Cook Brothers RSR Crank Questions

[M-Power]

Cook Bros made quite a few different variants from the early 80s onwards. Fill your boots with this thread

https://www.mtbr.com/threads/the-cooks-crank-thread-to-end-all-cook-crank-threads.192813/

I dont want to set any hares coursing but check they dont have any hairline cracks when you get them ‘before’ fitting them See my pic. I had someone try to flog me some ‘bottle openers’ once, we went back and forth a few times until he finally showed me clear images of the crack, then I pulled out. Whats this line in my image with arrow ?

MP

 

[Canuckbiker]

Cook Bros made quite a few different variants from the early 80s onwards. Fill your boots with this thread

https://www.mtbr.com/threads/the-cooks-crank-thread-to-end-all-cook-crank-threads.192813/

I dont want to set any hares coursing but check they dont have any hairline cracks when you get them ‘before’ fitting them See my pic. I had someone try to flog me some ‘bottle openers’ once, we went back and forth a few times until he finally showed me clear images of the crack, then I pulled out. Whats this line in my image with arrow ?

MP

I'll let ya know hopefully this weekend, I still haven't received them but thanks for bringing it to my attention, fingers crossed I find no hairline cracks

 

[Canuckbiker]

Cook Bros made quite a few different variants from the early 80s onwards. Fill your boots with this thread

https://www.mtbr.com/threads/the-cooks-crank-thread-to-end-all-cook-crank-threads.192813/

I dont want to set any hares coursing but check they dont have any hairline cracks when you get them ‘before’ fitting them See my pic. I had someone try to flog me some ‘bottle openers’ once, we went back and forth a few times until he finally showed me clear images of the crack, then I pulled out. Whats this line in my image with arrow ?

MP

You called it, absolutely a crack. Lucky my seller has agreed to work with me and provide a partial refund, he doesn’t want them shipped back, I’m sure I can get a few bucks selling them as is to make up the difference locally, the drive side is perfect. I went ahead and ordered another set for a bit more money yesterday but warned the seller not to ship them until giving them a good once over, he did and found a crack at the square taper of the non drive side same as my first order. Good seller that he is refunded my money before shipping. I’m considering getting a set of CBRs. A bit heavier and I’ll miss the hollowed out backs but maybe they are less prone to cracks?

 

[Canuckbiker]

Anyone have a non drive side RSR 176mm they wanna sell? Color makes not difference

 

[M-Power]

Thats a shame Clear high res pics are a must when buying ‘any’ used cranks. The tapers and threads need to be in good shape. I had a set of CBRs once but they needed a 130mm Axle iirc which threw the chainline out and my knees didnt quite like it either. I would stick with the RSRs tbh as they are great cranks but I am biased.

 

[Canuckbiker]

All good points M-Power. CBRs also sweet looking and still may be a possibility but the hidden bolt design and others changes make the RSRs my favorite so will hold out for another set of RSRs I think. I found a small crack on the drive side after polishing yesterday as well. The cracks did not stop me from getting these babies ready for a photo shoot to see about fit, etc though.

To my surprise the Syncros titanium bottom bracket I have been using on my C-Dale which is only 108mm long seems to offer a bang on perfect fit/length. The C-Dale is a 93' M800 BOTE. Chainrings and crank arms clear with just the right amount of clearance.

I may come back to the polishing around the logo. After removing the anodization (I use Zep industrial purple degreaser which works well but is gentler than draino or other caustic liquids) I noticed the Cook logo stays only because there is a dull finish underneath around the letters. After sanding/polished and leaving the letters the dull bit could use some cleaner lines surrounding the logo

Okay, so dumb question: would I be completely insane to ride these? We are talking gentle riding, checking cracks before and after riding. The cranks would experience a fair bit of torque riding up steep hills. When bolting them down I did not torque the bolts as much as I normally would. The cracks did not show any sign of opening or changing during the process.

Either way I plan to keep eyes open for an uncracked set.

Now I know how amazing they look and really finish off my most blinged out ride. I'm still on the fence whether I will keep the M950 RD on but it seems to fit in for now.

 

[Canuckbiker]

Thats a shame Clear high res pics are a must when buying ‘any’ used cranks. The tapers and threads need to be in good shape. I had a set of CBRs once but they needed a 130mm Axle iirc which threw the chainline out and my knees didnt quite like it either. I would stick with the RSRs tbh as they are great cranks but I am biased.

