A bout of purism

[DavidCH]

OK... I got on my knees today for the first time to see what sort of improvements are needed aerodynamically and oddly enough the biggest eye sore was the rear derailleur; it's way weird with the smallest sprocket giving the most drag. Even the main housing of the derailleur is like the sail to a yacht.

Well how do you fix it? Well one could radically reverse the cassette around for slightly less drag but the main mechanism is still a sail. Perhaps totally invert the setup and have the derailleur above the chainstay then to go forward , you would have to spin your legs backward.

I can't see that happening. Then I remembered some time ago I saw a new mountain bike configuration so I took a closer look today. I love the derailleur but the chain retention mechanism looks a bit OTT. The nights are getting longer and the idea of fascinating projects are getting stronger.

 

[Henri]

I like the idea of the Supre Drive for velomobiles and 20" rear wheel drives, where there is very limited height to work with till you reach the floor or the chassis. I am not sure, jf it is worth it on anything else, other than maybe those mountain bikes it is made for. It needs a completely different mount, so a bike built for Supre Drive is not built for conventional derailleurs and if Supre Drives are ever not available anymore, you can only try to keep your current one running as long as possible.

The nights are getting longer and the idea of fascinating projects are getting stronger.

But if you should be able to modify a bike to take Supre Drive you should be able to get it back to taking conventional derailleurs, if you ever need to?

I love the derailleur but the chain retention mechanism looks a bit OTT.

Well, the large upper idlernis only there because of the suspension design, I think the key word is "high pivot rear suspension". And the chain tensioning is only done by the one pulley that articilulates around the chain ring. In this shown configuration it has a lot of room to come across the chain ring, though. I guess, on our current configuration it might only get about ¼ of number of teeth on the chainring as capacity. on a 52t that would be 13t, so only allow for a cassette of 11-24 or so, with only one chainring. Inthink the derailleur motion should take some chain as well, so maybe 11-40? Might be enough for many of you. With another idler right after the tensioning pulley, its capacity should be effectively doubled, so maybe 11-52 od 10-50 or so might actually work then.
But with a totally different tensioner that leads the chain up and down the chainstai with one fixed idler and one moving pulley, you could get as much capacity as you might need for any cassette plus what a front derailleur can actually shift in chainring difference.

 

[DavidCH]

One of my older projects was putting some gears on a fixie. I like the aerodynamics of a fixie as the drive wheel hub size is a lot smaller than 135mm , part of the gear I bought for the project was a chain rectifier so I am thinking that this could be mounted by the chainring on the chainstay. I have sent an email to cedric to see if I can buy the rear derailleur and then I would have to play around and make a suitable hanger to fit the vendetta

 

[Rampa]

The lower "idler" pulley is the lower jockey wheel on a regular derailleur. The upper is for suspension to reduce pedal kickback from the high pivot.

 

[DavidCH]

Well, I have seen something that could be a half way house. Essentially the deuralleur minimises chain drag on the smallest sprocket!

I could also take the long cage off and try the chain tensioner idea too.
It's the ingrid rear deuralleur. (Interesting name for sure)