# 1991 GT Tachyon - Monstercross Candidate



## N10S (Sep 27, 2004)

I won this back in January from a guy in Switzerland, and finally received it a couple of days ago. Really in pretty nice shape overall. A few scratches and scuffs here and there, but otherwise very straight with no dings or dents. Its equipped with almost all of the original equipment, with the exception of the rear derailleur which is a Shimano RC\STX instead of the original XC ltd. All of the bearings are smooth, and the bike seems like it led a pretty sheltered life. Even the 700D road tires are in decent shape with no signs of cracking. As you can see in the following pic the guy had the command shifters mounted on top of the bars which was a big selling point for me. Everything in the first picture is assembled as received. 








I did not originally buy this to leave it stock, but since it is in nice original condition I may end up going that route anyway. Not like its a highly desirable rare vintage bike, but you don't see many of these floating around these days either. The following pictures reflect a few quick changes including a set of Midge bars with the accushift command shifters re-mounted in the proper position, and a new Wtb ti railed leather saddle.


















My original vision was a spartan 1x geared GT Tachyon Monstercross\off-road drop bar build using Pacenti Neo-moto 2.1 knobby tires on the stock rims, or maybe even possibly build up a lighter 650B wheelset for off-road use. The other boat anchor parts like the BB, seatpost, and crankset would also need to be boxed and upgraded (most of which I already have) for lighter weight kit. Seems like the bike is begging for a flite saddle too.

Always interested in others feedback.

-Jeff


----------



## yo-Nate-y (Mar 5, 2009)

Nice bike. Personally, I'd be tempted to use it for a commuter.


----------



## N10S (Sep 27, 2004)

I wish I had decent roads and was close enough to work to bike commute. As it is I would be facing around 35 miles of heavily traveled narrow B highways with no shoulders, deep ditches, and blind corners. Pretty much a cycling accident waiting to happen. It is a neat frame with lots of braze-ons for racks though, so your suggestion would be a good one for the right person in the right location.


----------



## Sizzler (Sep 24, 2009)

Pretty slick, I like how it looks! Any future upgrades in mind?


----------



## IF52 (Jan 10, 2004)

I'd do the 650b bit. Maybe Quasimotos instead of Neos. Look on the 650b, 69er and new wheel trends forum, there are a few Tachyons rolling 650b over there.


----------



## N10S (Sep 27, 2004)

Sizzler said:


> Pretty slick, I like how it looks! Any future upgrades in mind?


I was envisioning the following:
-ti square taper bb
-race face lp cranks with single 32 t ring
-Paul chain keeper 
-aluminum or ti seatpost
-flite saddle
-remove fd and front shifter
-knobbies
-maybe a lighter set of wheels and hubs
If I keep the stock wheelset then I will keep the suntour 7spd.If I build a new wheelset then I would go with a shimano cassette and single bar-end shifter. 
Thats the basic direction, and that set-up would allow me to hit most of the local single track and still be ok for gravel grinding and limited road use.


----------



## N10S (Sep 27, 2004)

IF52 said:


> I'd do the 650b bit. Maybe Quasimotos instead of Neos. Look on the 650b, 69er and new wheel trends forum, there are a few Tachyons rolling 650b over there.


I have seen those threads with the tachyons running the 650b's. That's what motivated me to go down this path. I have owned my share of gt's so it seemed like a good idea. I have been running drop bar mountain bikes for a while and liked the idea of an older vintage monstercross too.

I talked with the guy that ran the 2.3 neo's on his tachyon. According to him the 2.3 fits the front fine, but he did have to trim the side knobs a bit to fit the 2.3 on the back. Based on the width difference the 2.1 should fit fine. I never ride mud, so I am not really worried about having massive clearance. I looked at the quasi moto, but it doesn't get great reviews as far as traction and wear. Another option would be a set of the racing ralph's which are pretty narrow but are still an aggressive tread.

Thanks for the input, its appreciated and I am going to spend more time on the 650b forum doing some research on wheelset options.


