From D7 to T10, part 2: Rear drivetrain pieces

Once the foundation of Bino’s drivetrain, the rear hub, was replaced, upgrading the rest of the drivetrain became a much more straightforward process.

With more cogs jammed into the same length of space on the rear hub, a more appropriate, narrower chain is needed. On went a Shimano 105 CN-5701 10-speed chain.

I managed to score a second-hand Shimano Tiagra RD-4600-GS rear derailleur. This is a medium-cage unit, as denoted by the “GS” suffix on the model number.

Finally we come to the shifters.

These are Shimano Tiagra SL-4600 and SL-4603 trigger shifters for a 3×10 drivetrain.  For this phase of the upgrade, I will need only the rear shifter. This particular shifter set is necessary because road bike and mountain bike shifters and derailleurs stopped working nice together when Shimano introduced DynaSys for its 10-speed mountain bike stuff.

With all these parts installed, Bino’s rear drivetrain upgrade is complete.

Initially I had concerns with the length of the derailleur cage being vulnerable to damage. Because of the small wheels, the lower end of the cage might strike the ground, the tire or the wheel depending on what cogs are selected. So far, this hasn’t been a problem.

The stock handlebar grips are uneven length because of the stock grip shifter on the right. They were becoming loose anyway, so I fitted Ergon GP3-S grips with integrated bar ends.

So how has Bino changed after the upgrade?

The 30T max cog is a welcome bailout gear, and the LitePro hubs’ pawls and ratchet mechanism are noticeably louder when freewheeling – something I’m not too fond of. The noise is a tradeoff for better engagement than Hyro’s stock hubs, putting down drive at smaller crank angles. The Ergon bar ends are very useful, too, giving a welcome secondary hand position similar to riding on the hoods of a road bike. The trigger shifters mean that instantly dumping six cogs is a thing of the past, and a bit more forethought is required when bike-commuting, but the ergonomics are much better.

Other than that, though, the change in gear range isn’t as pronounced as I had thought. For training purposes, I try not to engage the 30T cog, leaving it to the next-largest 27T cog to spin up slopes. The 12T cog does increase top-end speed. However, I’ve realized that Bino is happiest operating within 80% of his potential. I now have Hyro for faster rides, so Bino is free to ride at a more relaxed pace.

Still, I don’t think I’m done upgrading this bike. I still have a perfectly functional left shifter in my parts bin, and I can see potential improvement in the stock V-brakes, whose return springs are living on borrowed time. It might take a while, but stay tuned.


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