RE: ST Gearing

["Keith Tynan" <keith@xxxxxxxxxxxxxxx>]

It must be that time of year again, when everyone sits around pontificating
rather than riding....

Can anyone enlighten me as to the stock gearing of the ST in the US? There
seems to be a lot of variation in listers' ratios. It should be easy enough
to find out, as it's in the VIN:

A workshop manual I had for my old '94 Trophy 900 gave the following meaning
to the various components of the VIN, e.g:

SMTTF600MGX100001
SMT................Manufacturer ID, i.e. Triumph
   TF..............Model type )_ Sprint ST=TF600 (1994 Trophy 900=TC300)
     600...........Model data )
        M..........Motor Number - equates to engine config
                                  (#cyls*bore/stroke):
                                  A=4*76/55, B=3*76/55, C=4*76/65,
                                  D=3*76/65 .... M=3*79/65
         G.........Final drive ratio - A=17/52, B=17/50, C=17/48,
                                       D=17/46, E=17/44, F=18/45,
                                       G=18/43, H=19/43, J=19/42
          X........Year of manufacture - L=1990, M=1991, N=1992,
                                         P=1993, R=1994, S=1995,
                                         T=1996, V=1997, W=1998,
                                         X=1999
           100001..Chassis number

As for the advantages and disadvantages of various gearings, I find my stock
18/43 gives me good acceleration in 1 and 2, yet gives me a low motor speed
when cruising (under 5k @80).

A purely theoretical examination of the performance would suggest the
following statistics. The variance in the acceleration times occurs when a
gear change occurs at the top of the acceleration window (i.e. 60 or 100).

Front Back  Ratio 0-60  0-100 top
- ----- ----  ----- ----  ----- ---
19    43    2.26  4.06  8.45  166*
19    45    2.37  3.61  8.44  158*
18    43    2.39  3.59  8.41  157
18    45    2.50  3.66  8.23  150
17    43    2.53  3.64  8.20  149
17    45    2.65  3.54  8.27  142

* Speed at max revs. Wind resistance limits actual max to ca. 157 mph.


Hope this helps.

BRG (Winter anorak)


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