There was a steel Transmission
from http://solexium.free.fr/produits2.htm. There were two kits available
on their website, one kit with a fixed diameter,
the other kit with a choice of three diameters. Unfortunately
it seems that they no longer produce this item.
Back in October 1998, there existed
a Tabouret "Competition
Solex" Catalogue (Tabouret Accessoires,
4 Impasse Pierre et Marie Curie, BP 31, Saint-Yrieix,
16710, France) selling reinforced re-designed Crankcases,
Crankshafts and Bearings, Reed-valve Inlet Side Plates,
Dell'Orto Carburettors (up to 21 mm), ribbed steel Transmission
Rollers (40 mm to 48 mm diameter), 5-port Cylinders
and Malossi Cylinder Heads, Electronic Ignition Rotors,
Exhaust Systems, etc. Unfortunately, the company no
longer appears to exist.