Precision Tooling is a family owned machine business that has machined parts from metal for different companies over time. For a period they were the sub-contracting firm making CQP cranks. The relationship with CQP faded and John Trenerry and his father Phil worked out an exciting and stylish design for a crank arm set. Phil's knowledge of metals helped make the arms strong though they appeared delicate. There was initial un-certainty about whether the family should be bold enough to enter the bicycle parts market on their own, under their own name. As it turns out Phil Trenerry had known John Grafton for many years and Grafton's first cantilever brake had been successful. Grafton had been prevailed by others make an entrance in the crank market and the Trenerry's crank held promise though they again were reluctant. The Trenerrys agreed to make the crank they had designed and let Grafton market them. The crankset's popularity and the Grafton name identification lead to immediate market interest. After about a years time we started to be sold the cranks directly from Topline, (which is also known as Precision Tooling), because their verbal contract with Grafton had crumbled. The design remained rightly in the Trenerry hands and they have become very successful using their own name in marketing their own cranks. We've found that generally when splits like this occur, there is usually a problem related to sub- contractors being paid for their work. Have you noticed how similar the Sims cranks are to the last version of Grafton cranks? It's not a well kept secret that Sims was the sub-contractor used to make Grafton cranks after Precision Tooling (Topline)/Grafton relationship ended.
Precision Tooling first crank under the Topline name was this Mountain crankset. The arm set is made of strong, lightweight 7075-T6 aluminum, elegantly machined in simple shapes with fine finish work. The arms are turned on a lathe from aluminum billet to create the shape of a ball at each end, joined by the slender, tapered arm. The back of the large, 35.5mm diameter ball of each arm is milled to make the arm offset, as is the pedal boss face and the crank arm bolt area. One of the differences in these arms over other American makers is that the back of the pedal boss isn't milled away. Top Line retains the 24mm diameter ball shape at the pedal, drills and taps the pedal threads, leaving the back of the pedal spindle enclosed in the arm. There is a certain elegance to it. The bottom bracket spindle hole is drilled, then the sides are tapered by fine numeric milling. The crank arm bolt recess is drilled and cleanly tapped with 22mm by 1mm threads for the arm dust cap. The top and bottom of each arm have an expanding groove milled into them. This reduces weight without compromising the integrity of the arm. To accommodate wider cage front derailleurs, and reduce weight, the back of each arm is milled in a flat, smoothly curved radius. Each of the arms is given a high polish and then anodized. The spider is made of machined 1/4" (.250") aluminum plate. It is cut to shape, milled on the top and bottom of the arms for the chainrings, drilled and tapped for the fixing bolts. Then it is high polished and anodized in a color to match the crank arms. The spider threads onto the back of the large ball and a stainless steel pin is driven into it from the rear to secure it rigidly and permanently in proper place. This crankset is compatible with all 2 degree tapered bottom brackets, and uses the standard 74mm and 110mm bolt pattern. The cranks come anodized in Black, Blue, Pewter Grey, Lavender, Silver, or High Polished un-anodized silver. We stock them in 170mm, 172.5mm, 175mm, 177.5mm, or 180mm lengths. On a special order basis we can order the cranks anodized in Gold, Green or Red, and we can also special order any of the colors mentioned in a 165mm or 167.5mm length if needed. The Topline Mountain cranks had a Bike-Pro Q measurement of 156mm. Top Line Mountain 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 and crank arm dust caps will be needed separately. We found the 172.5mm arm set, with spider, bolts and spacers, in Black weighs 445 grams. The 180mm length in Lavender, with spacers and bolts weighs 473.5 grams. The inner bolt and spacer set provided weighs 33.5 grams. Be sure to specify length.
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Topline makes a variation of their Mountain cranks with the spider milled out around the 35.5mm large ball. Remember the back side of the spider on the standard ATB drive arm (called "Heavy Duty" by Topline) is already milled to reduce the spider thickness from 6.297mm to 4.480mm, the SLS model has the mill work performed on the front side and in this case, cuts the material away altogether. The weight of a 180mm standard (Heavy Duty) right arm is 246.6 grams, while the weight of the an SLS version of the 180mm arm is 214 grams. These cranks again use the 74mm and 110mm bolt pattern. The cranks come anodized in Black, Blue, Pewter Grey, Lavender, Silver, or High Polished un- anodized silver. We stock them in 170mm, 172.5mm, 175mm, 177.5mm, or 180mm lengths. On a special order basis we can order the cranks anodized in Gold, Green or Red, and we can also special order any of the colors mentioned in a 165mm or 167.5mm length if needed. We found the SLS cranks had a Bike- Pro Q measurement of 149mm. The Topline SLS cranks have a Bike- Pro Q measurement of 149mm. Top Line SLS Mountain 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 arm bolts, and crank arm dust caps will be needed separately. The weight of the 175mm long SLS crankset with spacer and bolts is 388 grams. The inner bolt and spacer set provided weighs 33.5 grams.
