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-   -   Taper of a Mavic Bottom Bracket (http://forums.thepaceline.net/showthread.php?t=101318)

Kontact 01-15-2012 01:33 AM

Quote:

Originally Posted by oldpotatoe
Sorry, but it's still JIS taper.

Yesterday I collected a 1970s Nuovo Record spindle, a 1980s Athena Spindle, the last Chorus square taper, a Shimano UN-54 and a Mavic cartridge unit for the Starfish crank. I used calipers to measure dimensions and held the spindles taper to taper to observe if they remained parallel.

All the Campy and Mavic spindles were the same taper. The Shimano was a different, shallower taper.

Shocking conclusions:
The Mavic is ISO, just like 3 decades of Campy.

ISO and JIS are not the same taper angle. If ISO is 2 degrees, the Shimano JIS is like 1.7 degrees. This was shown by both where particular caliper settings landed on the taper, but also how a JIS spindle will lean toward the centerline if placed taper to taper against an ISO.


I'm buying an Italian threaded 115.5 Campy BB that will work great with both my Starfish and old Athena crank, unless the Starfish is screwed up from the UN-72 it was mounted on.

oldpotatoe 01-15-2012 07:30 AM

Quote:

Originally Posted by Kontact
Yesterday I collected a 1970s Nuovo Record spindle, a 1980s Athena Spindle, the last Chorus square taper, a Shimano UN-54 and a Mavic cartridge unit for the Starfish crank. I used calipers to measure dimensions and held the spindles taper to taper to observe if they remained parallel.

All the Campy and Mavic spindles were the same taper. The Shimano was a different, shallower taper.

Shocking conclusions:
The Mavic is ISO, just like 3 decades of Campy.

ISO and JIS are not the same taper angle. If ISO is 2 degrees, the Shimano JIS is like 1.7 degrees. This was shown by both where particular caliper settings landed on the taper, but also how a JIS spindle will lean toward the centerline if placed taper to taper against an ISO.


I'm buying an Italian threaded 115.5 Campy BB that will work great with both my Starfish and old Athena crank, unless the Starfish is screwed up from the UN-72 it was mounted on.

All are 2 degrees, the differences are actual dimensions in millimeters of the taper, essentially how long they are and where measured.

Reference Sutherlands................

Also from Sheldon Brown(may he rest in Peace)

"Square Taper
Traditional cotterless cranksets use a tapered square spindle (axle) end. The sides of the end taper at a 2 degree angle compared to the centerline, 4 degrees compared to each other.
While there is general agreement about the angle, there is no such agreement about the actual width cut off. There are two main standards in current use:


ISO
ISO square taper spindles run longer, and taper down to a smaller end than J.I.S. spindles do. Most European-made square taper cranks and bottom brackets use the ISO dimensions.
ISO models include:

Campagnolo
Older Stronglight
Nervar
TA
Japanese N.J.S. track parts, such as Sugino 75
(Note: Old Ofmega/Avocet spindles were quite a bit skinnier/longer even than ISO. There are no modern bottom brackets that work with old Ofmega/Avocet cranks.)

J.I.S.
J.I.S. is the Japanese Industrial Standard, and is generally used on square taper cranks made in Asia.
J.I.S. spindles are shorter and blunter, they don't taper down to quite as small a square. J.I.S. models include:

Ritchey
S.R. Sakae Ringyo
Shimano
Specialized
Sugino (except N.J.S. track models and some older units.)

Kontact 01-15-2012 12:36 PM

Quote:

Originally Posted by oldpotatoe
All are 2 degrees, the differences are actual dimensions in millimeters of the taper, essentially how long they are and where measured.

Reference Sutherlands................

Also from Sheldon Brown(may he rest in Peace)

"Square Taper
Traditional cotterless cranksets use a tapered square spindle (axle) end. The sides of the end taper at a 2 degree angle compared to the centerline, 4 degrees compared to each other.
While there is general agreement about the angle, there is no such agreement about the actual width cut off. There are two main standards in current use:


ISO
ISO square taper spindles run longer, and taper down to a smaller end than J.I.S. spindles do. Most European-made square taper cranks and bottom brackets use the ISO dimensions.
ISO models include:

Campagnolo
Older Stronglight
Nervar
TA
Japanese N.J.S. track parts, such as Sugino 75
(Note: Old Ofmega/Avocet spindles were quite a bit skinnier/longer even than ISO. There are no modern bottom brackets that work with old Ofmega/Avocet cranks.)

J.I.S.
J.I.S. is the Japanese Industrial Standard, and is generally used on square taper cranks made in Asia.
J.I.S. spindles are shorter and blunter, they don't taper down to quite as small a square. J.I.S. models include:

Ritchey
S.R. Sakae Ringyo
Shimano
Specialized
Sugino (except N.J.S. track models and some older units.)

Yup, I've read all the same references, like where Sheldon says that Superbe Pro is a Campy taper.

