When my rear dérailleur failed during PBP reducing me to two gears, I admit that my first reaction was to direct some harsh words at the SRAM eTAP Red groupset. Eventually I reached a philosophical acceptance and I started to think about alternatives. Later, my friends on fixed-gear bikes suggested that I still had one more gear than I needed! While I admire the simplicity of fixed-gear or single-speed bikes, I don't think there's room for one in my garage just yet and I'm not sure my knees would take it. However, riding for a few hundred kilometres with only two gears did make me think about how many gears I need.
For the last 200km of PBP 2019 I disabled my rear dérailleur by removing the battery to prevent accidental shifts. I left the chain in the 3rd-lowest gear, with 26 teeth. Coupled with the front rings of 34t and 50t, this gave me two gears. According to this bicycle gears calculator the lower ratio was 1.32 and the higher one 1.94. Now those two numbers mean about as much to me as to the average cyclist. What they're useful for is comparison with other possible setups. Another way to describe it is that I lost my bottom two gears and my top eight gears. I was a little slower as a result, but I was surprised how little difference it made. Admittedly it helped that the PBP course is not very hilly. I did have to stand up and grind slowly on the way to Mortagne and could have gone a little faster down hill rather than spinning out at 30kph. However, after 1000km I was in no state to be pushing hard in a high gear.
OK, "need" is a relative term. I imagine bicycle gears are a tiny point vanishing at the top of Maslow's hierarchy of needs, but for the riding I do, what works? Those two gears may have been fine for the end of PBP, but for more general use including fast group riding and steep hills, I'd want a wider range. For the last five years my usual road bike 2x11 setup with 50t-34t front and 11t-32t rear gives a lowest ratio of 1.07 and a highest ratio of 4.59. The only time I changed this was to a lower ratio of 0.69 for a steep Everesting and I was very glad I did.
After some playing around with the calculators I worked out that I can get something very close to my original compact 2x11 set up with a single, 44-tooth ring on the front and a wider 11-42 tooth cassette. My thinking is that I won't really miss the top two gears. In fact it's not even two gears, as 4.04 is still higher than 3.61 - my old third-highest gear. It's more like I'm losing one-and-a-bit gears. I rarely use such high ratios, especially on long rides. They would typically be for an all-out sprint slightly downhill or with a tailwind. However, the bottom end of the gear range is essential to keeping my average speed up on steep climbs when tired. My lowest gear will now be fractionally lower than before, but not enough to notice.
A 1x11 setup on a road bike is unusual, so it took a bit of thought as to how to do it. In particular it's hard to find a rear road derailleur which will allow such a large cassette. One option is to get a purpose-made 1x system like SRAM's Apex 1. Even putting aside my recent bad experience with SRAM, some online research suggests they are not as robust as other brands and sourcing spare parts would certainly be harder than Shimano.
So what can I do with Shimano? The medium cage 105 derailleur will stretch to 11-34 teeth on a cassette. As you can see from the table above, that doesn't give much gear range. With a bit of research I discovered the Wolftooth Roadlink DM. This extends the reach of the cassette to allow 11-42 teeth - a much larger range. The Roadlink DM has been tested with the latest 105, Ultegra and Dura Ace derailleurs. I couldn't see any advantage to Ultegra/Dura Ace except for saving a few grams, so went for the 105. I wasn't sure how good the shifting would be, but compared to my previous setups it's a relatively inexpensive experiment. - Hope Retainer Ring 44T (for 1x setup) - £35 - Single ring chainring bolts - £10 - Shimano 105 R7000 11 Speed Rear Derailleur Silver Medium (GS) Cage - £33 - Shimano 105 R7000 11 Speed Shifter Set Silver Pair - £126 - Wolftooth DM - £30 - TOTAL - £234 Fitting was fairly straightforward, it seemed. I attached the Roadlink DM to the frame's derailleur hanger, then attach the 105 derailleur to that. I looked at it a few different ways but there's only one way it can fit. The Roadlink DM has a tab sticking out towards the wheel which stops it from rotating downwards as it catches on the derailleur hanger's hook. You can just see it at the top of the photo below. But it wasn't quite right. I tried shifting through the gears, but couldn't quite get into the biggest ring. I adjusted the various screws to their limits but it still wouldn't quite go. Then I realised that the derailleur had a spacer in it (green arrow below). Swapping this with the plate attached to the hanger (red arrow) had the effect of moving the whole derailleur inwards towards the wheel by a few mm. That was enough to get the shifting working as it should!
On the first ride I noticed that although the shifting worked properly, the lowest gear was a bit noisy, like cross chaining on a 2x11. Of course that's exactly what it was. I'd fitted the single ring on the outer side of the crank spider (if that's the right phrase), where the larger ring would normally go in a 2x11 setup - as shown in the picture above. It looks neat in this position, but I think the chain line is not right. Below left shows what it looks like with the chainring mounted inside the crank spider, where the small chainring would normally be. It's a bit subjective, but it seems like the gears are now much quieter in the lowest gear. When I'm using this cog and grinding slowly up a hill is when I'm most bothered by noise and drag, so it's a big relief to have it working better. I haven't noticed any chain line problems in the highest gear. Putting the chainring in this position does make it pass rather close to the chainstay, as you can see below-right. I probably couldn't use a much bigger ring like this, but it's fine for now.
I've now ridden about 500km on the 1x11 setup. I experienced one chain drop, going over a bump when in the highest gear and pedalling backwards (I don't know why), but otherwise the narrow-wide "retainer" ring has done its job well and the setup has been reliable. It has taken some getting used to having a single control for shifting and, especially in the lower gears, the steps between them are larger than I'm used to. Perhaps that would make it unsuitable for racing up hills. Overall I'm happy with the setup and intend to keep using it for now. I think the thing I appreciate most is the simplicity of that single control. I no longer have to worry about when to switch between the front rings and back the other way on the cassette. One way for higher gears, the other way for lower.