so i’m broke.
other than the obvious, what bb can i use with these cranks?
second thought…
chainlines never make sense to me.
75 cranks are supposed to create a 42mm chainline. so is the rear hub i have. 110.5mm bb’s can be found cheap and i guess that means the chainline would only be off by 1.5mm max? because bens says to use a 109-110mmm bottom bracket.
curious why theres a leeway of 1mm in the first place? esp since 75bb’s are 109mm… could it just be because who gives a fuck about 1mm?
wow this is a stupid thread.
miche primato i think works. its cheap and not durable, but sealed and gives a decent chainline. so i’ve heard.
[quote=“jasonm”]second thought…
chainlines never make sense to me.
75 cranks are supposed to create a 42mm chainline. so is the rear hub i have. 110.5mm bb’s can be found cheap and i guess that means the chainline would only be off by 1.5mm max? because bens says to use a 109-110mmm bottom bracket.
curious why theres a leeway of 1mm in the first place? esp since 75bb’s are 109mm… could it just be because who gives a fuck about 1mm?[/quote]
x = bb length
y = suggested bb length
42 + (x-y)/2 = chainline.
(i think.)
[quote=“conor”]
x = bb length
y = suggested bb length
42 + (x-y)/2 = chainline.
(i think.)[/quote]
interesting.
that would mean my chainline would be 42.75mm
0.75mm offset is better than the 1.5mm i had assumed. cool!!
Sugino 75s are ISO.
what you’re trying to do is match the front chainline(using the formula above) with your rear cog + hub combination. Check http://www.sheldonbrown.com/chainline.html#sprockets. IRO hubs are formula.
The Miche BB is ISO taper, and by far your cheapest choice($20), plus it’s adjustable, so you should be able to get a perfect chainline.
the 110.5mm bb you’re talking about is probably JIS taper, so according to sheldon:
“If you install an ISO crank on a J.I.S. spindle, it will sit about 4.5 mm farther out than it would on an ISO spindle of the same length.”
at
http://www.sheldonbrown.com/bbtaper.htmlapart from your chainline being off by a good amount, the JIS taper of the bb will supposedly deform your crank tapers over time, but who knows.
This is cheaper than the 75 bb but is basically the same thing without the njs stamps.
http://www.benscycle.net/index.php?main ... ts_id=3915For the record I have installed 75s for people on ISO bottombrackets (campy 111mm and Miche) and in both cases the taper was not the same as that of the 75bb and they did fit fine but less of the spindle actually fit into the crank. I have seen them installed on shimano bottombrackets as well with acceptable results too.
Despite what the taper/chainline geeks will tell you it seems either will work fine but the consensus is to stick with one and never switch types of spindles once the cranks are mated to one type.
This is a bit costly, but I’m wondering if anyone here has yet tried it. MY 75 BB is doing fine, but if I had to replace it, this is what I’d go with.
http://www.benscycle.net/index.php?main ... ts_id=3499I recently emailed Phil Wood about compatibility with sugino 75s, taper issues, etc. They said they reccomend their 110.5mm spindle with ISO taper for sugino 75s.
This seems odd for two reasons-
- 110.5 spindle does not set up an ideal 42mm chainline
- As mentioned above, I hear sugino 75s stick out farther on non-sugino ISO tapers.
thoughts? I’ve seen in other message boards people referencing an email someone recieved from phil wood reccomending a 108mm JIS taper. Maybe they have no idea.
[quote=“jensvejmand”]Sugino 75s are ISO.
what you’re trying to do is match the front chainline(using the formula above) with your rear cog + hub combination. Check http://www.sheldonbrown.com/chainline.html#sprockets. IRO hubs are formula.
The Miche BB is ISO taper, and by far your cheapest choice($20), plus it’s adjustable, so you should be able to get a perfect chainline.
the 110.5mm bb you’re talking about is probably JIS taper, so according to sheldon:
“If you install an ISO crank on a J.I.S. spindle, it will sit about 4.5 mm farther out than it would on an ISO spindle of the same length.”
at
http://www.sheldonbrown.com/bbtaper.htmlapart from your chainline being off by a good amount, the JIS taper of the bb will supposedly deform your crank tapers over time, but who knows.[/quote]
great post, thanks for the info brother.
the bb in question was definitely JIS and i was wondering about compatibility… just goes to show always check sheldon first.
sweet, i guess i’m going with the miche bb since i’m broke and its already snowing up here!
[quote=“colin!”]I recently emailed Phil Wood about compatibility with sugino 75s, taper issues, etc. They said they reccomend their 110.5mm spindle with ISO taper for sugino 75s.
This seems odd for two reasons-
- 110.5 spindle does not set up an ideal 42mm chainline
- As mentioned above, I hear sugino 75s stick out farther on non-sugino ISO tapers.
thoughts? I’ve seen in other message boards people referencing an email someone recieved from phil wood reccomending a 108mm JIS taper. Maybe they have no idea.[/quote]
from my ever growing knowledge of the tarck…
answers:
- the phil wood bb is adjustable just like the miche i was just recommended.
- ISO and JIS are compatible, but only in that “these things aren’t exactly compatible man” kinda way.
A 107mm JIS BBs, like the shimano UN-XX, are fine. Going from JIS to ISO tapers is bad for the crank, but if you pick one (even the wrong one) and stick with it for the life of the crank, it should be fine (or so sayth Sheldon)
This topic comes up time and time again, here and on that other forum. Every thread contains the following.
-
It always starts with someone wanting to save money and/or worried about riding an unsealed BB on the streets.
-
This leads to endless discussion of whether or not 75s are JIS or ISO. A stong concensus is never reached…different sources give different answers.
-
This is followed by mass confusion over BB compatability, chainline adjustability, and which BBs will work.
-
Inevitably, nearly everyone who has used 75s and has experimented with different BBs, concludes that using the Sugino 75 BB (the only one truly intended for these cranks), is the best option. Everything else results in half-assed configuration involving a less than perfect chainline, mismatched crank/BB tapers, and/or the cranks positioned asymmetrically from the median plane of the bike (such as with Phil BB, where the chainline is adjustable by moving the spindle further to one side).
I’ve fucked around with other BBs and I learned my lesson. Will other solutions work?..well, yes, in a half-assed sort of way. The Sugino BB is the only one that works in a completely satisfactory way. I’m tellin’ you, when you finally accept this, it is bliss. You no longer have to worry or care about the taper, the chainline, or compatibility…its all perfect. People have been using unsealed BBs for more than a century and they work fine.
I’ve never even overhauled my 75 BB and its as smooth as ever after a year and a half. As I mentioned above, if you want to save a few bucks, Sugino makes a “68 Mighty Track” BB which is the exact same thing as the 75BB, except that the cups lack NJS stamps.
I have no idea what BB is in my IRO SE frame - it was installed in my SS conversion and later moved over - but I bought the Miche and it will be swapped in soon. Whatever I have right now though, the chainline is fine. I’ll check the spindle markings when it comes out.