the cranks always fall flush with the BB)? I can see some of the spindle on both sides of the BB with the cranks installed (when viewed from the bottom).

well biked

Other than the obvious visual lining up of the splines before you push them together, I don't do anything special when installing Octalink cranks. I've only used Octalink on mountain bikes, so I can't comment on the compatibility of the cranks and bb you're talking about, but I've always found it to be very simple to get the cranks on the bottom bracket spindle with the ones I've used. Grease the splines liberally, eyeball the alignment, and push the cranks onto the spindle with your hands to get them started. They won't go on too far with just your hands pushing, but you should be able to feel that the splines are aligned properly, as there's a distinct feeling as you push them on that the splines are engaged and are sliding together. Good luck-

well biked

You'll be able to see some of the spindle, but you shouldn't see the part that has the splines on it. Other than that, as far as the bottom bracket, you just want to make sure you have a good chainline, which relates to the bottom bracket spindle length-

nitropowered

The self extracting bolt kinda gets in the way when you first tighten down the cranks. It shouldn't catch and fit in the splines immediately, but eye ball it so you get the splines to match and carefully crank down the bolt. If you feel lots of resistance, your splines are not matching so back out and try again

guruguhan

Great then! I think its all good. I cannot see the splines, only part of the spindle. I'll probably tighten the cranks a second time after riding for a few miles.

Ah, ok. I initially incorrectly assumed the splines would slip in without the bolt (and then one uses the bolt to secure it).

Thanks a lot guys!

well biked

Hmm, with the mtb Octalink stuff I've used, I am able to start the cranks onto the spindle by hand (without the crank bolt in place so I can see the splines). As I said in my earlier post, the cranks won't go on far by hand, but I've always been able to feel the splines engage when starting the cranks onto the spindle. Maybe that's one of the differences in the Octalink road stuff and mtb stuff, I don't know-

mechBgon

For anyone else coming across this thread, here's how it should look (Ultegra 6503 crank on the 5500 spindle):

guruguhan

Thanks Mech

mechBgon

DMF 

I'm a little anal about lining up the Octalinks. Using the visual method is generally good enough, but for the arm where you don't have the other one hanging down to hold the axle steady, you can get mis-alignment fairly easily.

What I do is tighten down the bolt until the splines are just making contact with the socket. Turning the arm on the the spindle slightly, you can feel when the splines seat into the socket. Once seated, just tighten on down. Torque spec is about 32 ft-lbs.

Btw, with FC-6503 (triple), you need a BB with spindle length 118.5mm. Did you check that?

guruguhan

I do have a 118.5mm, but how is the type of crank determine the spindle length? I got 118.5 because it was correct for a proper chainline on my bike (used Sheldon's method to estimate my chainline).

DMF 

Type doesn't determine it, desired chainline does.

guruguhan

That's what I thought, why did you say that for the FC-6503 you need a 118.5 spindle length? It depends on my rear cassete, rear frame spacing, seattube diameter, etc...does it not?

Though in my case, I did go with the 118.5...

masi61

Octalink road bottom brackets don't have an adjustable chainline. The 118.5 mm is designed to work with Octalink triple cranks.
I agree about the self extracting bolt making setting the crankarm on the splines tricky. Until the self-extracting bolt starts to thread onto the BB axle, you won't engage the splines. Its possible to booger this up - so once the self extracting bolt is starting to thread on, check that the 2 crankarms are lined up 180 degrees from each other. Once they are in the correct orientation the self-extracting bolt will become easier to turn as the crank arm is now registered on the (correct) splines. I have a special allen wrench set up for this procedure that gives me more "feel": I use a mechanic's "T" handle for a 3/8" drive socket, then I use my special socket that takes different size metric allen bits and fit the 8mm bit into it. While in the "T" configuration, I can apply balanced pressure on the self-extracting bolt which gives me tactile feedback that everything is going as its supposed to. When its snug, then you slide the T handle to one side and the handle becomes a mini breaker bar which allows for the final tightening. I've found that Octalink crankarms tightened with only a standard Allen wrench CAN fall off during a ride. They really need to be tightened up! Tighter than a little Allen wrench can apply. Just my opinion.

well biked

Since all of y'all are saying the splines can't be engaged until the bolt starts pushing the cranks on, I just went and checked to make sure I wasn't saying something untrue in my above posts about Octalink mtb stuff. I've got some new-in-the-box XT cranks and a new Octalink bottom bracket (all from around '03) I just checked this on, and I'm able to fairly easily push the cranks onto the spindle, by hand, a little past the point that the splines engage. This can be done without the crank bolt in place, so it's very easy to see that the splines are aligned.........So this must be a road crank thing (and maybe XTR, too, as Retro Grouch said above) about not being able to push them on far enough by hand to engage the splines-

masi61

I think its an issue with the self extracting bolts. I'd like to be able to push the crank arm onto the splined axle until it bottoms out, THEN attach the crank bolt - just like the old days of square taper. Does anybody sell a standard crankbolt and dust cover that fits Octalink?

well biked

I have no experience with Octalink road stuff, so I can only speak of the mtb stuff, but here's what I do. Without the washer that goes beneath the crank bolt (the washer would block the view of the splines), the crank bolt, and the self-extracting ring/dust cover, position the crank onto the spindle correctly (very easy, because you have a clear view of the splines). Once you've pushed the crank onto the spindle far enough to be sure the splines have engaged correctly, install the washer and crank bolt and tighten it up. Finally, put the self-extracting ring/dust cover on, using a small spanner wrench to snug it down. It doesn't need to be too tight. I've been using Octalink on mtb's for the better part of ten years, and that's the way I've always done it. To re-install cranks, you'd need to remove the extractor ring with the spanner wrench and then you can install the cranks again the same way. I'm not sure if Octalink road stuff is made differently than that or not........I like the Octalink crankbolts/extractor rings so much I'm currently using them on an ISIS crankset on a road bike, works great. The ISIS cranks I have came with a more conventional washer and crankbolt that would require a crank puller to get the cranks off-

masi61

That sounds do-able the way you described it. The thing is, now that I've had my Ultegra 6503 triple Octalink off many times for drivetrain maintenance, I really like my T-bar/mini breaker bar routine. It works great for me and I no longer have a problem with my crankarms loosening up on a ride.

DMF 

Well, yes, but that design decision has already been made for you. Standard front chainline on a road triple is 45mm; the rear drivetrain is designed assuming that spacing. The 118.5mm BB gives you 45mm.

DMF 

That's why they make torque wrenches, masi.

DMF 

Yah. A standard M15 bolt will fit. Or you could just leave off the collar.