Hi M-Power, I'm looking for your expert guidance. I am new to obsessing over Cook cranks other than drooling over them in the past, I thought RSRs all had a hidden bolt spider. I've seen this set of RSRs sold on RB years ago have a CBR looking spider with all five bolts visible but the backs of the cranks and pedal holes are milled out to save weight (and look cool) as the RSRs have. Are you able to let me know if these are the same arms as the cracked RSRs I purchased apart from the spider, therefore same bottom bracket compatibility? Or are these a different CBR variant?



Thanks for any advise you can offer

 

[M-Power]

“Okay, so dumb question: would I be completely insane to ride these? We are talking gentle riding, checking cracks before and after riding. The cranks would experience a fair bit of torque riding up steep hills”

It looks like that crack will continue to propagate outwards until it breaks free from the spider. The issue is not IF but when that happens. It could cause you a nasty injury or worse. The RSR crank arms are press fit and pinned in at the back of the spider, so it may hold for a while if you ride it ‘gently’ but imo I would never ride it.

These old RB ones look like another RSR variant, possibly an earlier one. I know my CBR ones flexed too much for me, also a related effect of a longer axle but they did look so pretty with the visible 5 arm slider. The RSRs I use only have the visible 4 spider arms and are nice and stiff which is important especially when climbing. I dont know for sure if they use the same axle length as I have never had a set like the old RB ones to compare. Honestly, Cooks made a huge number if variants over the years, hence that thread. I have stripped polished and had them reanodised and you can etch in the logos ( like a laser etched finish )with a glass etcher if you have time and a steady hand.They are great cranks but I would ONLY ride ones uncracked, use a correct width ISO BB, dont over tighten them but check they are not LOOSE before any ride and just enjoy.



MP

 

[Canuckbiker]

“Okay, so dumb question: would I be completely insane to ride these? We are talking gentle riding, checking cracks before and after riding. The cranks would experience a fair bit of torque riding up steep hills”

It looks like that crack will continue to propagate outwards until it breaks free from the spider. The issue is not IF but when that happens. It could cause you a nasty injury or worse. The RSR crank arms are press fit and pinned in at the back of the spider, so it may hold for a while if you ride it ‘gently’ but imo I would never ride it.

These old RB ones look like another RSR variant, possibly an earlier one. I know my CBR ones flexed too much for me, also a related effect of a longer axle but they did look so pretty with the visible 5 arm slider. The RSRs I use only have the visible 4 spider arms and are nice and stiff which is important especially when climbing. I dont know for sure if they use the same axle length as I have never had a set like the old RB ones to compare. Honestly, Cooks made a huge number if variants over the years, hence that thread. I have stripped polished and had them reanodised and you can etch in the logos ( like a laser etched finish )with a glass etcher if you have time and a steady hand.They are great cranks but I would ONLY ride ones uncracked, use a correct width ISO BB, dont over tighten them but check they are not LOOSE before any ride and just enjoy.



MP

Thanks M-Power. I bit of an update: my eBay seller (great guy) is giving me a full refund, after discovering the drive side had a crack I mentioned I would still be okay with a ¾ refund we originally talked about but he’s insisting on a full one.

I’ve ordered a second set with the five bolts exposed spider which look the same as the set sold on RB years ago I posted above (RSR milled out backs and pedal holes). I did some digging on Mombat. Their CBR ad from 1991 states that even the CBR uses DSB tech (damn short BB) and can run a 110mm spindle. More interesting in the below ad that Mombat feels confident is 1995 shows the “RS Standard” and “RS Hyper”, Hyper being the compact drive version. They are available in silver so I’m taking a guess the old RB sale and the ones I have ordered must be this variant c/w dark grey/pewter spider and RSR milling to save weight (and stiffer hopefully).



My Syncros titanium BB appears to be ISO (according to period details I can dig up) so I’m hopefull it’s the way to go with the new set. The 1991 CBR damn short BB ad statement gives me confidence Cooks kept this lower q factor going forward and my second Cooks order should work with the shorter spindle.

Here’s my second order (at a fair bit more expense). The seller was great. Pictures look crack free and after I asked, he examined them (my request) with a magnifying glass (his choice) and says he cannot see any cracks (fingers crossed). I like that they are silver already with not a lot of wear, should polish up nice:






I'll be going with my black rings already in hand.

One last question: grease or no grease on the tapers?

Thanks so much for all the feedback/advice!

 

[M-Power]

Looks good to me. Yeah, always put a bit of grease on the tapers and pedal threads.

Enjoy in good health

MP