rigidftw
Retro Guru
First ride proved that the Roox Roller-Coaster is not a chain tensioner. It's a chain guide.
I'd need it to move more than the spring could handle. It bent as soon as there was enough tension on the chain for it to not jump over the cog.
And this while the chain was not even long enough in order for the rear end to move through all of its travel.
Grafting a different spring onto it, one from a Paul Melvin, made no real difference and the setup extremely inconvenient.
This experiment failed.
But then I remembered I had a suitable tensioner on another bike. I had to kindly ask the in-laws for them to bring it with them when they came to visit in saturday.
It's the cage off a 10s Shimano Zee rear mech mated to a carbon plate. Pretty simple, very effective. I got that one used a couple of years ago.
I added a chain link and checked chain length this time, though.
