Ritchey Logic (by Sugino)
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Category:  Cranksets
Name:  Ritchey Logic (by Sugino)
Brand:  Ritchey
Model:  Logic
Years:  N/A
Country:  Japan
Weight:  714 grams (Spec),
Logic 175mm cranks with all included parts, weigh 714 grams
Added By: Catnap on 02/02/11
Updated By: movinyl on 09/08/12
Additional Photos - click for full size
Ritchey Logic (by Sugino)Ritchey Logic (by Sugino)Ritchey Logic (by Sugino)Ritchey Logic (by Sugino)
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Chainring CountDoubleBCD 110mm
BB StyleSquare Taper (JIS)Pedal Threads9/16" x 20 (English)
BB Length Flutes None
Lengths 170; 172.5; 175; 177.7; 180Arm/Spider MaterialAluminum Alloy
Front MarkingsRitchey LOGICBack MarkingsSugino
Extractor Threading 22x1mm (Standard)  
General Information
The Ritchey Logic crankset is made in Japan by Sugino (who also makes the cranks sold under the Specialized name), following Ritchey's specifications. The crank arms are among the first of Sugino's new cold forged products. Each of the arms is high polished by hand on the outer face, top and bottom sides, (the rear of the arm is lightly polished, the rear of the spider isn't at all) then clear (Silver) anodized. The arms have a flat surface for the face, top and bottom, making stress fractures easy to spot.

To reduce weight, one of the five arms on the spider section of the right crank arm, has been eliminated. The fifth arm on the Ritchey crank, actually exists on the back side of the crank arm itself, where the spider, and the arm meet. The crankset was designed with a low Q-factor as an objective. These Mountain cranks are said to have a 151mm Q factor, which is the distance from outer crank facing to outer crank facing with the two arms properly and securely fastened to a B/B spindle. The end of each arm, at the pedal end has the backside rounded slightly, to provide greater chainstay clearance. The left arm is forged with a point, leaving extra mass around the B/B spindle. This extra aluminum helps displace stress on an area historically prone to stress fractures.

Included with the cranks are chrome plated steel crank bolts that have affixed chrome dust caps. These bolts have an 8mm hex fitting for removal and installation. A steel washer is included for the cap/bolt to turn against reducing friction. The bolt weighs 16.5 grams, the washer another 2.5 grams. Using a crank arm pulling tool (Park CCP1) will still be necessary to remove the arm without damage. The crankset comes with Silver anodized aluminum chainrings, and all necessary fixing bolts.

The outer chainring is die-cut from 3.66mm thick aluminum plate, then turned on a lathe to taper the teeth, and then the teeth area to 2.06mm thickness. The outer chainring has an anti-jam pin pressed into it at the crank arm, to prevent the chain from bunching up between the arm and rings in an overshift. The middle is die cut from 3.30mm aluminum plate, turned on a lathe to taper the teeth and thickness to 2.03mm. The inner made the same as the middle. The chainrings use the standard 74mm and 110mm fixing bolt pattern. Because the "fifth arm" of the spider is really the crank arm, standard outer chainring replacements with an anti-jam pin won't have the pin usefully line up correctly on the Logic Crank. Replacement with a "Ritchey" or a 110mm BCD outer designed for fifth arm cranks will be necessary to maintain the anti-jam pin functionality. The Logic Mountain cranks come with nickel plated steel middle outer fixing bolts and nuts. The inner set of fixing bolts is also nickel plated steel.

The cranks will work with any 2 degree, tapered spindle, bottom bracket. Provided with 24-36-46 tooth chainrings. Logic cranks come as right arm, left arm, three chainrings, all the required fixing bolts, and a set of crank cap/bolts. Logic 175mm cranks with all included parts, weigh 714 grams. The steel crank arm cap set weighs 38.5 grams a pair.

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Additional Resources
Resources:Reference & ChartsGear Calculator
Brand Information(click to expand)
 Founded by Tom Ritchey who to this day is both the president and lead designer.  First known for his frames, today the Ritchey name is just as well known for components for road and mountain alike.
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