The Strange Beast: 90's GT Tachyon

I first heard about the GT Tachyon through JimG's blog entry several years past. I have then since saw several came and went on eBay and the several internet cycling-related groups I am on. The idea of the Tachyon intrigued me--a stout trail bike built for a strange wheel size (but compatible to my favorite wheel size 650b) and has several distinctive features that's relatively cheap to get. I missed out on a San Diego area CL listing in January, even though a local contact was willing to facilitate the purchase. When another one surfaced in February, I found another contact in San Diego and grabbed the bike.


The sale included most of everything except the wheels on it. The seller had ditched the original 700D rims and rebuilt a pair of 650b wheels using the original suntour cassette hubs using Weinmann Zac19 rims. Since I already have a pair of 650b wheels (Velocity Synergy rims laced to a pair of Shimano hubs), I negotiated to buy everything but the wheels at a reduced price. I waited until my contact had some time to pack and ship the bike, and finally receive it several days ago.


I had planned to not use most, if not all of the original drivetrain, opting for parts compatibility/commonality in my bike garage. I took down the Suntour Command shifters, which were an innovative idea that places the shifting function close to the brake levers, akin to the modern integrated brifters that are now the norm. These shifters can operate in both index and friction mode, with the indexing only an option with Suntour rear derailleurs. I was able to take down most of the parts I didn't need (I planned on keeping and using the Suntour XC LTD front derailleur) except for the Sakae crank arm on the drive side. It was stuck, and the thread for crank-pulling was busted. This set up used a cup and cone bottom bracket; the spindle had a threaded section sticking out to be used with an M8 nut to secure the crank arm. My theory is that the additional length from the threaded section forces the crank puller to thread on less than sufficient number of threads, and perhaps some electrolysis between the Al crank arm and the steel spindle had taken place as well. I thought about and tried several methods, and at the end removed the crank arm and bottom bracket, still stuck together, by removing the fixed cup of the bottom bracket on the drive side. The build can now take place.


I kept the cockpit sans shifters, as well as the seatpost/saddle combo, and the front and rear brakes. The rear brake is a U-brake that's one of the unique feature of this bike. I am also pleased that the front cantilever brakes that come with the package is Dia Compe 986, which is one of my favorite cantilever brakes. Another unique feature that's staying on temporarily is the long flip-flop stem in matching color. I rather like the appearance of this stem together with the bike. However, given that the top tube is already pretty long for me (57.5cm), the long stem makes the fit uncomfortably stretched out with it. I will replace it with a VO stem adapter/threadless stem combo to bring the handlebar closer. The old headset is also replaced with a Ritchey Logic.


One other quirk that the Tachyon has is the sliding fork dropout that allows a rider to adjust the fork offset and therefore handling. It's a good concept, but the normally thoughtless action of popping the front wheel in the dropout requires some attention to make sure the wheel sits evenly between the fork legs. I have to ride with different wheel position to report whether it makes a noticeable different in handling.

After building the bike up to ridable conditions, I will probably add a Tubus Cargo rear rack, and eventually get fenders. I am curious about fatter tires, but the weight/cost/performance on different surfaces combination of Col de la Vie is quite good, and I am really hoping that Vee Rubber's 1.9" 650b tires Speedster and 12 will materialize. In any event, I hadn't had a chance to ride the bike extensively.

Here is the frame specs and current build list:


