Chainring shift technique when pulling a child in a trailer
 

Hi. Right now, my family is enjoying a summer vacation in a very hilly area. We've been very happy with the Retrospec two-wheeled trailer we've been using to take our two-year-old with us to the lake and around the area. However, there's one really tricky spot on the road near our rental house that combines a deep ravine, steep on both sides, with a sharp turn at the bottom of the dip. My wife and I are both riding older road bikes (1962 Atala, 1984 Peugeot) that I've retrofitted with modern triple cranksets, upright bars, and friction shifters (3x5 for her, 3x6 for me). We're finding it really challenging to make it up the opposite side of the ravine without going too fast to take the corner with the trailer attached. The extra weight of the trailer makes shifting on the uphill pretty difficult -- I actually broke a chain doing it, a couple days ago -- but if I shift down to the smallest chainring while I'm still on the downhill, I won't have any power coming into the uphill and will lose most of my momentum. What's your shifting technique in a circumstance like this?

It does depend on the specifics as far as the difference of the size of sprockets you have but usually I shift up at least one cog in the rear before dropping the chain down to a smaller chain ring to lesson the drop.

Be careful with too much speed around the hairpin corner pulling a trailer. And, of course, watch for curbs and major bumps that your trailer wheel could catch at speed and flip the trailer.

I don't ride a "triple" very frequently. But, I will at times drop to the lowest ring on front, then moderately cross-chain (small/small ring combo), then slowly shift down to lower gears using the rear only.

One thing I've noticed is the newer freewheels and cassettes shift much smoother than the old freewheels. But, I do think there is somewhat of a tradeoff for more rapid wear.

Find something with lower gears and trigger or grip shifters. A hybrid or a 90s MTB. You don't have to get married to it. Use it for the two years you have the trailer, pass it on. Don't risk capsizing your kid for your old-bike affectation

Just shift into the small ring before the hill if you're going to need it to get up (assuming there isn't a flatter spot to sneak a shift in) and accept that you're going slow on the approach to the hill. Front shift under power is just asking for problems, as you've proven.

Not an affectation -- these are bikes that I and my family already had around (in the case of the Atala, actually since 1962) and it was way cheaper to change the crankset than to buy a new bike. At any rate, I don't see how the situation would be different with lower gears or different shifters.

I see three options.
The first is to learn to shift really well on an uphill. In short you have to stop applying load, but keep the pedals turning, as the chain transitions. I describe it as coasting, but with the pedals still turning. If you get this correct you can also do a nearly silent shift in either direction with a friction shifter. One of the keys to this is to start the shift early enough that you’re still moving fast enough to still be in the correct gear after the downshift.
Second, while it isn’t as smooth, it is tons easier to shift a modern cassette with ramps and pins under load than an old straight toothed freewheel. It’s still bad practice, but it works without issue 98% of the time.
Third, have low enough gearing that you can make it up the hill from a standing start at any point.

For front ring downshifts you can do it in advance and cross chain for a bit as described above, or just put a Deda Dog Fang on your seat tube below the front derailer. Properly adjusted you can’t drop the chain downshifting if you try to.

Going through a turn at a speed that risks tipping the trailer sounds like a solid no-go for me. One of the cardinal rules of tandems is that you must never, ever, crash. You don’t want the trusting stoker to ever get injured as a result of the captain’s actions. I don’t see a trailer as any different.