Cook Brothers RSR Crank Questions

[Once A Hero]

Nice one @kingoffootball it was that discussion you linked that led me to think ISO BB.
Why does the old stuff here to be so complicated

Back in the nineties I don't recall being aware of JIS or ISO, I still don't know the difference if I'm honest (not spent any time looking in to it), and therefore I just choose a bottom bracket of correct length for the cranks I'm using without giving a thought as to whether it is JIS or ISO.
Could it be that I have sets that are simply wrong and I just don't know it?
Would a JIS BB not even fit an ISO crank, or vice versa? Or is the difference so subtle that it doesn't actually matter?

I swear things are more complicated now, not just because of the passing of time, but because we interrogate things more and are learning things we've never known - or got by without needing to know...

I'll not mention English and Italian threads either. Oops.

Yours Blissfully Unaware,
Once A Hero

 

[kingoffootball]

Back in the nineties I don't recall being aware of JIS or ISO, I still don't know the difference if I'm honest (not spent any time looking in to it), and therefore I just choose a bottom bracket of correct length for the cranks I'm using without giving a thought as to whether it is JIS or ISO.
Could it be that I have sets that are simply wrong and I just don't know it?
Would a JIS BB not even fit an ISO crank, or vice versa? Or is the difference so subtle that it doesn't actually matter?

I swear things are more complicated now, not just because of the passing of time, but because we interrogate things more and are learning things we've never known - or got by without needing to know...

I'll not mention English and Italian threads either. Oops.

Yours Blissfully Unaware,
Once A Hero

There lots of places that explain this well but basically ISO and JIS will fit together, but give a different chainline as the cranks will either be further in or further out, depending on whether it's JIS crnaks on ISO or the other way around. Additionally, there can be occassional problems with tapers bottoming out.

 

[Betsy]

Thanks for the contributions gents.. i knew you'd Poirot it eventually.

@Once A Hero.. there was also an element of ignorance in the 90's (speaking of myself here) the extent of my consideration would be 'if the part fits, its the correct part' nowadays we reach for the internet to research every eventuality, asking questions which may or may not need answering and being overinformed is creating headaches we wouldn't have ordinarily had.

Here's to ignorance!!

 

[Canuckbiker]

Back in the nineties I don't recall being aware of JIS or ISO, I still don't know the difference if I'm honest (not spent any time looking in to it), and therefore I just choose a bottom bracket of correct length for the cranks I'm using without giving a thought as to whether it is JIS or ISO.
Could it be that I have sets that are simply wrong and I just don't know it?
Would a JIS BB not even fit an ISO crank, or vice versa? Or is the difference so subtle that it doesn't actually matter?

I swear things are more complicated now, not just because of the passing of time, but because we interrogate things more and are learning things we've never known - or got by without needing to know...

I'll not mention English and Italian threads either. Oops.

Yours Blissfully Unaware,
Once A Hero

As Kingoffootball mentioned, the distance the crank gets snugged up may be different when mixing and matching so a given spindle length may or may not be the right one especially when ordering and you can't test first and easily return. I too had no clue about these standards BITD. If my eBay seller ever ships my Cooks (he sure is taking his time) I'll soon have them to experiment with and return comment on using JIS (Shimano) and what spindle length works for my 93' Cannondale BOTE. Fortunately I have a bunch of unworthy (low end/rusty) cartridge units which are different lengths to play around with to see whether crank ends and chainrings clear by just enough before ordering something nice in the right length

 

[M-Power]

Got 6 sets of RSRs, my fav cranks. All ISO taper and 127mm BB on all the bikes I fit them on. ISO taper cranks often end up being forced onto JIS taper BBs to get the correct chainline. Theres a risk of cracking if you push them on too far and for sure weakening them.

 

[Betsy]

Thanks MP, one last question.. what the hell are you doing, still up at 2:44am?

 

[Canuckbiker]

Got 6 sets of RSRs, my fav cranks. All ISO taper and 127mm BB on all the bikes I fit them on. ISO taper cranks often end up being forced onto JIS taper BBs to get the correct chainline. Theres a risk of cracking if you push them on too far and for sure weakening them.

Thanks M-Power, I'm glad to hear this. Was planning to use JIS tapers but better reconsider. These are bucket list cranks for me and the last thing I want to do is compromise the integrity of them. Being machined only and not forged I expect they are weaker than other 30 year cranks anyway.

I'll still wait for my cranks to get an idea in spindle length, I want them a tight top the frame as possible without being too close. I have a campy BB that will surely be too short but curious to see how far the taper sinks in when I do some test fitting. Campy is ISO typically I believe? It's an 80s C-Record unit.

 

[kingoffootball]

 

[M-Power]

@ Canuckbiker. The RSRs are pretty strong. I have been around Europe a few times touring on them and hammering jumps for over 30yrs but im always careful to check they are tight before any big ride and never over tighten them on the tapers, which people can do. That being said they are really CX cranks imo, not for endless bunny hopping etc but the BMX crew might disagree

 

[Canuckbiker]

@ Canuckbiker. The RSRs are pretty strong. I have been around Europe a few times touring on them and hammering jumps for over 30yrs but im always careful to check they are tight before any big ride and never over tighten them on the tapers, which people can do. That being said they are really CX cranks imo, not for endless bunny hopping etc but the BMX crew might disagree

Thanks M-Power, good to know. Like all of my 90s vintage collection the bike these go on will not see any heavy duty use, just the mellow trails I figure they were designed for back in the day.

I had a real good conversation this morning with my eBay seller from Maryland. He's got some sweet bikes, I told him to check out the RB site. He told me that he only ever used Shimano bottom brackets with his Cooks.

I'm wondering if it's safe to try but just be careful not to tighten too much?

The preferred taper question is getting less clear to me. Campy BBs are definitely ISO so it's strange to see Cook's own directions saying use any 2 degree but not Campy, these look like CBR units but I assume RSRs would use the same BB?