 |  | | | |  | |  |  | Cotterless Bottom Brackets ISO vs. JIS |  | |  |  | |
 Posted: Mon Oct 03, 2011 12:27 am |
 |
|
| verktyg |
|
 |
|
| Joined: 14 Jan 2007 |
| Posts: 2814 |
| Location: SF Bay Area |
|
|
|
Greetings,
I've been meaning to put this information together for a long time. I finally got around to it while building up my late 60s Interclub frame to use as a single speed (NOT A FIXIE  ) wet weather beater.
The bars are too high, they're just in temporarily (my usual safety comment).
There's a lot of fretting over ISO vs. JIS bottom brackets. This little photo essay should answer some questions...
http://www.flickr.com/photos/28267220@N05/sets/72157627678462359/
Put simply. new or almost new crankarms probably work best using the spindles that they were designed to mount on.
I've NEVER seen any accurate published specifications for ISO and JIS bottom bracket spindle dimensions!!!
There are standardized NJS dimensions for Japanese Keirin bicycle components so that all of the bikes are the same and no rider has a technical advantage. I've always equated track racing in Japan with thoroughbred horse racing complete with parimutuel betting! 
Once a crankarm has been installed and removed several times, the malleable aluminum stretches and the internal square gets larger.
If they were overtightened or run with loose mounting bolts, the square may become too big and unusable.
The original Phil Woods sealed bearing bottom brackets came in "one size spindle taper fits all", only the overall widths were different.
What I' found (and said) over the years is that the manufacturing tolerances on classic bicycle components were so wide open that you can't depend on published specifications.
For example I show 2 different Stronglight 118 spindles, an older one from the 70s and a later version. They were the standard spindle for Stronglight double chainring cranks from the 1940s on.
They are both 117.9mm long but the 2° tapers per side are different! The chrome plated later version fits the Stronglight 104 crankarm. The taper on the earlier one is smaller and goes in too far!  (see pictures in above link)
BTW, what I ended up using on this bike was a Shimano JIS 112mm spindle and metric bottom bracket.
STANDARDS
ISO = International Standards Organization (usually equated to metric standards except for bikes)
JIS = Japanese Industrial Standards
NJS = Nihon Jitensha Shinkōkai - the governing body that oversees Japanese Keirin bike racing
DIN = Deutsches Institut für Normung - German industrial standards which don't necessarily apply to bikes but FYI (and in celebration of Oktoberfest) 
So if it fits, it works... That's why putting bikes together is called "FITTING".
Remember they are "HAND CRAFTED" creations not Swiss watch movements!
PS: here's another link to Stronglight 104 cranks. these were used on a few Gitanes in the early 80s.
http://www.flickr.com/photos/28267220@N05/sets/72157627635828586/ |
|
_________________
Chas.
SF Bay Area, CA USA
==============
1984 Criterium
1969 TdF
1971 TdF
1974 TdF
1984 TdF x 2 Bikes
1970 SC
1971 SC
1972 SC
1984 SC
1984 Team Pro
1985 Professional
1990s Team Replica |
|
|
|
|
|
| |  |  | | | |  |  |
| | | | | | | | | | | | | | |
| Posted: Wed Oct 05, 2011 2:13 pm |
|
|
| tchikiboum92 |
|
|
|
| Joined: 02 Sep 2011 |
| Posts: 14 |
| Location: PARIS FRANCE |
|
|
|
want more informations about keirin NJS standards?
search TOMITY in google, he is your keirin alter-ego!!! tracking for thousands miles
3Rensho drillium
authorised NJS frame builders list
tomity
 |
|
|
|
|
|
|
| | | | | | | | |
|
