Cook Brothers RSR Crank Questions

Excuse the thread jacking.. I've got similar Q's a bit of summing-up, some musings and occasional ramblings.. so why not keep it all in one place

I'm removing a Middleburn crank with 2x chainrings from my RC200 and replacing it with a CBR RSR with 3x chainrings.
The existing BB is Shimano JIS x 113mm spindle.

All tapers are nr perfect, the Middleburn crank arm when pushed (by hand) onto the JIS taper sits like this
fullsizeoutput_3603.jpeg

The CBR sits like this
fullsizeoutput_3604.jpeg

Re- Middleburn.. the distance from the thread recess to the end of the spindle is 2.2mm (we'll call this distance A) it was probably closer to 1mm before i pulled the crank.
fullsizeoutput_3607.jpeg

Same distance on the CBR (we'll call this distance B) is 4.5mm so it does seem that @M-Power is right and the RSR should be mounted on ISO or preferably their own BB

There are so many conflicting viewpoints around the interwebs!!.. even checking this thread it looks like the CBR crank sits a lot further down the JIS taper than mine does... not sure if this is RSR version or not?

Now here's the fly in the ointment.. obv's i need a different BB and measuring the chainline a 127mm spindle length should work (a'la MP) but when the 113mm BB was in situ, i pushed the CBR crank onto the spindle until the smallest chainring hit the frame, 'distance B' measured 7mm so 7mm +7mm +113mm = 127mm so if i used a 127mm ISO BB the smallest chainring could be hitting the chainstay, if i used a 127mm JIS BB the spacing would move the chainline out but give the clearence needed to move the chainring away from the frame.. BikePro recommend 122.5 ??

With the smallest chainring hitting the frame i have a 49mm chainline at the front and 45mm at the back.. which looks about right.

Here in the UK i can buy a 127mm Shimano UN-300 for £20 from LBS but i'm struggling to find a 127mm ISO BB, i don't mind paying for a decent BB if i'm 100% confident that i've got the sizing right..

Folks are running CBR RSR on RC200's so what BB are they using??

Bonus crank shot

fullsizeoutput_3608.jpeg

Opinions welcome?
 
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I have a threaded Syncros Ti 127mm iso BB for my RSRs in my Wicked Lite. These are not cheap ~ @ £160. Similar quality press fit bearing iso axles work out cheaper £30-60 by Cooks and other suppliers and can be found on Ebay from time to time.
 
Thanks MP.. i've been looking at Royce who have all spindle lengths in ISO off the shelf and similar pricing to your Syncros.. I don't mind the cost as such if i'm 100% confident that 127mm ISO is the correct length.. i would know for sure if i could slot the crank onto the spindle and see where it sits on the taper.. so if i buy new i could return as opposed to ebay where i could pay international shipping +vat to find it doesn't work out.

I've spent a few £££ on this bike so a decent BB would only be in tune with the rest of the build.
 
@Betsy Will you post your findings either way?

Curious to see how it all goes.

I'm currently putting an RSR on the ti spindle they came with.

Although I don't actually know if it's ISO or JIS! Need to ask my biddy who's building it for me to check...
 
Thanks MP.. i've been looking at Royce who have all spindle lengths in ISO off the shelf and similar pricing to your Syncros.. I don't mind the cost as such if i'm 100% confident that 127mm ISO is the correct length.. i would know for sure if i could slot the crank onto the spindle and see where it sits on the taper.. so if i buy new i could return as opposed to ebay where i could pay international shipping +vat to find it doesn't work out.

I've spent a few £££ on this bike so a decent BB would only be in tune with the rest of the build.
Its 127 on various FATs i have owned over the years bit i cant say with certainty if its correct for your bike.
 
Nobody?

Alright.. ive made a model of a 68mm BB with a 127mm ISO spindle
fullsizeoutput_3609.jpeg

Check the taper
IMG_4236.JPG

1mm below
fullsizeoutput_360b.jpeg

Fitted
fullsizeoutput_360a.jpeg

Pushed the crank on and just as i suspected.. the smallest ring hits the frame
IMG_4240.JPG

So i need a 130mm ISO (or in the very least 128mm) or a 127mm JIS BB..

Does anyone have a 68mm x 130mm ISO BB for sale??
 
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Nobody?

Alright.. ive made a model of a 68mm BB with a 127mm ISO spindle
View attachment 658510

Check the taper
View attachment 658513

1mm below
View attachment 658514

Fitted
View attachment 658511

Pushed the crank on and just as i suspected.. the smallest ring hits the frame
View attachment 658515

So i need a 130mm ISO (or in the very least 128mm) or a 127mm JIS BB..

Does anyone have a 68mm x 130mm ISO BB for sale??
You need more free time. To do more of this. And copious amounts of drink to fuel this lunacy
 
Nobody?

Alright.. ive made a model of a 68mm BB with a 127mm ISO spindle
View attachment 658510

Check the taper
View attachment 658513

1mm below
View attachment 658514

Fitted
View attachment 658511

Pushed the crank on and just as i suspected.. the smallest ring hits the frame
View attachment 658515

So i need a 130mm ISO (or in the very least 128mm) or a 127mm JIS BB..

Does anyone have a 68mm x 130mm ISO BB for sale??
Why didn't you just make it 3mm longer 🤔
Bit of lignum possibly might last a bit longer?
 
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