But instead of repeating all this second hand stuff that may or may not be correct, I measured them. ISO and JIS are both different dimensions overall, and taper at slightly different angles. I didn't expect that to be the case, and confirmed my measurements two different ways.


Every time I read the many threads on various forums about Mavic spindles, no one seems to actually have one to measure. But I have all of them at my disposal. If you have the same items in front of you, I would suggest measuring them yourself.

Sutherlands and Sheldon Brown are wonderful resources, but neither one is a Mavic factory rep, and we don't know where they got their information. That is why he says "there is general agreement...", because none of this is first hand.

I got my information with my eyes, and I can't imagine not believing them because Sheldon Brown wrote something different that was in "general agreement".

Kontact 01-15-2012 12:52 PM

And just to add to the confusion, here's some other interesting stuff:

http://velospace.org/forums/discussi...ottom-bracket/

http://www.bikeforums.net/archive/in.../t-533332.html

All about how older Campy is also neither ISO or JIS, but different than what I observed.

oldpotatoe 01-15-2012 01:24 PM

Quote:

Originally Posted by Kontact
Yup, I've read all the same references, like where Sheldon says that Superbe Pro is a Campy taper.

But instead of repeating all this second hand stuff that may or may not be correct, I measured them. ISO and JIS are both different dimensions overall, and taper at slightly different angles. I didn't expect that to be the case, and confirmed my measurements two different ways.


Every time I read the many threads on various forums about Mavic spindles, no one seems to actually have one to measure. But I have all of them at my disposal. If you have the same items in front of you, I would suggest measuring them yourself.

Sutherlands and Sheldon Brown are wonderful resources, but neither one is a Mavic factory rep, and we don't know where they got their information. That is why he says "there is general agreement...", because none of this is first hand.

I got my information with my eyes, and I can't imagine not believing them because Sheldon Brown wrote something different that was in "general agreement".


Whatever...2 degrees is 2 degrees, not 1.7 degrees and Mavic is JIS, from my experience with them in the early 90s when I installed a bunch of them on Zap/Mektronic and the last click shifting Mavic group.

"But instead of repeating all this second hand stuff that may or may not be correct"

How is Sutherlands, Sheldon and Phil Wood 'second hand'?

But 'spec' that Mavic crank you are trying to install. Unless it's new, the flats have been deformed anyway, regardless of JIS, ISO or WGS taper.

Kontact 01-15-2012 02:16 PM

Quote:

Originally Posted by oldpotatoe
Whatever...2 degrees is 2 degrees, not 1.7 degrees and Mavic is JIS, from my experience with them in the early 90s when I installed a bunch of them on Zap/Mektronic and the last click shifting Mavic group.

"But instead of repeating all this second hand stuff that may or may not be correct"

How is Sutherlands, Sheldon and Phil Wood 'second hand'?

But 'spec' that Mavic crank you are trying to install. Unless it's new, the flats have been deformed anyway, regardless of JIS, ISO or WGS taper.

"First hand" would be what Mavic says it is, not an independant third party.

What was your experience when you installed Mavic cranks on ISO spindles? Everyone knows you can mount an ISO crank on a JIS spindle - that doesn't mean it is correct.

I don't understand why you are being so dismissive. Mavic being ISO or JIS has been an item of contention for some time, it doesn't make much sense for a French crank company to not use the French ISO standard, and everything you're quoting is not a primary source. Isn't it possible that bad info got out there, and stuck?

Have you ever measured a Mavic BB spindle for yourself?

SPOKE 01-15-2012 04:38 PM

All these questions can be answered/settled if we could actually see the engineering abstracts that define these tapers.
What I do know is that there is a tolerance specified for each dimension. When you take into account the tolarences I'm certain that a basic 2 deg taper (4 degree included angle) my actually measure some degree more or less than the basic 2 degree taper we are talking about.
The basic differences of the JIS & ISO tapers is the length of the taper and the starting width across the flats of the small end. The missing elements are the tolerances specified by the actual standards and "possibly" any proprietary changes a manufacturer might choose to make for whatever reason.

shiftyfixedgear 01-15-2012 04:51 PM

Mavic bb confusion and over-confidence in measurements
 
Dear Kontact,

I trust the advice of people like Oulde Potatoe, Phil Wood and Co; Saint Sheldon Brown (RIP), and Saint Howard Sutherland much more than the so-called accuracy of someone's "precision internet measurement" claims. :)

My dos-centavos advice on matching the typically sloppy-tolerances of 4-flat BB axles to typically sloppy-tolerances on Crankarms : if the axle wiggles like a loose tooth then try another axle or rotate the crank on the axle and notice how it feels different in different positions. Welcome to the real-world of accurate and precise engineering in the bike world. Fitting cotterless cranks to bb axles and then trying to place the chainrings where you want them to be WRT chainline and chainstay clearances is a world where experience and trial-and-error play as much (or more) of a role than the layman's attempt to pigeon-hole cranks and bb's into simple ISO vs. JIS taper differences.

