Cook Brothers RSR Crank Questions

@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...

Here goes @pw_pw_la

I looked at a couple of Syncros BB's.. one for sale here via Tomato which was 131mm spindle and JIS taper.. he measured the size at the end of the taper which was 12.66mm, the exact same size as the Shimano i had just removed.. so yeah JIS.

The other was advertised as JIS with 127mm spindle via ebay from this seller based in Germany, he took the same measurement at the end of the taper with his cheap digital vernier which read 12.6mm but it looked like the measurement was taken part way down the taper, so i asked him to do it again.. he took the same measurement with his non-digital vernier, locked it out and wouldn't fit the end of a Shimano spindle so i was pretty confident it was actually ISO.
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When it was delivered the driveside lockring^ was seized tight (thanks for mentioning that!).. i had zero chance of removing it at home but thankfully i have a workshop at my disposal and managed to get it off without stripping the threads..I checked the size at the end of the tapers in 4x places and they vary between 12.5 and 12.57mm (it's super lightweight) :cool:

The BB can be used in either 68 or 73mm shell, I read that one could offset the Syncros thread within a 68mm shell using the extra 5mm thread giving me that extra bit of clearance i needed for the small chainring but when i measured it, the spindle is actually offset by 4mm in favour of the driveside.. perfecto!

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Which puts the extra few mm's of thread on the non-driveside and because of this clever design the longer spindle flex is reduced massively

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Its silky smooth but it is tight in there, after some fiddling..i set the chainline to give me 1mm clearence between the small ring and the chainstays and the high limit screw locked down to stop the front mech rubbing on the inside of the crank arm.. again, there is only about 1mm clearence with the high limit screw stopping it moving out any further.. probably explains why CBR started notching out the back of the arms..

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Took it for a spin and every gear works perfectly with a small amount of chain rub on the mech in the top and bottom gear but i use that lever in friction shift so i can give it a little tweek if needed.

In homage to that little sheep.. i keep my lithium grease in a Mint Sauce jar 😁

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Lovely stuff!

And boy do those Syncros BB's look good, especially in conjunction with that crank!
 
Just adding this as the link to bikepro no longer works.



Cook Brothers Cranks​

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COOK BROS. RACING CBR CRANK ARM SET​

These cranks are machined from solid pieces of 7075 T6 aluminum stock. Each of the arms is turned on a lathe to produce the tapered shape, with a 37.72mm diameter ball at the B/B and a 29.14mm diameter ball at the pedal end. The ball shapes are then milled flat with the specific angles required for the spider and pedal and B/B spindle installation. The pedal end ball is drilled through and tapped with 9/16" by 20 threads per inch threads for the pedal spindle. The crank arm dust cap hole is bored and tapped with 22mm by 1mm threads, (no caps are provided with this crank arm set). The square B/B spindle hole is milled with 2 degree tapered sides when the rear of the arm is machined. The back side of the arm is drilled and tapped for a Torx bolt that holds the spider to the rear of the arm. The rear of the large ball has three steel pins driven into it. These pins are used to fix the precise position of the spider on the arm before the Torx bolt holds them together. The crank arms are high polished, and then anodized. After anodizing, the Cook Bros. logo is finely engraved on the face of each arm. The spider is machined from a single piece of 6.63mm thick aluminum plate stock. It is cut to shape, then drilled and tapped for the chainring bolts where needed. The arms have a 6 degree offset for chainstay and ankle clearance, and come with a triple chainring spider (adapter) with threaded inner ring bolt holes. The chainring bolt pattern is the standard 110mm outer, 74mm inner. The crank arm set will work with any standard 2 degree tapered bottom bracket, and naturally Cooks recommends their own sealed bearing bottom bracket. The crank arms come anodized in Black, Purple, or Silver with the spider anodized in Black. We stock them in 171mm, 176mm, or 181mm lengths. We found the CBR Mountain cranks to have a Bike-Pro Q measurement of 168mm. Cooks CBR cranks come as right arm with spider, left arm, and a set of five steel inner chainring bolts with aluminum spacers. Chainrings, the double chainring bolt set, crank bolts, and crank arm caps will be needed separately. The 176mm arm set with spider in Black weighs 507.5 grams. The inner bolt set provided weighs an additional 35 grams. Be sure to specify color and length.



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COOK BROS RACING RSR SERIES CRANK ARMS​

The Cook Bros. Racing RSR cranks are similar in style to the Cooks CBR arms, (the same aluminum stock, 7075-T6) and are made using the same manufacturing techniques, however there are some important design differences. The arm dimension is slightly smaller in diameter, and they have a half-round shaped slot milled down the back of the arms. The milling is to create greater clearance for smaller chainrings, front derailleurs and generally to produce a lighter crank. The left arm of the CBR set, in a 176mm length, weighs 224.5 grams, while the 176mm RSR left arm weighs just 188.5 grams. The 176mm right arm of the CBR set weights 283 grams while the 176mm right arm of the RSR set weighs 248 grams. The spider has been reworked, having all excess aluminum milled away to reduce any extra weight. This crankset is compatible with all 2 degree tapered bottom brackets, and uses the standard 74mm and 110mm bolt pattern. The crank arms are anodized in Blue, Black, Purple or Silver, with the spider anodized in Black, and come in 171mm, 176mm, or 181mm. We found the RSR cranks to have a Bike-Pro Q measurement of 167mm. Cooks RSR cranks come as right arm, with spider, left arm and a set of five steel inner chainring bolts with aluminum spacers. Chainrings, the double chainring bolt set, crank bolts and crank arm dust caps will be needed separately. The 176mm arm set, with spider, in Silver, weighs 436.5 grams. The inner bolt set provided weighs an additional 35 grams. Be sure to specify color and length.

