Sunday, December 7, 2008

All forked up - Part 1

Headset cup press...piece of cake! Time for forking! :>)

I had a fluid leakage issue with my 'new' fork. I'm hoping I've resolved that particular problem and I'm going ahead with the installation. I'll just have to keep an eye on it.

First order of business: cut the steering tube to length. Luckily, the folks at Cane Creek provided some excellent instructions on how to measure the various components and calculate the proper steering tube length. The formula is:

Lower cup height + Upper cup height + stem height + head tube length + headset spacer height - 3mm = steerer tube length

The best way to measure these items? This tool has become one of the most indispensable items in my burgeoning pile of mostly working bike tools:

6" Mitutoyo Digital Calipers. Don't leave home without them.

Bearing cup height measures the flange containing the bearing only, not the part of the cup that presses into the head tube. My lower cup height is 10.9 mm, and the upper cup height is 16.5mm. I'm using 3 spacers to bring my bars up a bit, total height 25.3 mm. Add in my stem height (the height of the stem clamp, fits on the steering tube)...40.0mm, and a head tube length of 110.2mm and the total is 202.9mm. Let's round that up a tenth to make it an even 203. Subtract 3mm and the steerer tube length is a nice round figure of 200mm.

However, before I started chopping at my steerer tube willy nilly I wanted to make sure my arithmetic was correct. The tried-and-true maxim of "measure twice, cut once" certainly applies here! So, after I measured the steerer tube and scribed a line at exactly 200mm, I prefit all the parts as a precaution. The top of the steering tube should be 3mm below the top of the stem clamp, or the headset top cap.

As you can see in the picture below, the steering tube extends past the stem clamp before cutting. I don't see my scribe line at 200mm...this is a good thing. That means it lies somewhere below covered by the stem clamp.

I used a pencil to mark the steering tube circumference at the point where it meets the stem clamp, then I disassembled everything to check my work.

A bit fuzzy here, but you should be able to see my pencil line around the circumference of the steering tube, and the short scribe line directly below. Measuring the distance with my trusty digital calipers, I get an approximate distance of 4mm. I haven't yet installed the crown race on my fork (I probably should have done that first before I preassembled the parts), but I don't think that will add much more distance so I believe my measurements are accurate and correct.

Next: cutting the steerer tube to length.


No comments: