Early Derailleur (I think)

Graham

Cruising
Feb 4, 2014
18
13
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Minato-ku, Tokyo, Japan
#1
Does anyone have any knowledge of how this might work? There were two bikes displayed on the wall of a restaurant I was in last night; one was a normal fixie and the other had this odd gearing. I`m told it is an early form of derailleur; and that you pedal backwards to change gear; but do we know more? Restaurant was Les Valseuses in Prenzlauer Berg, Berlin so a bit off the TCC radar screen perhaps.
 
Likes: bloaker
May 22, 2007
3,612
1,444
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Kawasaki
halffastcycling.com
#3
Pedalling normally will turn the smaller sprocket in the forward direction. Reversing the pedalling action will turn the larger sprocket in the forward direction. Presumably there are two independent and opposing freewheels allowing the non-engaged sprocket to coast. Ingenious.

Edit: once you see what's happening, it's easier to find
http://en.wikipedia.org/wiki/Retro-direct
 
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Likes: bird

GSAstuto

Maximum Pace
Oct 11, 2009
945
242
103
tokyo
www.roadfixie.com
#5
Mike is correct - this a retro-direct gearing. You pedal forward for the higher (faster gear) and backward for the lower (slower) gear for climbing. One way to avoid 'flip flop' on the steep hills... the later versions usually had a front chainring derailler so you could actually get a 4 speed with very wide range!
 

Cactaur

Speeding Up
Feb 3, 2014
98
23
28
#6
Very cool. It's going to mess with peoples minds nowadays to see someone pedaling backward up a hill.
 

bloaker

Maximum Pace
Nov 14, 2011
1,551
1,224
433
Miura, Japan
#7
So,... can your coast? It seems it would be possible and if you pedal forward or back, as long as you pedaled slower than the bike, it would be fine. But having never seen this before, I am just trying to think it out.
I would be awful if there were any accidental engagements.
 

TCC

Tokyo Cycling Club
Jun 30, 2013
2,362
1,291
133
#10
Both the freewheels engage in the same direction, so freewheeling behaves normally.

I would like to see how the freewheels attach to the hub shell. I suspect two co-axial threaded tubes with the smaller extending further than the larger