Retrobike Forum Index

It is currently Thu Dec 08, 2016 7:13 am

* Login   * Register * Search  * FAQ



Post new topic Reply to topic  [ 9 posts ] 
Author Message
PostPosted: Sat Nov 20, 2010 7:20 pm 
Pumpy's Bear
Pumpy's Bear
User avatar

Joined: Mon Oct 10, 2005 10:03 pm
Posts: 8145
Location: Hereford
As above, any ideas on axle length required for 7400 cranks?


Top
 Profile  
 
 Post subject:
PostPosted: Sat Nov 20, 2010 7:31 pm 
Concours Judge
Concours Judge
User avatar

Joined: Wed Jul 06, 2005 3:59 pm
Posts: 8171
Location: a proper EU country
112


Top
 Profile  
 
 Post subject:
PostPosted: Sat Nov 20, 2010 7:50 pm 
Pumpy's Bear
Pumpy's Bear
User avatar

Joined: Mon Oct 10, 2005 10:03 pm
Posts: 8145
Location: Hereford
Elev12k wrote:
112


Very speedy response, many thanks.

Looks like this http://www.sjscycles.co.uk/shimano-shim ... ?src=lfgss will do the job.


Top
 Profile  
 
 Post subject:
PostPosted: Sun Nov 21, 2010 1:04 pm 
Pumpy's Bear
Pumpy's Bear
User avatar

Joined: Mon Oct 10, 2005 10:03 pm
Posts: 8145
Location: Hereford
£5 cheaper at CRC http://www.chainreactioncycles.com/Mode ... elID=17473


Top
 Profile  
 
 Post subject:
PostPosted: Sun Nov 21, 2010 2:34 pm 
Old School Grand Master
User avatar

Joined: Wed Feb 20, 2008 12:21 pm
Posts: 5785
Location: Lost in Translation
I've got a strong feeling that the 7400 bottom bracket used ISO tapers, and the UN54 will have JIS. There's contradictory information about this on the web, but generally the sources I trust lean towards ISO for the 7400 models, with 7410 being the shift to JIS.

I think the 7400 axle was also asymmetric.

EDIT - here's Andrew Muzi, writing five years ago:

"The asymmetric 1046a Nuovo Record BB assembly has an
identical spindle with the Shimano BB7400 for the first New
Dura Ace. That pattern is correct to another dozen cranks
of top quality in that era. Or an original Phil Wood #2 BB.

That was a de facto standard among professional quality
bikes for over twenty years, across nearly every major
brand. (OK, not the two big French houses but they were
always intractable on purpose)"


https://groups.google.com/group/rec.bic ... 160f0c7230


Top
 Profile  
 
 Post subject:
PostPosted: Sun Nov 21, 2010 3:30 pm 
Old School Hero
User avatar

Joined: Tue Oct 13, 2009 3:08 pm
Posts: 240
Image

Image


Top
 Profile  
 
 Post subject:
PostPosted: Sun Nov 21, 2010 6:34 pm 
Pumpy's Bear
Pumpy's Bear
User avatar

Joined: Mon Oct 10, 2005 10:03 pm
Posts: 8145
Location: Hereford
one-eyed_jim wrote:
I've got a strong feeling that the 7400 bottom bracket used ISO tapers, and the UN54 will have JIS. There's contradictory information about this on the web, but generally the sources I trust lean towards ISO for the 7400 models, with 7410 being the shift to JIS.

I think the 7400 axle was also asymmetric.

EDIT - here's Andrew Muzi, writing five years ago:

"The asymmetric 1046a Nuovo Record BB assembly has an
identical spindle with the Shimano BB7400 for the first New
Dura Ace. That pattern is correct to another dozen cranks
of top quality in that era. Or an original Phil Wood #2 BB.

That was a de facto standard among professional quality
bikes for over twenty years, across nearly every major
brand. (OK, not the two big French houses but they were
always intractable on purpose)"


https://groups.google.com/group/rec.bic ... 160f0c7230


Interesting, I just assumed that Shimano would obviously be JIS :oops:

No real issue though as I've used JIS cranks with ISO b/bs and vice versa in the past with no issues and should be even less of an issue with a sealed b/b when there isn't the need to remove the cranks to service the b/b - I think it's the regular crank removal that messes up the taper rather than the interface itself. Not ideal admittedly, but should be fine in the real world.

The asymmetry sounds more of a concern but the judicious use of a narrow spacer or two should address that - I'm assuming that the axle needs to be longer on the drive side and if that's not the case it could be a little trickier.

Compatability - you've got to love it :wink:


Top
 Profile  
 
 Post subject:
PostPosted: Sun Nov 21, 2010 6:52 pm 
Old School Grand Master
User avatar

Joined: Wed Feb 20, 2008 12:21 pm
Posts: 5785
Location: Lost in Translation
ededwards wrote:
No real issue though as I've used JIS cranks with ISO b/bs and vice versa in the past with no issues

That's true, but you might want to pick a slightly shorter axle. ISO cranks sit a good couple of millimetres further out on JIS tapers.

The asymmetry is only a couple of mm rightward bias. You can see the difference in length of the unmachined section at the base of the taper in Simplex's picture.

Just incidentally, SunTour Superbe Pro cranks also used ISO tapers, right up until the mid nineties.


Top
 Profile  
 
 Post subject:
PostPosted: Sun Nov 21, 2010 11:14 pm 
Pumpy's Bear
Pumpy's Bear
User avatar

Joined: Mon Oct 10, 2005 10:03 pm
Posts: 8145
Location: Hereford
one-eyed_jim wrote:
ededwards wrote:
No real issue though as I've used JIS cranks with ISO b/bs and vice versa in the past with no issues

That's true, but you might want to pick a slightly shorter axle. ISO cranks sit a good couple of millimetres further out on JIS tapers.

The asymmetry is only a couple of mm rightward bias. You can see the difference in length of the unmachined section at the base of the taper in Simplex's picture.

Just incidentally, SunTour Superbe Pro cranks also used ISO tapers, right up until the mid nineties.


Thanks for that, and for pointing out where the asymmetry on that axle is - I was staring at it for ages!

It sounds like the 113mm I've ordered might well be ok, especially without the drive side bias. I can't change the order now so I'll see how I get on and if clearly no good then I'll have to order another!


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 9 posts ] 

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 14 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  

About Us

Follow Retrobike

Other cool stuff

All content © 2005-2015 Retrobike unless otherwise stated.
Cookies Policy.
bikedeals - the best bike deals in one place
FatCOGS - Fat Chance Owner's Group

Powered by phpBB® Forum Software © phpBB Group