----------



## Plum (Sep 14, 2004)

I am able to run 2.3's on my Quatrefoil (tandem) but I did have the frame converted to disc, so there's no caliper clearances to worry about. There's adequate clearance for the 2.3, but the 2.1 would a better fit. This is on the stock araya 700d rims..



N10S said:


> I have seen those threads with the tachyons running the 650b's. That's what motivated me to go down this path. I have owned my share of gt's so it seemed like a good idea. I have been running drop bar mountain bikes for a while and liked the idea of an older vintage monstercross too.
> 
> I talked with the guy that ran the 2.3 neo's on his tachyon. According to him the 2.3 fits the front fine, but he did have to trim the side knobs a bit to fit the 2.3 on the back. Based on the width difference the 2.1 should fit fine. I never ride mud, so I am not really worried about having massive clearance. I looked at the quasi moto, but it doesn't get great reviews as far as traction and wear. Another option would be a set of the racing ralph's which are pretty narrow but are still an aggressive tread.


Plum


----------



## N10S (Sep 27, 2004)

Plum said:


> I am able to run 2.3's on my Quatrefoil (tandem) but I did have the frame converted to disc, so there's no caliper clearances to worry about. There's adequate clearance for the 2.3, but the 2.1 would a better fit. This is on the stock araya 700d rims..
> 
> Plum


Thanks for the pics of the tires on the quatrefoil plum. Especially good to see them on the stock rims. That rear U-brake is definitely the weak link in the tire clearance chain. The disc brakes must be nice on the tandem. My santana picante has cantilevers and they do not do a great job of hauling the bike and two riders down from speed.


----------



## LIFECYCLE (Mar 8, 2006)

Thats a nice gt,very nice and if it was mine i would singlespeed it and put some riser bars on it.


----------



## N10S (Sep 27, 2004)

One of the guys djmuff did do a flat bar tachyon build with a new 650b wheelset and neo-motos. pretty slick build. You can check it out here:
http://forums.mtbr.com/showthread.php?t=416284&highlight=tachyon

I could imagine it being stripped-down to an SS with some wide flat bars with lots of sweep(like the ti flat-tracker I just sold a while back). Might be able to make it work without a tensioner as it has horizontal dropouts. They are short drop-outs though, so not too sure about that. My knees have been barking at me whenever I ride SS though, so a 1x is a happy medium for me. Overall a pretty versatile bike I think.

Thanks for the input everyone its really appreciated!


----------



## Plum (Sep 14, 2004)

I've been able to fit (with my disc converted frameset) up to a 700 x 40c tire in there as well, just FYI. Figured it would come in handy if we ever got a wild hair to do a tour with the bike..

Plum


----------



## N10S (Sep 27, 2004)

The disc setup really gives you some flexibility, what fork are you running?


----------



## Plum (Sep 14, 2004)

Ah, yes. Well, for a tandem, I was pretty much running low on fork options, since the original GT fork is a 395 A-c. I ended up with a DMR trailblade 9mm QR fork, as it was disc compatible and (relatively) short in the AC.

Other forks I looked at were the big dummy fork, which is a little shorter than the DMR, the Salsa Fargo Gen 1 for (the non-corrected one), the 1x1 fork, the Instigator fork and the Rawland 650b fork (the cool bi-plane looking one). The Rawland was the closest AC length,

Nobody (rightfully so) would really support or endorse the use of a single bike fork on a tandem, except the Surly instigator (which is longer than the DMR). For rigid mtb tandeming, you're kinda stuck with the dirt jumping type fork.

Eventually, this bike would either end up with a short sus fork or just being replaced with something easily suspend-able. Right now, it's getting used around town, so a sus-fork isn't a necessity. If we were to go touring or something, I'd probably get a fargo fork for road use, to get some braze ons, something the DJ fork is lacking. Either that, or a custom fork, but that cost is about what I paid for the entire bike (pre mods, anyway).



N10S said:


> The disc setup really gives you some flexibility, what fork are you running?


The disc setup was absolutely a good thing for us. We haul a chariot around most of the time as well, so it's nice having more brake than the u-brake rear. I'm running a 210f/185 rear Avid BB7.

Plum


----------

