I got a new bike. I certainly didn’t expect to get a new bike but my friend Spike gave me a frameset. But not just any old frameset, but a shiny chrome Bianchi SASS; SASS is Bianchinese for Shiny Ass Single Speed. Now if the truth be known, I really didn’t need another bike, but I was on the look out for a SASS, Why? Well, umm, er, you see...hey, it's a Shiney Ass Single Speed, that's why! And the 
idea came to me; a fixed gear mountain bike. Yes! I have heard stories about these, but never seen one in person. If singlespeed is the equivalent of climbing Mount Everest, fixed gear is like doing it without extra oxygen. 
The most logical build would be a fixed/freewheel fliop/flop rear hub. They only catch is a SASS is made disc specific and you can’t have a flip/flop hub with a disc brake since you only have one caliper. The answer was simple, a cheapo side pull brake would do the job. For components have a Planet X chrome BMX crankset that I bought in parts for no particular reason. I also have some Ritchey handlebars, stem and seatpost and Shimano brake levers, so all I need (besides wheels) are the brake calipers and a seat. I decided on a Avid BB-7 w/ 185mm rotor, a generic, but long throw canti-brake and a THE seat, on sale and looking a lot like a old style Bonty seat ; the total price, less than $80.
Now about the wheels. Finances as they are, I do not have the funds to buy/buid a new wheelset; I’m thinking 650B. I do have a rear wheel off my rigid SS bike, with a flip/flop free/free, non-disc hub/rim; that will work for the rear. I also have a front disc wheel off another bike, they only difference being the caliber is setup for 180 rotor, rather then the Avid 185, but I figured it would work okay and I figured right. As I said before, I wanted to have the option to run this bike as a fixed gear. Now, track cog with thread onto a hub made for a BMX freewheel, but there are no reverse threads to lock it down. A work around 
involves using an old loose ball bottom bracket lockring. These rings thread the same direction of the track cog, so you cannot completely rely on them to hold the cog under reverse torque. But, they are an added precaution and with the aid of some locktite, (which I did not use), it came be a reliable fix; but a bugger to remove. Since I will have a rear brake, I will not rely exclusively on rear torque to stop/slow the bike, so I figured the locktite was not necessary.So, I put it all together and headed out to Soquel Demonstration Forest in Santa Cruz to try out this fixie mountain bike thing. Today was the day. Spike showed up in his van with his new Sette 29er dingle speed and I had my SASS fixie. In case you didn’t see it, here’s another pic; I added the rear brake and lever. SASS frames are disc only, but my plan was for a fixed/free, so a disc would not work. The plan was a Demo Forest ride (Santa Cruz, CA). The ride is about 13 miles, starts with 1000 foot climb on apaved and fire road, 2000 foot downhill singletrack (we road Tractor), and 1000 foot climb back out to the lower trail head; difficulty is somewhere between medium/expert to expert. The first climb was not much different than usual, perhaps a little easier because of the fixed gear. In the middle of the climb there is a single track, which gave me my first real taste of off road fixed gear riding; very awkward at first. When setting up for an obstacle, once tendency, especially on a flat or down hill, is to stand up and momentaarily coast; this of course is not possible on a fixie. I have read the technique is to lock up the rear wheel just before the obstacle. My first inclination was to just go for broke and hope I wouldn’t catch a pedal; this worked exactly 5 times. Number six didn’t result in a fall, but convince me I needed to start working on locking the rear wheel; the technique is easier than you would think, especially with a rear brake. After 3-4 tries, I found when the release point was and after that I started actually looking forward to the numerous log crossing on the trail.
There were also a number of ruddy downhills. I first tried to stay seated, but that was too painful and unsteady. The trick is to standup, brake and pedal at the same time; again something that takes some practice, but is picked up fairly quickly. By this time we were at the top entrance to Demo Forest and the Ridge Trail. It’s pretty much downhill after this and my original plan was to switch to a freewheel at this point, but I decided to continue on with the fixed gear. Using my newly acquired skills I continued on and found I was able to negotiate increasingly more difficult terrain. On my mind however, was a small patch of downhill baby heads after the helipad. Again I had planned to switch to freewheel before the baby heads, especially since I had crashed the last 2 times I had ridden them. But, again I had already negotiated the trail to this point, so I again decided to continue. The baby head section is very rutted, so you really have to pick your way through without the front wheel washing out. I took the section to the right, which is less rutted, by requires a quick right at the bottom. I put my mind in “I’m going for it” mode and before I knew it, the front wheel dropped down at the bottom and to my surprise I made the turn and rode to the second section. This section is longer but not as steep and I made it through feeling very good about myself (especially since Spike took a minor spill in the first section). We finally reached the trail head to Tractor. Of the 5 main trails at Demo Forest, Tractor slightly less technical than Braille or Sawpit, but has a number of long sweeping turns and can be ridden a very high speeds. I picked it because if I did fall, I would do less damage to myself then the other two, which have some very steep downhills and no safe place to land if you fall. The ride was a hoot and I actually found myself wishing it was more technical (next time). Once I got to the bottom I was pretty much done, but it was a great ride. I expected my legs would be toasted, but it was my upper body that was feeling worse for ware. I pretty much crawled back to the lower trail head (a 1000 foot climb out). I was left with the realization that a fixed mountain bike is very rideable (if I can do it anyone can) even over technical terrain. It was a HOOT and it’s something I want to do again!
