@bobjonkman@sam@ascentale@moira oh yeah I had another look at the pics on the website and it uses backwards-facing, screw-adjusted dropouts. So that's not going to work with all the 3x7 frames in the recycling pile.
Also that's one chain adjustment for two chains, so the choice of chainrings is going to be limited by what gets both chains to the same length, and also the more-heavily-used chain is going to get loose as it wears, and you can't adjust it because the other chain is then too tight.
I was thinking about whether a pair of idlers would work: I've seen idlers used for single-speed conversions and they seem pretty good, I guess you could extend the idea to 2 chains. A sprung idler might not work well with the back-pedal gear shifts though, and two separate fixed idlers would be a bit of a maintenance headache!
@bobjonkman@sam@ascentale@moira I mean, that could be okay, *IF* the magic doodad is cheap enough for the target market *AND* you can just drop it in like a freewheel cassette, that's pretty cool.
A little shop could keep a pile of doodads and a pile of chains on hand and do conversions with only hand tools. The double chain thing is weird but it does allow for different ratios by fitting different chain rings, and unlike, eg: Sturmey-Archer or Shimano Nexus 3-speeds it doesn't need any torque reaction from the dropouts.
(It occurs to me, though, that any frame with dropouts wide enough for a freewheel / this thing is going to have the wrong kind of dropouts for chain tensioning, and also how do you tension both chains at once, unless you're just lucky I suppose?)
Anyway: It'd be a nice problem to solve, because there's a shitload of old bikes out there with decent frames and reasonable wheels, and there are charities already which ship these to developing countries where they can be turned into solid bikes *but* most of their derailleurs were a mess already and the rest are bent because that's what you get when you make a big pile of bikes at the municipal tip.
Bicycles are basically free. Useful bicycles are a bit more ...
@GeePawHill yeah, a conversation I have quite frequently
"okay roughly how many transactions per second are we talking?"
"we don't know."
"okay let's work that out so we can plan ..."
"we don't need to because we will implement on k8s using cutting edge caching technologies and service network architectures and therefore everything will be web scale"
"... okay I come up with 5 tps so allowing for ... wait, what?"
@Polychrome such a shame, she's actually been a great ambassador for Shenzhen ... okay so maybe it's not all about business but it's great to see the human side of a place a lot of us only know from shipping labels.
Nanoinfluencer & flâneur.Trying to get to the future before I'm too old to enjoy it."These days, though, you have to be pretty technical before you can even aspire to crudeness." -- William Gibson, /Johnny Mnemonic/