I just won a set of dura-ace cranks and need to find a matching bottom bracket. I’ve been searching and so far I’ve read that it’s 107mm ISO taper and 108mm JIS taper. Which one is it exactly I was considering getting the miche primato bb bc it’s 107 and I’ve read good things about it and it’s on the cheap side. I’ve also read about the shimano un54 being compatible too.
I’ve also read that taper kind of doesn’t matter all that much as long as you stick with one. It just may cause minor chainline problems bc the cranks won’t sit on the spindle all the way. Is this true?
Can anyone shed some light for me. Sorry if it’s been discussed already.
Shimano/most modern Japanese shit=JIS
Campagnolo/some high end Sugino/other Italian shit=ISO
This might be true if you have a cartridge bb, but I ruined a awesome crankset this way, running an ISO crank on a JIS bb. Now the tapers are fucked and it bottoms out.
Pretty sure all Shimano square taper stuff is jis.
UN54’s are pretty cheap and maintenance free. I have them on 2 of my bikes and have never had a problem. The plastic cup non-drive side cup is kind of cheesy but I haven’t had one break on me.
Sugino 75’s are ISO. There might be something to your idea that all keirin cranks are that way. I would look further into this before putting my nice cranks into a potentially cheesy setup. Sheldon says it’s ok to swap tapers but I’d just prefer to have everything set up the way god intended.
Yeah, I’m going with ISO, too. Simply because the Japanese were copying Campagnolo stuff when they designed the high-end Dura Ace, Sugino and Suntour stuff.
I just remember reading a long thread on portland fixed about alternatives for Sugino 75 BB and people were talking about mixing tapers and pretty much as long as you dont keep going back and forth between them its fine. If its ISO and you use JIS but stick with JIS for the life of the arms then youll be fine. Its mainly just that the crank arms wont fit fully flush like they would on the correct taper, possibly causing minor chainline problems.
I wanna use the right BB and all i just have no idea which taper to get i cant find anything really, the UN54 is JIS and im pretty sure the NJS Dura Ace BB are all JIS but all i could really find is the Dura Ace NJS BB for the Sugino 75s.
There is the Shimano Dura-Ace 7610 which is JIS 68x110mm thats i guess the NJS bb for the square taper version. But now thats 3 different spindle lengths so far.
Yea thats the conclusion im coming to also, but now reading a thread someone said all DA NJS cranks are ISO. So complicated. I think im just gunna go with the UN54 or just go with the Miche.
The Miche bb’s aren’t crap, but you pretty much have to loctite them in to prevent the cups from coming loose. That, or constantly check them, which involves contantly taking the cranks on/off and deforming the taper.
Yea I understand, I’m probably just going to pick up the UN54 BB for now and possibly save up for a better one down the road. I saw a bike on velospace running DA cranks with 75 bb which are ISO taper. So I’ll just save up for one of those if the UN54 sucks.
There’s nothing wrong with the UN54. It’s cheap, which is actually something very right. If it doesn’t bork your chainline and you are comfortable with a mismatched taper, give’r.
They’re ISO, but use whatever. I have a set, and I’ve run them with the matching 7610 BB (ISO), a 107mm Shimano UN BB (JIS), and a 110 TA Axix Light Pro BB (ISO). They all work fine.
