Cycling UK Forum

These questions are in another post but have been advised might be better to separate this question.

Some time ago I picked up a Dura Ace fc-7700 Octalink Chainset very cheaply, about £12 and never used it but did use the 39T chainring off it. Its in perfectly good condition. Now I am in the position of considering a BB change I am wondering if I should move to the Octalink seeing as the chainset I have on is an Exage weighing in at about 900g, I just weighed the Dura Ace and it is 580g which surprised me. I see the 105 5500 BB's for this are about £30. I'd be grateful if anyone can advise on the following:

1. Do you need a special specific Octalink tool to a) fit the BB (I have both types of BB tool for square taper fitting already) and b) for removing an Octalink chainset. I have read about self extracting Octalink Chainsets but as yet have been unable to find out if the 7700 is one of them.
2. Is Octalink any good as a system? Do the BB's have a good lifespan?
3. If the BB is wider or narrower than my current spindle does this simply mean after you fit that the High/Low screws on the rear mech will need a tweak, and maybe front mech too?
4. Anything else I need to be aware of?

Octalink is pretty much obsolete now having been superseded by external cupped BBs with two piece chainsets. A conventional crank tool will remove your cranks but you will need one with the little cap on to stop it wedging in the bigger bolt hole. There are two standards of Octalink the splines on the Dura Ace are shorter than on the lower end groups. Sorry I cant remember where the change over is on the BB specs

1/ You need a special tool to screw in/screw out the cups on an Octalink bottom bracket. The grooves in the cups are to an ISIS standard and they are different to the 20 groove pattern you find with Shimano square taper bottom bracket cups.

And if you have a crank extractor tool that works with square taper bottom brackets it will not work with Octalink. There are others on the market for Octalink, and others dual use ones that extract both Octalink and square taper.

2/ Octalink BB's are crap. The trade off of using a larger diameter axle were smaller bearings which do not last very long.

3/ If chainline ends up different, we are only talking a smidgen of a difference which can be sorted out by a slight adjustment of your FD. If you are replacing a road chainset with another road chainset, or an MTB chainset with another MTB chainset, you typically do not get problems.

Also note that Octalink BB's come in version 1 and version 2 flavours. From Wiki: Octalink exists in the marketplace in two variants, Octalink v1 and Octalink v2. The difference between the two can be seen by the depth of mounting grooves on the bottom bracket spindle. V1 spline grooves are 5 mm long, while V2 are 9mm long. 105, Ultegra 6500 and Dura Ace 7700 cranksets mate to version one bottom brackets, while later mountain bike designs use the deeper-grooved version two

I have an octalink BB on my specialized. It has been there for almost 10 years and is still going strong. BTW, I have removed and replaced it several times for bike cleaning etc and have used the normal shimano BB tool, the same one as I use for square taper BBs have on two or three other bikes so I think the advice that you need a different one for octalink is incorrect.

I have two Shimano Ultegra chainsets, both octalink, and they both have self extracting crank bolts, so no extractor necessary for mine.

Thanks Mechanic, yes as far as I can see from more googling the BB tool is fine that I already have. On the self extracting side maybe I will be alright seeing as the chainset I have is a Dura Ace FC-7700. Having said that maybe you have the Octalink V2, I have the V1. I have found a tool that will extract Octalink for those that are not self extracting which if I do need I will order at the time. I have gone for it anyway, a case of nothing ventured. I have ordered the 105 version of the BB compatible with mine, the 5500 for £26. Not a bad price. If I find I like it after a few weeks I will probably order a second one and store it and so defer the need to change the system over again for a while.

In the end the weight saving will be minimal, as the exage chainset I just took off is not as heavy as you would expect, 715g so my combined BB and chainset weight is about 900g, The octalink combined weight will be about 840g.

I am afraid there are issues in nearly all the comments above.

Actually to be correct there are 3 different types of Octalink bbs. The bb7700 for the fc7700 is actually a cup and cone (i.e. not cartridge) bb supplemented by needle bearings, and requires a special C-type spanner (as well as the standard splined tool) for set up and removal (unless one wouldn't mind ruining the alloy cups). The bb for the FC-m950 mtb chainset is similar, which happens to be a special case that bucks the common belief that V1/5mm spline is for road and V2/9mm spline is for mtb...

See http://techdocs.shimano.com/media/techd ... 646804.pdf

But all that is now irrelevant since the OP has ordered a simple 105 cartridge V1 bb. The potential problem I can see the OP may encounter though, is with respect to chainline. If the 109mm 105 bb has been ordered then it should deliver a 43.5mm chainline with the FC7700 per spec. However iirc, in a previous thread at viewtopic.php?f=5&t=85190, his 113mm Ti bb if identical to the JIS bb the Exage 400EX FC-A400 chainset is meant to have then the chainline should be 50mm. If so I am afraid the chance is not wonderful for a chainset with 43.5mm chainline to work flawlessly with a front mech set up for a 50mm chainset, let alone other issues that may arise such as heel clearance if not outright clash.

While a 118mm V1 exists for the triple chainset, it is not just c4.5mm longer each side afaik.

What is the current chainline?

according the sheldon brown the exage A400 chainline is 43.5, same as the chainset I am moving to. Not sure I understand the problem.

Hackfall wrote:according the sheldon brown the exage A400 chainline is 43.5, same as the chainset I am moving to. Not sure I understand the problem.

My comment is based on the information in the following Shimano technical document, which suggests a 50mm chainline.

https://dl.dropboxusercontent.com/u/535 ... 0Chart.pdf

If it is 43.5mm as measured currently then you should be fine. Have you measured it?

further question I have just realised reading the tech doc.

As I understand before I install the chainset I need to remove the cap. Is this correct? If so then I have no tool for this but reading around have seen people recommend using a couple of reversed drill bits the right width to seat snugly then pass a screwdriver between them to gently turn the cap threads around. Does that sound reasonable?

I've not used Octalink, but my impression is that you just tighten the bolt up. Those 'caps' are part of the self extracting bolt that are used (so no need for a crank extractor). The cap does need to be a little tight. A pin spanner or pin pliers are the ideal tool to use, although I suppose you can improvise, at the risk of your improvisation slipping onto those nice shiny cranks

cap can be undone quite easily with pointy pliers, tried it tonight. I will take them off before installing just because the instructions say so. I did find another comment online from someone who said it worked better taking the cap and screw fully out then getting the chainset nicely seated before screwing things back in.

Hoping my BB arrives from chain reaction tomorrow and I can get this back up and running, especially as I will be at Kielder over the weekend and looking forward to a nice ride on the roads near there.

BB-5500 Bottom Bracket arrived in post today, fitted it at lunchtime and chainset, all very straight forward. Now to find an hour tomorrow to test it before a proper ride on Friday.

No need to adjust gearing as far as I can tell so far. Front mech is operated by multiple clicks for fractional movement (shifter is Veloce 1999 vintage), and as far as I can tell the alignment is slightly different to before at the front mech end, but I had so much leeway to begin with it seems ok.
External screw in washer that goes over the screw seems to act as a "block" to enable the chainset to be self extracting, result!

Thanks for the input from everyone, gonna feel good to have this back on the road after such a long time (3 days! )

Shimano have just revived the Octalink interface for their new Claris 8 speed road groupset so it'll be around for a good few years yet.

ooh interesting thats good to know. is it compatible with octalink v1 I wonder though? which is what i have.

I have done a fast hilly 10 mile lunchtime ride and a flat 54 mile ride now on the new setup and its all good, only had to adjust the Low gear screw on the front mech as the chainset in fact did come in a little nearer to the mech, we're talking no more than a 3mm change but enough that in top top gear the chain was touching the mech, and i bottom bottom gear there was quite a gap. a turn or two on the low screw and its all bob on now.