Mavic Starfish 631 Chainset on Look KG196

[Piez]

Hi, I'm looking for a little advise.....I'm trying to fit a Mavic Starfish 631 Chainset to my classic Look KG196 but have a problem, the current Shimano 7400 BB isn't compatible. So could people please tell me what BB I need for this combo (brand, length etc) and if the Look frame with be English or Italian threaded.

Many thanks

 

[John J]

The frame could be either English or Italian. You need a 114mm ISO bb for a Mavic 631 double, 119mm for a treble.

Edit. Having just checked the Mavic docs 114 to 116mm for a double, 119 to 123 for a treble.

A Campagnolo 115.5mm can be a good compromise for the double: not many ISO's are around in 114, 115, 116mm length.

The Mavic docs are in the archive on this site I think.

 

[Piez]

Re:

Many thanks for the info. Any idea how I check the thread type on the look?

 

[John J]

Yes. Your existing 7400 will be marked, either 36x24 if it's Italian or 1.370 x 24 if it's English.

 

[one-eyed_jim]

The KG196 is BSC threaded:

http://vive-le-velo.blogspot.co.uk/2012 ... lagen.html

I'd be surprised if your current 7400 BB didn't work acceptably with the MAVIC cranks. Dura-Ace cranks used ISO tapers prior to the 7410 model, and the spindle length (112mm) is close to what you need. I'd recommend trying the BB you have before sourcing a replacement.

 

[Midlife]

Shimano used an ISO taper but started off narrower than others so you might find the small chainring touching the chainstay but certainly worth a go

Shaun

 

[Piez]

Re:

Shaun got it in one, the chainring hits the frame, plus the square taper on the drive side seems to not fit properly, the BB taper angle appears great than on the crank.

 

[John J]

The KG196 is BSC threaded:

http://vive-le-velo.blogspot.co.uk/2012 ... lagen.html

I'd be surprised if your current 7400 BB didn't work acceptably with the MAVIC cranks. Dura-Ace cranks used ISO tapers prior to the 7410 model, and the spindle length (112mm) is close to what you need. I'd recommend trying the BB you have before sourcing a replacement.

I've heard the earlier dura ace square tapers being referred to as "JIS low profile", but they are not the same as ISO.
I'd forgotten that LOOK had standardised on English BB threads by this time, thanks for clarifying that.
J

 

[one-eyed_jim]

I've heard the earlier dura ace square tapers being referred to as "JIS low profile", but they are not the same as ISO.

I hadn't heard the term "JIS low profile" before, so I've done a little research.

The phrase seems to originate with the Phil Wood company, and first appears on the internet in 2004 on Sheldon Brown's "Harris Cyclery" commercial website referring to certain short Phil Wood axles:

http://tinyurl.com/pnqqcmv

In Dura-Ace terms, the only cranks using such short axles were the 7410 series: the last square taper Dura-Ace cranks before the introduction of Octalink splined pipe-billet axles.

I've used the 103mm BB-7410 unit, and hadn't noticed that its tapers differed in form from other short Shimano JIS axles. I have a couple tucked away somewhere, and when I get a chance I'll dig them out and measure.

You can follow the evolution of the phrase "JIS low profile" here:

http://tinyurl.com/zgty9az

and here:

http://tinyurl.com/jp9pekl

The various mentions of "JIS low profile" on velobase seem to be conjecture based on a misunderstanding of the Phil Wood description of low-profile (i.e. 7410 series) Dura-Ace cranks as "older".

 

[one-eyed_jim]

Re: Re:

the chainring hits the frame, plus the square taper on the drive side seems to not fit properly, the BB taper angle appears great than on the crank.

When you say "the square taper on the drive side seems to not fit properly", do you mean that there's a difference in fit between the left and right cranks? If your cranks aren't new, it's not impossible that one or both of the tapers has been enlarged through prior use with an incorrect axle. New 631 cranks are a good fit on an ISO taper, in my experience.

I'm not very familiar with the KG196, but is there anything about the frame that would prevent you using a threadless MAVIC unit? They're not cheap, but they do turn up fairly frequently on eBay.