Which triple chainset?

devonhills

I have a racer mostly equipped with Sora (crank is RPM) but I need a triple (steep hills around here).

Was thinking this Tiagra Octalink http://www.chainreactioncycles.com/Models.aspx?ModelID=11832 is a good deal, but what does it mean that it is Octalink? :?

I know I also need a new 3 speed shifter on the left, but what about the BB?

Any help appreciated by a guy new to road bikes!

Cheers

Dave

Ben6899

Octalink is the alternative to square taper BB; it's a larger and stiffer spindle with 8 splines.

Courtesy Sheldon Brown...


Is your current BB a square taper? If you don't know, maybe you could post some more bike info (year, make etc) and one of the real experts will be able to offer advice.[/img]

devonhills

Not sure, but I assume it has a square taper. Picture below (I hope)



I just looked up Octalink BB on Chain reaction cycles http://www.chainreactioncycles.com/Models.aspx?ModelID=908 and got even more confused by the sizes here!

Just as I thought I was getting my head around it - can anyone tell me what I need to buy?

Thanks

Ben6899

The Sora BB I removed from my mid-90s Peugeot frame was square taper, so I'd guess yours is also.

As for getting down to the nitty gritty of the various Octalink BB sizes etc, I'm afraid you'll have to leave me here!

devonhills

Thanks for your replies.

I visited Sheldon Brown's site - very helpful. Now I think this is what I'm going to buy:

Tiagra STi Left shifter:
http://www.chainreactioncycles.com/Models.aspx?ModelID=14060

Tiagra Octolink chainset:
http://www.chainreactioncycles.com/Models.aspx?ModelID=11832

Shimano BB ES30:
http://www.chainreactioncycles.com/Models.aspx?ModelID=2337

If anyone can confirm this will work together or advise what to change, that would be great

Thanks,

Dave

dilemna

Dave,

The BB you have chosen is a V2 for MTB. It won't fit the Tiagra road chainset. You need the Shimano 105 Octalink BB triple 68x118mm. This (and DuraAce where you can get them) is the only BB that Shimano are still doing for their Octalink road chainsets AFAIK.

On the ES30 V2 BB you have chosen the spline spacing is very slightly different to the spline spacing pattern of the V1 Octalink BB which is the type you need as far as I can see. The Tiagra chainset won't go onto the ES30 BB V2.

You need a Shimano 105 Octalink bottom bracket 68x118mm English thread,

http://www.chainreactioncycles.com/Mode ... odelID=906

Several years ago I got an ES51 BB for my Ultegra chainset by mistake as I couldn't find an Ultegra BB which are now NLA. I didn't realise that Shimano did two types of Octalink fitting for Road and MTB chainsets and you can't mix and match. So it didn't fit.

In the end I got the Shimano 105 Octalink triple BB 68x118mm which fits the Ultegra Triple Octalink chainset and I think will also be the same for the Tiagra chainset. CRC should tell you this if you give them a call or drop them an email.

You might also need a new TRIPLE front mech depending on whether your current double one has enough swing to get the chain onto the smallest and biggest rings. It would also be as well to check the chain to see if it is still within tolerances ie hasn't stretched too much or is just knackered. You will be putting on a new chainset so a new chain might be a smart move.

You will also need a crank puller and a Shimano Octalink took to tighten (and remove) the Octalink BB. You may also need a BB tool to remove your current BB but can't say which as I don't know what type of fitting it is.

devonhills

Thanks dilemna, very helpful

Cheers, Dave

Chris James

I don't want to argue with dilemma but I think the Tiagra Octalink fits V2 MTB bottom bracket.

Ultegra was version 1, but I don;t think Tiagra is.

As dilemma said, just send Chain Reacttion an email and ask them.

dilemna

Best email Shimano if CRC can't tell you.

http://www.shimanoservicecentre.co.uk/contact.php