Sunday, September 30, 2007
How high to go?
This is my current set up. The stem is above the head set using 4 spacers of 20 mm each. Now add the stem and the leverage on the steer tube is a cause of concern that the force will cause a break. Currently the spacers move around some as I ride, making noise.
I started on my quest for the answer by talking to Josh Coaplen Director, Research and Development for Cane Creek Components. He suggested using the part of a Cane Creek head set that holds the steer tube tight against the head set bearing. This is a tapered split ring. (compression ring) Other head set makers like Chris King do not take advantage of this feature. The benefit is a tight interface between the top bearing and the steer tube. I was already using an S2 with this feature and am glad because it works very well.
Next we discussed the slight but perceptible amount of flex in the steer tube and the effect it has on the 4 head set spacers stacked on top of each other before the stem.
We discussed how interlocking spacers would help and perhaps 4 interlocking aluminum spacers would also add structural integrity. Adding 4 interlocking spacers will be my next task when they arrive from Cane Creek.
Then we agreed that the issue is really one for the fork manufacturer. I am running a Kinesis Max Light After a lot of internet searching I was able to find two for my ERB bikes.
I tracked down the engineer of Kinesis at Interbike and he told me the fork I am using is about 3-4 your old model they no longer make. Because it is aluminum it should be run at less than 80 mm from the head set. If using a chro mo fork/steerer then 100 mm should be the max hight. Aluminum would crack or sheer all at once causing a catastrophic failure when steel (chro mo) would bend first before breaking.
On the plane ride home Martin Stenger (engineer for Bob Trailers
and NORBA Pro #10 1990) and I talked about the physics involved.
This set up by VooDoo bikes is a great way of solving the problem:
So when the new Cane Creek interlocking spacers arrive I will put them on and cut down the seer tube to get it under 80 mm.