Tubing/Construction: GT Triple Triangle CrossOver geometry TIG Pulse welded
TANGE Infinity Double butted Chromoly tubing
Frame: GT Triple Triangle Chromoly Cross Over frame
Fork: GT Chromoly Unicrown w/2x4 with multiple position dropouts
Headset: 1" Ritchey Logic threaded headset
Stem: GT Chromoly/Alloy Flip Flop
Handlebar: SR Modolo Anatomic Bend aluminum
Brake Levers: Dia Compe Aero BRS w/black hoods
Brakes: Frontt-Dia Compe 986 Cantilever black; Rear-Dia Compe AD990 U-brake
Shifters: Shimano S-A400 downtube friction shifters
Crank: Suntour XC-LTD 175mm crankset; 46/34/24T rings
Bottom Bracket: Shimano UN54 68x127mm
Front Derailleur: Suntour XC LTD triple; 28.6mm
Rear Derailleur: Shimano Black LX long cage rear derailleur
Cassette: Shimano 8-speed cassette 11-30T
Hubs: Shimano Tiagra rear hub 130mm OLD and Shimano XT front hub
Rims: Velocity Synergy 32-hole rims
Tires: Panaracer Col de la Vie tires
Seat Post: GT/True Temper Chromoly w.alloy micro adjust
Saddle: GT ATB Super Soft Gel foam
Pedals: Mavic performance road quill pedals

Santa Rosa Saunter East to West

I have now signed up officially for the SFR Nor Cal Fleche, which is a team randonneuring event that goes for 24 hours and minimum 360km (or 224 miles). I have done the Point Reyes Lighthouse and Valley Ford 200k's, and was planning on riding the Russian River 300k, but a scheduling conflict arose in the days leading up to the ride and I felt a need to find a replacement as a stepping stone to the Fleche.

I looked for permanents--routes approved by RUSA (Randonneurs USA), that when ridden following randonneuring procedures, give riders credit in some situations just as an organized brevet events--from San Francisco Randonneurs, Santa Rosa Cycling Club, and the Davis Cycling Club. I found a route that's fairly similar to the first part of the Fleche route my teammates and I designed. I contacted the permanent owner, and set up to ride toward the end of the week.

The Santa Rosa Saunter (SRS) can be ridden in both the east-west or the west-east directions. My grand ambition is to start in Davis and complete the 202k (126 miles) permanent in Santa Rosa, then continues southward for as long as I can to add miles. I would finish at a bigger town to catch a bus back to San Francisco or the East Bay. I picked the SRS because it is relatively flat--only one major climb is in the cards, and the rest are gentle rollers. I took AMTRAK to Davis the night before for a 5:30AM start the next morning.


It was still very early in the spring, and the temperature, especially in the central valley still got down to the low 40's in mornings and nights. I had on a long-sleeve base layer, a thick long-sleeve jersey, a warm vest and a windbreaker for the top, and a pair of cycling knickers and leg warmers for the bottom. After getting an ATM receipt at the start in Davis, I began rolling eastward on what would become route 31. It was dark still, but getting brighter as we were a day away from switching to daylight saving time. The first 25 or so miles are basically flat with an ever so gentle incline to ~ 450 ft. Route 31, then route 93 takes one through flat farmlands and orchards around Davis, Dixon, and into Winters. We have had wonderful fruit blossoms this year due to the cold weather, and the lack of precipitations meant that they get to stay on the trees a little longer. All long the first part of this course blossoms of different variety lined or dotted the roads.


The route turns south just west of Winters onto HWY 128 W, which I would be getting off and on again later in the day. At the junction of Grand Ave and HWY 128 W outside Winters, I saw a flock of big birds trying to cross the street, yet they were turkeys. About a dozen peacocks of both genders were trying to determine my intention and keeping their distances. I am familiar with peacocks, as the campus on which I went to high school and now work to set up two new college programs have lots of them roaming freely. These birds were wild. I told my wife later about them and she joked maybe some of them ran away from my campus (in Ukiah more than 100 miles away) and settled down here.


The road turned up slightly after the intersection, but flattens into a true gentle downward roller toward Fairfield. This stretch on Pleasant Valley Road (also HWY 128) was aptly named--the combination of the crisp morning air and rising sun, the even and smooth pavements, and the tall and rugged old oak trees and the multitudes of birds make this a cyclist's dream road. I was going at a good pace, and soon I got to Fairfield. Even though it wasn't a control, I stopped to buy some energy bars at the local Safeway before rolling onto Rockville.


