Wednesday, January 21, 2009

How to Disassemble a Racycle Crank (1896 through 1910)

The Racycle is one of those rare bicycles that warrants attention for its technical interest as well as its sleek looks. The principal technical feature of the Racycle is its unique bottom-bracket bearing and crank assembly. “The Racycle crank represents the only mechanically perfect crank construction that has ever been used on a bicycle….” So claimed the Miami Cycle Company in their 1908 Racycle catalog. Future posts will discuss what the perfection was all about, but here we are concerned with taking that mechanical perfection to bits to inspect or repair it.
Below are instructions directly from the Racycle catalog, in this case 1904, but the basic procedure appears to have been the same from 1896 through 1910. At the end of this post is a little bit about the thoroughly redesigned crank hanger that appears to have been first introduced in 1911.
Before you put this information to use, please read it at least twice and study the pictures, because the instructions are not entirely easy to follow, and there is the potential to get it very wrong and break an unobtainable piece: the connecting bolt. This square-headed bolt has a LEFT-HAND (reverse) thread, which means you have to turn it clockwise to loosen it. If you turn it counterclockwise like a conventional bolt (or if you know only digital clocks, so you are flipping a coin to see which way you’ll turn it), you are going to break the bolt. This will get the crank apart, but you’ll have to do some careful drilling and fabrication to get it back together.
Here are the manufacturer’s instructions, circa 1904:

“The machine should be turned upside down, so that it will rest on the handle bars and saddle. In dissecting the crank hanger, insert the pointed end of the crank bolt wrench (from the tool box) into the two holes in the cover nut on the right hand side and turn to the left, the nut being screwed in with a right-hand thread; this will loosen the cover nut. After taking out this nut remove the lock-nut on the opposite side, in the same manner; then place the socket end of the wrench on the bolt which holds the cranks together and turn to the right (not left). This separates the two cranks and they can be removed without taking the chain apart or interfering with the ball cups.
“On all Racycles both the lock and the cover nuts must be taken out before the improved connecting bolt can be removed. This connecting bolt has a left-hand thread, and must be turned to the right, otherwise the head of the bolt may be twisted off and would have to be drilled out.
“To remove the ball cups, loosen the clamp bolts on the lugs of the bottom bracket, and then unscrew the cups; this will expose the copper oil tube and the cone sleeve.”
Regarding the 1911 and later crank hanger, it appears that the connecting bolt was done away with in favor of an axle shaft to which the crank arms were attached in more or less the post-modern conventional way. I have very little information about this late-production revision except this page from a 1912 catalog.

Each crank arm appears to have been located to the crank axle with two short pins. Each crank arm is retained with a lock nut that had a conventional right-hand thread. In the center of the lock nut is a lock screw that the catalog says is LEFT-hand (backwards) thread. Thus, it’s still possible to tighten the parts that you want to loosen. Viva la difference!

The 1913 catalog does not describe any backwards threads. Indeed, from the 1913 illustrations, it appears that a spring lock washer was used under each lock screw, and perhaps this was done in order to finally abandon left-hand threads.

1 comment:

  1. You should check out the Raceface bottom brackets, they have the outer bearings and it adds at least an inch to the supported width of the bottom bracket spindle. They seem to be the modern version of the Racycle BB. They are a little weird to set up, but they are very light and stiff.

    They are the shizz! Perhaps Raceface should be spelled Rayceface?