This build is moving quickly at the moment which is remarkable for me! I’ve got a Shimano 600AX group that will complement this frame beautifully…
If you have been following my posts about dating SBDU frames, you will see that SB4944 dates from the very start of 1982. The perfect companion for this frame would also be from the start of 1982, the newly released Shimano 600AX series components.
The feature above was the last page in the 1981 Shimano Bicycle System Components catalogue and was an announcement of things to come…
The 1982 catalogue listed both the Dura-Ace AX and 600AX systems.
However, this isn’t going to be a straightforward fit. My frame will require a few small ‘modifications’. These modifications will require files, emery paper and some touch up paint.
The 600AX rear derailleur is fed by the cable from the top of the chain stay. My frame is already suited for this as the gear cables are routed above the bottom bracket through brazed guides… so not a problem. However, this derailleur does not require an outer cable stop, or any outer cable. The theory from Shimano was that compression and movement in the outer cable would affect the precise and direct response that Shimano wanted to achieve. So they simply designed a mechanism for feeding the inner cable directly to the derailleur – more direct, more responsive, more aero dynamic and less weight (Shimano’s words, not mine)! The cable stop is not required so will be removed.
The gear levers are the biggest problem to work around. My frame has a top mount single boss for mounting levers. This is a slightly different shape and profile to the type of mount on the 600AX levers. So I’ll be using my Dremil to adapt both the lever mount and frame mount to allow them to sit together properly.
The 600AX seat pin that came with the group is the correct size of 26.8, and the group also came with the AX bottle and cage which was shared between the Dura-Ace and 600 groups.
The final issue is the front derailleur – thankfully I have the choice of two. I have a band on 600AX option or a braze on Dura-Ace AX option. My frame has a braze on fitting so I’ll attempt to make the braze on type fit. However, it may be that the bottom of the braze on frame fitting itself may need to be shaped to avoid the cable pull. If that fails, the braze on will be removed and I’ll use the band on type.
The brakes aren’t an issue at all and will fit directly without any modifications.
The bottom bracket axle and cups are in good condition so I’ll just pop in new bearings and grease. I’ve always liked these cranks and pedals, and apart from the pedals requiring a regrease, they seem in good condition.
The headset is also in very good condition and is also the correct dimensions for my frame/forks of 26.4/30.2 – it even comes with the clear plastic AX cover.
Hubs are 36 hole and only need new bearings and grease. I’ll need to test the cassette that came with them as it may be a little bit worn. However, these individual sprockets can be turned around to provide a brand new face for the chain to pull against.
To finish off the group, I have the 600AX handlebar stem and brake levers. The hoods aren’t in great condition but should do for now.
The AX series components came with a flurry of new designs and terminology including…
Uni-Balance Mechanism Special Front Hub Structure Direct-6 Mechanism Direct Cable Mechanism Super Finish Treatment New Positive Mechanism New Trap-Ease Mechanism With Lateral Link Design Chain Release Indent New Para-Pull Mechanism One Key Crank Release Offset Crank Arms W-Cut Mechanism Pedal DD Mechanism
I’m sure all of the above makes sense to Shimano! I’ll get my PDF copy made into a Jpeg and uploaded so you can read about what all these things actually mean.
To finish this build I’ll use a period turbo saddle and Mavic rims. Once it is finished I’ll be out on it but that will not include the skin suit! Thankfully that skin suit did not come with the group and isn’t necessary to complete the build!
Don’t think that I’ve ever seen that rear mech but I’m sure Ive got some of those pedals lying around somewhere!
It is beautifully designed stuff and way ahead of its time for 1982.