1994 GT Xizang Geometry

[bryanus]

Does anyone know where I can find a geometry specsheet for the 1994 Xizang frame (16")? I looked i the catalogs, but they didn't see one. The 1998 catalog has one, but I'd like to compare the 1994 to that year frame, as the later years were made to accept v-brakes vs. cantis.

TIA.

 

[SeeingisBelievingGTMuseum]

You can easily run v's or canti's on a 94 Xizang. I think I posted the 94 Tech Shop catalog in the catalog thread a few years back....search it, there would be a chart in that catalog.

 

[bryanus]

Thanks GM, I didn't see the Tech Shop catalog at first glance. I was able to compare the geometry from a '93 and a '98 from the available catalogs. Interestingly, the specs are exactly the same, save for the seat tube angle on the '93 is listed at 73.5 versus 74 on the '98. I feel that's actually close enough to call it a 74-degree, considering the top tube and seat tube measurements are the same for both.

Having the same geometry in both '93 and '98 also infers to me that GT made no changes to their frames to accommodate suspension travel variances over the years. '98 would have seen the Original Blue 63mm SID and between '93-'97 would have been the likes of the shorter travel Mag21's and 50-63mm Judys.

 

[SeeingisBelievingGTMuseum]

Having the same geometry in both '93 and '98 also infers to me that GT made no changes to their frames to accommodate suspension travel variances over the years. '98 would have seen the Original Blue 63mm SID and between '93-'97 would have been the likes of the shorter travel Mag21's and 50-63mm Judys.

Not so. If you remember many of the early suspensions forks first produced whether 48mm or 80mm travel had around a 405mm Axle to crown. Hence there was no need to drastically alter the geometry until more advanced fork designs and longer travel became standard. Also a 98 SID fork could have also been an 80mm "long travel". With the increase of travel between 48 and 80mm most of that travel difference was happening within the upper and lower legs thus not affecting the Axle to crown drastically. That's the way it was explained to me.

 

[bryanus]

I'll have to look over the A-C measurements from various Judy's and SIDs I've had and do some comparisons and see what I can deduce from those.

Looks like we're the only two Stateside users who haven't passed out from too much turkey! gobble gobble!

 

[JamesM]

I know the lower spec bikes (Karakoram, Tequesta etc.) came with 425mm A-C rigid forks in 98/99 where as early 90's frames came with 395mm ish. That would suggest the geometry was corrected for 80mm (or there abouts) sus forks.

 

[SeeingisBelievingGTMuseum]

Looks like we're the only two Stateside users who haven't passed out from too much turkey! gobble gobble!

Know not to reach the pass out state...did eat too much though.

 

[bryanus]

ok, some measurements I've made over the years:

50mm Judy XC 413mm A/C
'97 Judy XC 63mm 425mm A/C
'98 SID @ 63mm = 435mm
'03-07 SID @ 80mm = 442mm
'08 32mm SID 80mm/100mm: 453mm/473mm

Since the '94 Xizang would fall into the 50mm Judy category with an A/C of 413mm (or perhaps even the 46mm Mag21), and the '98 Xizang would have been fitted with a '98 Blue SID with an A/C of 435mm, where is the "suspension correction" actually occurring in terms of geometry changes? From the catalogs of the '94 and '98 model Xizangs I looked at, all measurements were the same.

So what I'm asking is, are the frames of the non-U-brake models of the Xizang ('93-'99) exactly the same in terms of geometry? It would appear so. One way to account for the longer travel of later forks would be sag. The earlier Judys were basically set up with very little sag, whereas the later SIDs used more sag in their setup. Using an '08 SID (80mm, A/C of 453mm) on a Xizang with the correct amount of sag, brings the A/C back down to 425mm, which is the A/C of the 63mm Judy.

 

[SeeingisBelievingGTMuseum]

Google axle to crown...there are a number of places with accurate lists published. I know I've seen a couple at MTBR, pinkbike and I think even in the MBA Archives.

 

[JamesM]

You say all measurement for the '94 and '98 mm frames are the same. But head and seat tube angles quoted by manufacturers are only correct at one fork a-c length. It maybe that these angles for 94 frame are with an a-c of 395mm and the same angles quoted for the 98 frame are with an a-c of 425mm. This would mean the later frame actualy has steeper angles, everything else being equal.