On Wednesday, August 5, 2020 at 12:37:10 AM UTC+1, Tom Kunich wrote:
On Tuesday, August 4, 2020 at 11:06:48 AM UTC-7, sms wrote:
On 8/4/2020 9:12 AM, AMuzi wrote:

snip

https://www.ebay.com/itm/202930103988



We agree.
That does exactly the same job in the same way as a used Tourney
derailleur with the stop screw turned in.
If you're putting that device on a bicycle with double or triple front
crank then it makes some sense, but for single front crank why would you
not just shorten the chain?

That description is quite amusing: "This single speed converter is very
suitable for the bicycle that suits for mountainous terrain" and
"Suitable for people who like cycling."
If you have vertical drop-outs you invariably have a slack chain that can throw the chain off of the chain ring. So whether you have one, two or three rings you're stuck using a chain tensioner of some sort. Andrew probably has an entire junkbox full of useful old derailleurs that would take care of the problem but since I've been cleaning everything out I'm stuck purchasing new.

All my current bikes have horizontal sliding frame ends. But they can be quite as limiting as vertical dropouts. For instance, what's commonly known as track ends cannot be bolted up tightly enough to work with a hub or bottom bracket gearbox with force multiplication greater than say the Shimano Nexus HGB, and certainly not with the more puissant centre motors.

Rohloff's in-house design of dropout, blueprints available free of charge, oddly enough is a dropout, vertical. But it sits on a machined aluminium piece which slides in closed slots on the frame ends, and is confined to the slots and thus to horizontal sliding by a tongue on the actual axle hanger. The non-drive side of the axle hanger has an extra long axle slot to hold a stud about half an inch by a quarter which is on the gearbox itself and this does duty as the torque reaction arm. It is probably just as well the Rohloff likes a slack chain... A tightly packed installation, though, when you come to a touring bike. Close up photos on the eighth page of this PDF: http://coolmainpress.com/AndreJute'sUtopiaKranich.pdf

Andre Jute
Pathfinder