Wednesday, August 12, 2009

Speed Wobble

I mentioned that I made 3 rides out of the 10 I planned on vacation. The second ride I ended up riding on Rt 3, South-East of the 30/3 split, following this route:

Rt 3 is very hilly compared to Rt 30 that I had ridden the day before. Given the fact that I am out of shape and a lot heavier than I had been last time I was riding this area. Because of this I do not like to just drop down hills and I end up braking most of the way down the hill. In order to be safe about the braking I alternate between the front and rear brakes so that neither of the rims will heat up to much for a blowout.

While I was braking I realized that I was not slowing myself down enough to be at my comfort level. At this point I started hitting the brakes a little harder. On a particularly steep part of the hill I noticed a strange vibration in my bike. This vibration felt a lot different than I was used to. I decided to look down and realized that my front wheel was vibrating very hard on the outer part of the rim.

This scared me. Really, really badly.

Not only did I think I was going to fall, I was worried about how I would fall. If I fell I would either have the choice of falling into Rt 3 or the other direction into a wire barricade that would keep me from falling down a very steep hill side.

Rt 3 at this point has a 55 mph speed limit and is highly traveled. Almost certain that I was going over, I unclipped and got ready to go down. Fortunately at the last second the vibration stopped. I was able to regain control of my bike. It took me a long time to stop shaking from this event. I came to a complete stop to regain my composure.

I was initially going to stop at a junction called Indian Pass however I decided to going down a road called Corey's and take some time on a slower road with very little traffic.

I couldn't stop thinking about what could have happened to me. I had just bought a new wheel set from a friend of mine. The friend is an excellent mechanic, so I had no reason to doubt the wheels. They were true and stiff with deep rims. Even knowing this, I felt as though something just wasn't right with them. When I got back and checked them and I noticed some side to side play in the hub.

I decided to take the wheel set to Placid Planet Bicycles just to be safe. When I got there I showed on of the mechanics the wheels. The mechanic told me the wheels to said that there was a little in the hub, but it wasn't enough to worry about. He said that he would tighten them up and I took him up on it.

After he was done I told him what had happen on that descent. He told me that it was a phenomena called speed wobble. Then he told me what causes it and how to fix it. What I found particularly interesting is that he even knew my bike (just by me telling him the model) and told me that it was more common because of how the rear triangle had a dropout where the wheel connected to the frame.

After I got back, I put the wheels back on my bike and took it for a ride. The wheel set felt very tight and just how I was used to it. I also made the adjustments to the brakes like the mechanic suggested and the next time I rode, I was much more confident in my bike.

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