Singlespeed & Fixed Gear - Sugino Messenger cranks + sugino 75 bb compatibility

Are these parts compatible? I've heard in some cases that ISO cranks and JIS bb's and vice-versa are compatible. Any know if these two are?

different tapers and different spindle lengths. if you want your chainline to be straight, no.

But if you want your chainline to be totally wonky, yes.

Are these parts compatible? I've heard in some cases that ISO cranks and JIS bb's and vice-versa are compatible. Any know if these two are?

I CANNOT believe this, but they may be.

http://www.sheldonbrown.com/bbtaper.html - " if you install a J.I.S. crank on an ISO spindle, it will wind up about 4.5 mm farther in than it would on a J.I.S spindle of the same length."

Since your Messenger crank needs a 103mm JIS BB, and your Sugino BB is a 109mm ISO BB, the extra length and the narrower taper may cancel each other out and leave you with a chainline that's within 1-2mm of perfectly straight.

Unbelievable.

I'd still buy a new 103mm JIS bottom bracket for $25, but you just may be in luck.

Holy crap!

I CANNOT believe this, but they may be.

http://www.sheldonbrown.com/bbtaper.html - " if you install a J.I.S. crank on an ISO spindle, it will wind up about 4.5 mm farther in than it would on a J.I.S spindle of the same length."

Since your Messenger crank needs a 103mm JIS BB, and your Sugino BB is a 109mm ISO BB, the extra length and the narrower taper may cancel each other out and leave you with a chainline that's within 1-2mm of perfectly straight.

Unbelievable.

I'd still buy a new 103mm JIS bottom bracket for $25, but you just may be in luck.

It might work, but it would messed up the cranks over time.

you need to be really careful of jis cranks bottoming out on an iso taper bb since the iso taper is so much narrower. it just depends on the specific cranks involved. you can try it and it MAY work, or it will bottom out and you will round off the taper on the cranks turning them into nice paperweights.

Why the OP wants to put a crappy crank on a high end bb is another question.

Most likely to try to correct the chainline issues associated with Sugino RDs.

OP - just use a 103mm JIS BB and you'll end up with a chainline that will be off by only 2 or 3mm (perfectly fine). I put a 1mm cassette spacer beneath the cog when helping a friend with his build and his chainline is pretty damn straight.

Or one could use eai cogs on formula hubs(close to 44 mm cl)wich is close enough.

I put a 1mm cassette spacer beneath the cog when helping a friend with his build and his chainline is pretty damn straight.

face palm

Why slap yourself? It's perfectly okay to use a cassette spacer as long as you don't go overboard and try using one that's too thick and eliminating a bunch of threads in the process. My friend's cog + spacer ended being just as thick as my EAI cog.

It's perfectly okay to use a cassette spacer .
no its not any mechanic that said that was okay is a dip. no bike shop will let a bike go out the door like that.

why?

Please explain why an EAI cog and a no name cog + 1mm spacer equaling the same width are so different. Are you afraid of seatpost shims and washers too?

ok. back on topic. sell the sg75 bb. get the correct one. buy a cup of coffee and a donut. dunk donut in said coffee. eat. repeat. have a merry day. yay.

Agreed. Donuts are good. So is coffee. Together, they are awesome. Happy New Year.