Headset experiments

by Brian Mullin on April 14, 2007

Following my trails and tribulations on my never ending diet to be a weight weenie I decided to try running my bike without the headset cap and bolt. Theoretically you only need to tighten down the headset cap initially while you preload the bearings in the headset and once the stem is tightened down it holds the load on the headset bearings, so the headset cap and starnut are no longer needed.

So I removed the headset cap and bolt and got rid of the starnut. Now getting rid of the starnut was easier said then done. You can push it all the way through the steerer tube but I didn’t want to scratch up the inside and I wasn’t sure if I had a decent tool to push the starnut the entire why down the steerer tube. So I got out my handy dremel and slowly cut off a couple of the starnuts wings. This was a very difficult job since the dremel cutter was pretty close to the same size as the width of the steerer tubes diameter. Felt a bit like a Doctor working on a patient.

I made a few mistakes and hit the walls of the steerer tube, but it was nothing drastic (there goes the patient, vital signs off the chart). After I got the first layer done and broke it off I had to move to the second layer of the startnut. This was a bit more of a pain since it was down a bit deeper into the steerer tube. But I was much to deep into the project now and darn if I wasn’t going to complete it. Finally it was done and no more startnut.

So by dropping the headset cap, Aluminum bolt and the starnut I saved about 20.3 grams.

No its time to test the setup. So I went out for a bike ride on my full suspension Ibis Mojo and everything seemed fine. I was doing my normal rocky trails and the system seemed to be just perfect. I next went up into my rock gardens and started to play. Thats when I noticed that the stem had moved up maybe 1/16 of inch. The headset bearings were no longer loaded properly. Ugh, danger Will Robertson! Now there was no movement in the headset and steerer tube but I certainly was apprehensive. I rode through so more rock gardens and such and it did not seem to move much more, but I was also taking a bit of a lighter approach to things.

So I did not have any confidence in running my bike through tough rock gardens that I frequent without the headset cap system in place. Now I might have been able to crank down the stems bolts, but I just decided that this was the wrong approach to save some weight. I also have titanium bolts on my stem and I don’t want to torque them down too much. Of course I could also switch to steel bolts instead of the titanium to increase the ability to crank down the bolts, but again the interface strength that having the headset cap gave to the headset system was just to important for me to play with.

Now I needed to figure out what to replace the startnut with. I could go back to a startnut again but I wanted to have something thats removable. I looked at a couple of alternatives. The first one was the Extralite Ultarstar. Now it looked pretty cool and they have a great reputation. It weighed 8 grams but it was $34 (ouch).

The second one I looked at was the Tune Gum Gum. It weighed 9 grams and was only $18. Lets put that in perspective of a startnut which weighs between 10-15 grams but only cost $2-$5. I bought the Tune Gum Gum since it was cheaper.

I got it in the mail and it didn’t seem like much. Just a small rubber plug with 2 metal washers and another rubber piece. One metal washer has a set of threads and it plugs into the bottom of the rubber plug. I put the headset bolt through the headset cap and threaded it onto the Gum Gum and tightened it down until the everything was loaded slightly. I then put the system in the steerer tube and tightened down the headset. I loosened the stem bolts and then I tightened down the headset bolt using the usual method for loading the headset bearings. I then tightened the stem bolts and everything was back to normal. I was then able to loosen the headset bolt and pop off the system. It was easy to take the entire system on and off completely.

If you had fragile carbon steerer tube this would be great product since it doesn’t have anything that could harm the carbon tube.

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