Mostly recaps of two wheeled rambles through the countryside, but sometimes thoughts on other things.

Tuesday, February 24, 2009

Bike Build Notes

[Advisory: If you don't find bikes interesting, this post may lull you to sleep. read or don't depending on your need for rest]

The blue frame set of "Winter Bike Project" renown is my 1st attempt at a full up bike build. The fact that I live about 2 miles from a capable bike shop emboldens me to go where this man has not gone before. I hope the mission does not take the 5 years that James T. Kirk spoke of. There will be much trial and error, consulting of manuals and mounting and re mounting parts on the way to getting them right. One of the first things that raised some eyebrows on the 650B forum was using a Velo-Orange bottom bracket with a Campagnolo Veloce triple crankset. V-O uses a Shimano style tapered shaft and some wondered if the two would work together.

From the Branford Bike files:

>>>>Compatibility - length and tapers

All cranks must be matched with a specific length bottom bracket spindle. Triple cranks or frames with oversize seat tubes require slightly longer bottom bracket spindles. Shimano and almost every major bottom bracket maker have traditionally used the same spindle end cross section of 12.9 mm and two degree taper. Campagnolo uses the same two degree taper but has a smaller starting cross section of 12.7 mm. A Shimano crank arm will bottom out on Campagnolo spindle. A Campagnolo crank arm will not draw far enough onto a Shimano spindle. <<<<<

As it happens, the distance from the center of the seat tube to the middle ring of the crankset needs to be 47.5 mm for this set up. I was able to get it to 48 mm, and decided it was good enough. After mounting the derailer and manually operating it, there seemed to be the right amount of range for proper chain movement. If it doesn't work out with a chain attached, I can always replace the BB with a correct Campy one.

Sheldon Brown wrote:

>>>>In practice, you can very often get away with mixing these sizes, as long as you select a spindle length that gives the desired chainline.

Taper matching was fairly important back in the day of loose-ball cup-and-cone bottom brackets, because these required regular maintenance/overhauls, and this required removal of the cranks. Every time you remove and re-install a square taper crank, the hole in the crank is liable to get very slightly larger.

This was particularly an issue when using J.I.S. cranks on ISO spindles, because over time, as the crank went on farther and farther, you could run out of taper, and the square end of the spindle would become flush with the surface the crank fixing bolt/washer pushed against. At that point, further tightening of the bolt won't make the crank any tighter, since the bolt is bumping onto the end of the spindle.

These days, however, most folks are using sealed c

artridge bearing bottom brackets. With these, there is no routine maintenance required, so typically the crank will be installed once, and will stay in place unless/until the bottom bracket needs to be replaced. This greatly reduces problems of wear to the interface.

I generally avoid mixing sizes on customers' bikes, but I have a lot of experience mixing ISO/J.I.S. in both directions on my own personal bikes, and it has never given me a lick of trouble. <<<<<

I should add that my Campy Veloce double on the Mark III is running quite nicely on a Tange BB.

The tracking page at UPS says the next delivery is still on schedule for tomorrow, but I won't be surprised if that doesn't happen. It was in Kansas this morning. Maybe if the driver clicks his heels together 3 times.... "There's no place like home.."

Note: The ruby slippers still work their magic, for the box was here when I came home from work today. Here's a picture with a few additions. Can you spot them all?

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