SYNCROS REVOLUTION CRANK ARM SET
This is one of the few cranksets (the MRC cranks are the other) that combines different metals to deliver a crank arm set that is startling different. The arm section is made of Cro-Moly steel, has an elliptical shape and a hollow interior. The arm tapers from a 34.5mm width at the B/B spindle down to 22mm at the pedal spindle. The hollow, elliptical, tubular arms are drawn in their tapered shape by True Temper and sent to Syncros. Syncros makes separately of Cro-moly steel the pedal and spindle lug. The pedal lug is made of machined Cro-moly rod that is drilled, tapped with 9/16" by 20 TPI pedal threads and TIG welded to the bottom of the arm. The B/B spindle lug is made of Cro-moly steel tubing with a tapered and splined inner surface.
The Cro-moly steel arms are powder painted in a glossy Black. The actual piece that seats the B/B spindle is made of aluminum. This aluminum piece is machined from 7075-T6 aluminum rod drilled and tapped with 22mm by 1mm threads for the cranks arm dust cap. The piece is also drilled through then broached to make the square sides two degree tapered spindle fitting. This aluminum piece has tapered sides to just squeeze into the outer B/B spindle lug under machine pressing. Both arms have this aluminum core within the steel outer B/B lug. The aluminum piece is considerably larger on the right crank because the machining process leaves an 88mm diameter disc for the inner chainring and the adapter spider to bolt to. So, again for the right arm the aluminum insert is made of one large piece of aluminum that is machined down to create the core insert with the adapter plate turned of the same billet piece.
From the outer side, a chainring spider slides down the arm, it has five tapped holes for the inner fixing bolts. The inner bolts pass through the inner chainring, a provided aluminum spacer, out to the front of the crank and seat into the spider.
The five bolts hold the inner chainring, and spider tightly to the aluminum adapter plate. Revolution cranks come with five machined from Ti 6Al-4V fixing bolts, that are 12.5mm long and have the industry standard 8mm by .75mm threads. Each of the bolts has a 5mm hex fitting for installation. Five machined 3.98mm thick spacers for the inner are provided. The spider is die- cut from 3.5mm thick aluminum plate, drilled for the fixing bolts then the inner holes are tapped. The spider plate is anodized Black.
We found the Revolution cranks to have a Bike-Pro Q measurement of 173mm. These cranks will work with any 2 degree tapered spindle bottom bracket. The mountain set uses the standard 74 and 110mm bolt pattern. Revolution cranks are made in 175mm length. The cranks come as right arm, left arm, spider, and the inner fixing bolt set. The Revolution arm set in a 175 length, with all included parts, weigh 460.5 grams. When ordering specify length.
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Syncros Compact Revolution