At Rockville, I stopped at the Valley Cafe to get my official receipt for the control. This is a nice establishment, kind of an old-fashioned breakfast diner where folks sit around the counter and chat before going off to work. I bought some food, refilled my bottle and got going again. Now I was heading north on Suisan Valley Road, which later turned into Wooden Valley Road. This stretch was another highlight for this ride. Though I was beginning to be a little alarmed by the north-to-south headwind that was beginning to pick up, I thought to myself that the wind conditions in Napa Valley, which is beyond a pass from where I was, and where I would ride for close to 40 miles toward the north, might be different. Plus, it's mostly flat anyway. I wasn't going fast as I approached the intersection of Wooden Valley and HWY 121, but I wasn't hurting, and climbed up to Mt George with plenty of gas in my tank. The climb was gentle and well-paved, and features sweeping views of the valley below. At the top, I ate some food and hung on for the fast descent, which had several fast and sharp corners. Soon I was in Napa Valley.


When I turned onto Silverado Trail, I had a full bottle of water. Even though I knew going beyond the first 5 miles on the trail I won't be able to find any service option, I thought I could get to Calistoga with a bottle, especially since the terrain is supposed to be "flat". So I bypass the deli/market that came up shortly, and continued on the trail. It was near mid-day, and the warmth and the strong headwind somehow made me more thirsty than usual. I was also battling sleepiness for some reason. Even on this "flat" section (which I later found out to be an up-trending roller) I wasn't able to maintain a good speed. Finally, in St Helena I decided to take a short detour to town to get some fluid at a gas station. St Helena on a sunny friday afternoon was super busy and hard to navigate as a cyclist among all the impatient cars stuck in traffic. I got back on route and was glad to be out of the chaos. I felt better after water and an energy drink. I ate some and got to Calistoga at a modest pace.


At this point, I decided that I would quit in Santa Rosa and take the bus home, so I felt more relaxed. I filled up my bottles again, and bought a bottle of coconut water to drink with an energy bar. I took a moment to gather myself and began the last stretch of 35 or so miles to Santa Rosa. Besides a small incline just outside of town, the rest of the terrain was flat or down-trending roller. Trees lined the first portion of the road toward Alexander Valley and besides being scenic, it was also very fragrant. Later I rode through a section of roads with large blossom trees on both sides. On flat sections I can see beyond the vineyard HWY 101 to the west. Soon, the road curves to the left and turned into Alexander Valley Road. The food, water, and rest in Calistoga finally began to kick in and I felt a second wind and picked up my pace again.


From Healdsburg Ave going south, I literally picked up a wind, as the headwind I was battling for nearly 40 miles in Napa Valley now was a tailwind behind my back. I stopped in Healdsburg to buy a sandwich and get my control receipt, then headed to Santa Rosa on Old Redwood HWY. The tailwind and the slightly downward gradient made for a fast trip to Santa Rosa and the last control. I had to get in and out quickly as I had to catch the bus to San Rafael for another bus back to the East Bay.

I actually felt pretty good at this point, and could have probably ridden to San Rafael, but I did need to get back at a decent hour. I haven't had to battle sleepiness on a brevet before so I need to watch out for it. Was it because of the shortage of fluid? Maybe I need to eat more? My legs were fine, but the sleepiness  in Napa Valley took the motivation from me to assert my power, in fact, my heart rate was low (115 -125) even when I was experiencing a lack of power--I was certainly not over-working!

The specialized sequoia, with 650b wheels, low-trail fork, and cantilever brakes worked fantastically on the ride. I use panaracers CdlV and though they are not as plush and free-rolling as the Grand Bois Hetres or even Soma b-line, they rolled well enough and are plush enough that I felt comfortable and unencumbered on the ride. The Tektro CR720 brakes are powerful, modulate well, and are pretty quiet. The Sequoia, built with relatively lightweight tubes, respond very well to my pedaling strokes. I can sync with it well on and off the saddle. Even though giving up my Stag pre-order spot was difficult, as on paper it's quite a nice bike, I think the Sequoia performs just fine for my purposes. I enjoyed a great early-spring solo ride through much of the Northern California wine country, and may now be ready for the fleche