Oh what do I know ? I spent twenty-plus years in the trenches of bike repair and bike-building in some amazing shops back in the heyday of square bb axles. The confusing and frustrating complexities of the design makes it obvious why Shimano (and then others) abandoned the design. Now the pro's and cons of all the new designs . . . well, that is enough to sometimes make people want to give up and go back to something familiar (even if it isn't neccesarily better or optimal).

Kontact 01-15-2012 09:04 PM

Quote:

Originally Posted by shiftyfixedgear
Dear Kontact,

I trust the advice of people like Oulde Potatoe, Phil Wood and Co; Saint Sheldon Brown (RIP), and Saint Howard Sutherland much more than the so-called accuracy of someone's "precision internet measurement" claims. :)

My dos-centavos advice on matching the typically sloppy-tolerances of 4-flat BB axles to typically sloppy-tolerances on Crankarms : if the axle wiggles like a loose tooth then try another axle or rotate the crank on the axle and notice how it feels different in different positions. Welcome to the real-world of accurate and precise engineering in the bike world. Fitting cotterless cranks to bb axles and then trying to place the chainrings where you want them to be WRT chainline and chainstay clearances is a world where experience and trial-and-error play as much (or more) of a role than the layman's attempt to pigeon-hole cranks and bb's into simple ISO vs. JIS taper differences.

Oh what do I know ? I spent twenty-plus years in the trenches of bike repair and bike-building in some amazing shops back in the heyday of square bb axles. The confusing and frustrating complexities of the design makes it obvious why Shimano (and then others) abandoned the design. Now the pro's and cons of all the new designs . . . well, that is enough to sometimes make people want to give up and go back to something familiar (even if it isn't neccesarily better or optimal).

I've been working in the bike industry off and on since 1990. I'm not just some idiot with a set of calipers and an axe to grind. My boss, who has protyped and introduced a lot of cycling components over the years, also looked at what I was seeing and agreed that Mavic has always been ISO. He raced on SSC stuff in the mid-80s.

The truth of this matter is that there has never been good information put out there, and some of the accepted sources do, occasionally, have inaccuracies. Repeat them often enough and they become "truth".

The only people that can say definitively what they are is Mavic, but I'm here to tell you what a side by side comparison looks like. Here's somebody else that saw a something similar:
http://www.cyclingforums.com/t/22707...vic-631-cranks

I don't "know better" than anyone, but I do have the darn things sitting on a bench in front of me, and the differences are pretty obvious.

oldpotatoe 01-16-2012 07:33 AM

Quote:

Originally Posted by Kontact
"First hand" would be what Mavic says it is, not an independant third party.

What was your experience when you installed Mavic cranks on ISO spindles? Everyone knows you can mount an ISO crank on a JIS spindle - that doesn't mean it is correct.

I don't understand why you are being so dismissive. Mavic being ISO or JIS has been an item of contention for some time, it doesn't make much sense for a French crank company to not use the French ISO standard, and everything you're quoting is not a primary source. Isn't it possible that bad info got out there, and stuck?

Have you ever measured a Mavic BB spindle for yourself?

I never installed a Mavic crank onto a smaller than JIS, ISO spindle, cuz it's JIS.

Why am I being so submissive? Because I haven't seen a Mavic crank or BB is some time and so it really isn't a big deal to me. But if I see one and they need a BB, I recommend a 113mm UN series BB.

French using JIS? Sugino and Suntour using ISO?? OMG, dogs and cats living together!

I'm tapping outta this 'un.

But call Mavic, ask for Skip, he's been there the longest, the best inside guy, he'll probably know...

merckx 01-16-2012 10:22 AM

back in the day we used jis for a perfect fit.

Kontact 01-18-2012 01:11 PM

Talked to Skip today - nice guy. Apparently, I wasn't the only one to ask this question - someone called two days ago.

The Mavic 610 BB spindle is NOT JIS, and trying to put a Shimano crank on one is likely to destroy the crank when it bottoms on the spindle shoulder.

Skip didn't recall anything that actually said "ISO", but said that a C-Record era Victory spindle was an A fit for the Starfish 631 crank, and a Nuovo Record spindle was an A-. Shimano was not even considered a B fit. This fits with the information out there that Campy wasn't technically ISO until post C-Record, and there was some minor variations in their spindle tapers.

Of course, any ISO crank can be mounted on a JIS spindle. How good an idea that is has been hotly debated by Jobst Brandt, Sheldon Brown and others, but it wouldn't be a first choice if there are better fitting spindles out there. Whether that killed Gummee's crank is also debatable, but Mavic certainly wouldn't have warrantied the crank had they known that the crank had been mated to a sub-B fit.

It also looks like you can make "precision internet measurements" successfully with good tools, and that they might provide better information sometimes than secondary sources like Brown and Sutherland. Primary sources are always the best - read the manual, call the manufacturer if there is any doubt.

Thanks.


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