With the memory of the shifting issues on last week’s ride fresh in mind, and with a belly full of the appropriate beverage, I decided it was time to change Hornsby from the SRAM drivetrain inherited from Dionysus and go instead for a roughly equivalent Shimano set-up. To be honest I’ve been contemplating this for a while, and the recent misadventures just provided me with an excuse. The SRAM Apex I drivetrain has been good but never great, and I’ve long wondered if the Deore would be more satisfactory.

It was a good time to make the leap because the latest Deore drivetrains are 12s Di2, and I was looking for 11s mechanical. I was able to score the fully matching drivetrain for a very reasonable price. The new bits also match the existing Deore hubs and brake levers.

Hefty Hornsby

Before beginning I put Hornsby on the scale: with bag, pump, lights, etc., we’re talking a whopping 12.97kg. I was eager to see what affect the swap would have.

The next step was to take off the current derailleur and check the hanger alignment. I’d done this recently, after getting the derailleur tangled up in November, and so only a little fine adjustment was needed.

With the rear derailleur off, I compared the weight to the new unit. And I continued with that, just pulling the bits off the bike from easiest to remove to hardest, and put them on the scale together with the replacement. I knew some of the newer bits would be heavier — the rear cassette has a 42-tooth maximum compared to 40T for the SRAM — but I didn’t think the crankset (with a much smaller chainring) would be so much heavier. Well, it’s a hefty unit, designed for mountain biking.

The only bit with a clear weight savings was the bottom bracket, which came in 14g lighter than the one from SRAM.

I weighed the Deore cassette with the plastic placeholder hub still inserted, to make it easier to install on the bicycle hub. Once I installed the cassette I weighed the plastic bits at 6g, so we can deduct that from the cassette’s total.

The final bits on the scale were the cranksets and bottom brackets.

LibreOffice Calc tells me the sum of the SRAM parts comes to 1,861g, while it’s 1,982 for the Deore: an increase of 121g. That will certainly put Hornsby over the 13kg mark!

Reassembly

Disassembly was nearly painless. I had to remove the brake lever to get the shifter off the handlebar, and for a moment I thought I’d have to undo the cable. After a moment’s thought I rerouted the cable around the handlebar bag and all was good.

José had tightened the crankset when we built Hornsby, and I had a moment of panic thinking I’d need to ask him to undo it. No fear — I was able to do the job with just a bit of excessive force and one busted knuckle. The pedals came off easily enough after that, even though I’d forgotten to take them off when the bike was still on its wheels on the ground where I’d have more leverage.

I’d had some questions meanwhile about the fit of the rear derailleur — it’s got a bit that sticks out far enough to collide with the cogs if things aren’t just right. I downloaded the service manual and it showed me one bit I’d got in the wrong place. Correcting that helped, but the thing still looks like it’s going to mash into the cogs. After sizing the chain and trying to give it a pass through the jockey wheels, I had a couple of more looks and decided to leave things as they are for the day. I’d much rather get back to it tomorrow and make a fresh start to ensure I had that alignment correct before it causes more issues.

Nana returned from the sauna as I was cleaning up all the tools and parts from the day’s work. I’ve stashed all the SRAM components for possible reuse on another bike — they may find a home yet. After I got home from dinner I had another look at the Shimano service manual and realized I’d cut the chain a couple of links short. I’m going to blame this one on Calvin Jones, because he’ll never see this. But having discovered that makes me feel even better about not just forging ahead to the end today.