COOK BROS. HYPER-C MOUNTAIN CRANK ARM SET​

A compact version of the RSR arms is available, achieved by making the right arm with a spider that has 58mm inner bolt pattern and a 94mm outer chainring bolt pattern. These Hyper Drive-C compatible arms are slightly lighter and compatible with all 2 degree tapered spindle B/B's. They are also made in Black, Lavender, or Silver anodized finishes, with the spider anodized in Black. The Cooks Hyper-C cranks come as right arm, with spider, left arm, and a set of five steel inner chainring bolts with aluminum spacers. Chainrings, the double chainring bolt set, crank bolts and crank arm dust caps will be needed separately. The inner bolt set provided weighs an additional 35 grams. Be sure to specify color and length.






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COOK BROS. PCH ROAD RACING CRANK ARM SET​

Cook Bros. makes a Road model of the RSR cranks using a 130mm bolt center diameter pattern. Machined of 7075-T6 aluminum, the PCH crank arms are made using the same techniques involved the RSR Mountain arms, and have the milled slot on the rear of the arm. The PCH cranks are made anodized in Black, Lavender or Silver with the spider anodized in Black. We found the PCH cranks to have a Bike-Pro Q measurement of 160mm. The PCH cranks come as right arm with spider and left arm. Chainrings, the double fixing bolt set, crank bolts and crank arm dust caps will be needed separately. The 171mm PCH cranks weigh 436.5 grams. Made in USA, specify color and length.


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COOK BROS. "E" CRANK ARM SET​

The Cook Bros. "E" series cranks are more traditional in their styling. They are machined from 7075-T6 billet aluminum. Unlike the other Cooks arm sets these have a rectangular cross section, not round, and the E cranks use a replaceable, user installed spider. At the pedal spindle, the arm is 27.83mm, it reduces above the pedal to 18.5mm. On the left arm, at the B/B spindle area widens to 37.5mm. The arms are 14.14mm thick at the pedal spindle and thicken to 26.4mm at the B/B spindle. The right arm has five round posts protruding from the back of the arm. These five posts are drilled and tapped for the inner fixing bolts to anchor in. The spider with the outer fixing bolt pattern drilled into it also slides over these five posts. Custom aluminum spacers used with the inner fixing bolts tighten down over the machined plate aluminum spider. The right arm has four stubby extensions that the posts are fastened to. The extensions lie perfectly over the spider. The posts incidentally are positioned so that only a 58mm bolt center diameter can be used for the inner chainring. There are three choices of Bolt center diameter for the spider, either a 94mm BCD or a 110mm BCD or a 130mm BCD. At the moment, the arms are made only in a 175mm length, Cooks believes that they may introduce a 181mm version in 1995. The arms come anodized in Blue, Black, Grey, Lavender or Silver. The standard spider with the 110mm BCD weighs 47 grams, the 94mm spider weighs 34.5 grams. The spiders are available in the same colors. We found the arms weighed 396.5 grams, and had a Bike- Pro Q measurement of 162mm. The inner steel bolts and aluminum spacers weighed 38.5 grams. The E crank set comes as right arm, left arm, spider, five steel inner fixing and the five custom aluminum spacers that hold the inner chainring and spider in place. Chainrings, the outer fixing bolt set, crank bolts, crank arm dust caps and will need to be purchased separately. Specify crank arm color, spider BCD pattern and spider color.



COOK BROS RS ATB CRANK 74/110mm BCD - 171-176-181mm -alloy- no B/B-Blue - Black - Grey - Purple - Silver - 435 g $ 149.99

COOK BROS E-CRANK 175mm
- Blue - Black - Green - Grey - Purple - Silver -or Judy (Canary) Yellow - spider included in 58/94 or 74/110 or 130mm bolt patterns - unlike our competitors, we continue to include the set of matching Cooks crank arm caps... an added $14 savings $ 209.99

COOK BROS RS HYPER-DRIVE-C CRANKS
- 171-176-181mm - 58/94mm BCD - Blue - Black - Purple - Red - Silver $ 149.99

COOK BROS
RINGS 94mm 32-34t colors $ 39.99

COOK BROS
RINGS 94mm 44-46-48t colors $ 54.99

COOK BROS CRANK CAPS
-Radius Perfectly Matches Cooks Cranks - Blue - Black - Grey - Silver - Purple - Green or Judy Yellow - PAIR $ 16.99
 
The other day after riding my Cook Bros equipped bike I noticed the drive side arm was loose, easy enough to remedy of course. Tightened up and good to go now. I must admit I am shy to torque Cooks down too much due to them been so prone to cracking and I check the cranks are snug before and after every ride.

Now my question: does anyone know the recommended torque one should use? I've been doing a bunch of digging but not been able to find this info so far. Alternately I'd appreciate a safe recommended torque from anyone who cares to share this based on experience.

Cheers
 
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

I’m glad it’s not just me then! 😬🤣👍🏼
 
Always used the Sugino or Syncros Ti version of these. Fit them with a spanner bolt/washer initially ( remove the locking bolt/washer ) then fit these and firmly test/tighten by hand with a normal length allen key ( so you cant over torque ) before any ride. Been using 6 sets since the 80s and never had an arm crack and they have been crash landed flat thousands of times. Over-tightening is the crank killer.
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