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A Micro Drive compatible drive arm is an important variation to keep in a crank stable. In 1991, when Suntour cleverly introduced the first Micro crank, immediately the importance of reduced diameter chainrings with the reduced weight and chainstay clearance became obvious. As the concept caught on, more crank makers began to make cranks with spiders drilled for a 56 bolt center diameter inner chainring, and a 94mm BCD middle and outer chainring. Topline was either the second or third maker after Suntour to introduce a crank set with a 56mm/94mm drive arm. The left arm of this set is identical to the two described above. The spider is different from the drive arm used above on just the right arm. Machined from 6.29mm thick aluminum plate, the back side is milled away where possible to reduce the spider weight further. The cranks come anodized in Black, Blue, Pewter Grey, Lavender, Silver, or High Polished un-anodized silver. We stock them in 170mm, 172.5mm, 175mm, 177.5mm, or 180mm lengths. On a special order basis we can order the cranks anodized in Gold, Green or Red, and we can also special order any of the colors mentioned in a 165mm or 167.5mm length if needed. The Topline Micro D arms have a Bike-Pro Q measurement of 151mm. Topline Micro Drive compatible 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 and crank arm dust caps will be needed separately. The weight of the 175mm long Topline Micro Drive crank arm set with spacer and bolts is 389 grams.
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For the 1994 model year, Shimano went out on an intellectual limb and introduced their version of a micro crank, they chose not to use the 56mm/94mm pattern that Suntour had pioneered three years earlier. The Hyper Drive-C crankset, as Shimano calls it, uses a 58mm bolt center diameter for the inner chainring and 94mm for the outer chainring. Topline's makes a Hyper-C compatible crank arm set by drilling the inner holes outward on the spider arm (1mm is all that's needed). Because of the same change in drilling there is no weight difference between this arm set and the Micro D model. The cranks come anodized in Black, Blue, Pewter Grey, Lavender, Silver, or High Polished un- anodized silver. We stock them in 170mm, 172.5mm, 175mm, 177.5mm, or 180mm lengths. On a special order basis we can order the cranks anodized in Gold, Green or Red, and we can also special order any of the colors mentioned in a 165mm or 167.5mm length if needed. Topline Hyper-C cranks come as right arm, with spider, left arm and a set of five steel inner chainring bolts with aluminum spacers. We found them to have a Bike-Pro Q measurement of 151mm. Chainrings, the double chainring bolt set and crank arm dust caps will be needed separately. The weight of the 175mm long Topline Hyper Drive-C crank arm set with spacer and bolts is 389 grams.
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Top Line also produces a road bike version of their crank arm set. They are made nearly the same as their famous mountain bike cranks. Each of the arms is turned on a lathe making the smooth and rounded shape. The backside of the arms, like the Mountain arms, is milled away slightly. This is so the right arm doesn't interfere with the front derailleur. The top and bottom of each arm is milled with a groove that gradually widens as it moves from the pedal toward the bottom bracket. These grooves reduce the weight of the crankset. The spider is machined from 6.32mm thick aluminum plate. The primary difference in these cranks, naturally, is the spider. On the road version, because there is no inner chainring, each of the spider arms has the center milled away from the top. The road cranks have same pedal fitting, where the pedal ball is drilled and threaded without piercing through the backside of the arm. These are elegantly fashioned while loosing none of their utility, and will give any bike a functional, one-off appearance. Topline Road cranks use the 130mm chainring bolt pattern and do not come with chainrings, chainring fixing bolts or crank arm dust caps (Sims or Cooks are recommended). These you will need separately. The Road arms are made only in Black or High Polished Silver and come in 170mm, 172.5mm, 175mm, 177.5mm, or 180mm lengths. We found the Road arms to have a Bike-Pro Q measurement of 150mm. The 170mm arm set, with spider in Silver weighs just 363 grams, the 172.5 set weighs 369 grams. Please be certain to specify length.
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