Getting rid of that pesky front derailer
My trek has been extensively modified, but the one thing that hasn’t been changed is the gear arrangement. Sure, I ripped out the old 52/42 rings and replaced them with a pair of 52/40 Biopace chainwheels, but I left the bicycle with 7 gears in back, 2 in front.
I don’t use a lot of these gears, except by default. I normally ride in the 52 tooth chainwheel (and then I use 5 of the gears on the rear cassette, because by the time I drop down to the 32 tooth cog I’m already in irons and need to switch the front out too) and only swap to the 40 tooth chainwheel when I hit a long or steep grade (and then I’ll use 5 of the slowest gears there.)
A lot of these gears duplicate, and are only used because I don’t like to take my left hand off the handlebars to (carefully) shift from alpine to flat and visa-versa. And because my Trek has been xtracycled, I neeeeeed that 40×32 low gear so I can creep up the side of long and steep mountains very very slowly.
But the hypothetical midlifecrisismobile isn’t going to be xtracycled – I’m going to have a handlebar/front rack bag and I’ll use that to carry all the stuff I drag along on my longer loops. So it’s going to be a whole bunch lighter. Light enough so I can (hopefully) not have to worry about having a 33" gear for pushing the mighty flamingo up those steep hills.
So, instead of having a 7×2 transmission on 700c×28 tires and the following gear inches
| 52 | 40 | |
|---|---|---|
| 12 | 116.0 | 89.2 |
| 14 | 99.4 | 76.5 |
| 16 | 87.0 | 66.9 |
| 18 | 77.3 | 59.5 |
| 21 | 66.3 | 51.0 |
| 26 | 53.5 | 41.2 |
| 32 | 43.5 | 33.5 |
I could take advantage of the slightly smaller 650b×38(or 33) on the midlifecrisismobile and go to a 1×8 gearset, for there are a whole bunch of interesting gear ratios I can get.
| 48 | 46 | 44 | 42 | 40 | 38 | |
|---|---|---|---|---|---|---|
| 11 | 113.5 | 108.7 | 104.0 | 99.3 | 94.5 | 89.8 |
| 12 | 104.0 | 99.7 | 95.3 | 91.0 | 86.7 | 82.3 |
| 14 | 89.1 | 85.4 | 81.7 | 78.0 | 74.3 | 70.6 |
| 16 | 78.0 | 74.8 | 71.5 | 68.3 | 65.0 | 61.8 |
| 18 | 69.3 | 66.4 | 63.6 | 60.7 | 57.8 | 54.9 |
| 21 | 59.4 | 57.0 | 54.5 | 52.0 | 49.5 | 47.0 |
| 26 | 48.0 | 46.0 | 44.0 | 42.0 | 40.0 | 38.0 |
| 32 | 39.0 | 37.4 | 35.8 | 34.1 | 32.5 | 30.9 |
Nothing matches exactly, of course, and I do either give up range at the top, the bottom, or both, but it looks like a 48 or 46 toothed chainwheel would give me more or less the range I’ve got with my current 7×2 setup. I’d lose some hypothetical top speed, but if I’ve got a bicycle that’s 25 pounds lighter, I should be able to gain some of that speed back by not having to drop into irons to get up those hills, and if I can do that there’s a fighting chance I can actually run a longer brevet and claw out enough time to park myself and sleep for ~8 hours in the middle of it (right now the mighty xtracycle takes about 11 hours to run a flattish 200k. That’s 7.5 hours in a 600k, which is not enough for a good night’s sleep in the middle) which, if past performance is any indication, is an important part of keeping me coherent, civil, and not ill.
And I’d not have to shift the front derailer while I was doing this, though I guess I’d have to do something about the protruding shifter mount on the downtube.