I’ve also seen (can’t find it now) a setup with the drive side of a left drive bmx crank mated with the drive side of a right drive crank and a hub that was threaded on both sides. The chain on the left was ran in a figure-8 through a piece of plastic tubing to prevent the chain from rubbing on itself.[/quote]
To Jack: Both freewheels are going forwards. Utilizing the front chainrings would likely be very easy for a 2 speed bicycle if you used derailleurs. But to be able to pedal forwards and backwards, this is the only way.
To Agave: Yes Pierre’s setups are very nice. I used his website extensively in trying to understand the system. I was trying to avoid having to modify the chainstays or have a huge hunk of metal sticking out anywhere.
Do you have a picture of this? We may be talking about the same thing?
Also thanks for all the comments guys! I’m just stoked that I can ride the bugger without dropping the chain every 18 seconds like the earlier versions.
That was the video that started the chaos of my project. You don’t know how many times I would yell out “DAMN YOU KINGSLEY MANDRAKE!” during the drivetrain and hub assembly.
OK, how about chainrings on both sides of the crankset (seen this somewhere)
Flip flop hub so you can have a freewheel on both sides.
The only part I’m not so sure about is the cross-over for the retro side.
Seems like a pair of derailleur pulleys side by side could keep the chain separate when it crosses over itself, but I have no idea of whether this would interfere with the chainstay.
OK, how about chainrings on both sides of the crankset (seen this somewhere)
Flip flop hub so you can have a freewheel on both sides.
The only part I’m not so sure about is the cross-over for the retro side.
Seems like a pair of derailleur pulleys side by side could keep the chain separate when it crosses over itself, but I have no idea of whether this would interfere with the chainstay.[/quote]
Figure8 the chain and use plastic tubing in the area where the chain crosses itself (like the tubing that is used for chain guides on some recumbents). Using the big ring on this side would give you more chainstay clearance. Or you can add all the crap that Pierre used on his double chain bike. A tandem crank gives you rings on both sides or use half of 2 cranksets. You could figure8 the chain and do something with the derailleur pulleys as you mentioned on the non drive half of the chain. …Build something Jack, I’d like to see this done without having to do it myself.
OK, how about chainrings on both sides of the crankset (seen this somewhere)
Flip flop hub so you can have a freewheel on both sides.
The only part I’m not so sure about is the cross-over for the retro side.
Seems like a pair of derailleur pulleys side by side could keep the chain separate when it crosses over itself, but I have no idea of whether this would interfere with the chainstay.[/quote]
Jack what are you trying to accomplish exactly? If you wanted 4 speed you could run a front derailleur easily. You would just need to watch your chain tension.
If you ran cranks on both sides and freewheels on both sides, one would never engage unless you removed the chain from the bigger gear on one side.
A good friend of mine built one of these a year or two back. It was pretty fun to ride. I remember when he was explaining it to me it was pretty easy for me to see how the chain routing worked, and then he just said “… and I had to do lots of shit to the hub” and left it at that.
This is exactly the sort of thing I can’t understand how anybody could ever do unless they were stoned the entire time they were building it. I’m pretty sure he was when he built his.
[quote=EivlEvo][quote=JackD]WTF was I thinking of…?
OK, how about chainrings on both sides of the crankset (seen this somewhere)
Flip flop hub so you can have a freewheel on both sides.
The only part I’m not so sure about is the cross-over for the retro side.
Seems like a pair of derailleur pulleys side by side could keep the chain separate when it crosses over itself, but I have no idea of whether this would interfere with the chainstay.[/quote]
Jack what are you trying to accomplish exactly? If you wanted 4 speed you could run a front derailleur easily. You would just need to watch your chain tension.
If you ran cranks on both sides and freewheels on both sides, one would never engage unless you removed the chain from the bigger gear on one side.
Im very confused.[/quote]
Cranks both sides. Chain on one side crosses so that the chain running off the bottom of the chainring pulls directly on top of the freewheel. Somewhere in-between they have to cross… so you just need a guide to keep them from messing with each other and keep them off the chainstay. Looking at it from the side: forward drive has chain shaped shaped like a normal chain. Reverse chain looks like a figure 8.
I should build it, but I have enough unfinished projects and three boys so no time.
[quote=JackD][quote=EivlEvo][quote=JackD]WTF was I thinking of…?
OK, how about chainrings on both sides of the crankset (seen this somewhere)
Flip flop hub so you can have a freewheel on both sides.
The only part I’m not so sure about is the cross-over for the retro side.
Seems like a pair of derailleur pulleys side by side could keep the chain separate when it crosses over itself, but I have no idea of whether this would interfere with the chainstay.[/quote]
Jack what are you trying to accomplish exactly? If you wanted 4 speed you could run a front derailleur easily. You would just need to watch your chain tension.
If you ran cranks on both sides and freewheels on both sides, one would never engage unless you removed the chain from the bigger gear on one side.
Im very confused.[/quote]
Cranks both sides. Chain on one side crosses so that the chain running off the bottom of the chainring pulls directly on top of the freewheel. Somewhere in-between they have to cross… so you just need a guide to keep them from messing with each other and keep them off the chainstay. Looking at it from the side: forward drive has chain shaped shaped like a normal chain. Reverse chain looks like a figure 8.
I should build it, but I have enough unfinished projects and three boys so no time.[/quote]
I thought thats what you were getting at… but what would be the point? Like a sort of opposite retro direct type thing? So 1 freewheel mounted normally on the back, and 2 chainrings (1 on each side) up front?
[quote=EivlEvo][quote=JackD][quote=EivlEvo][quote=JackD]WTF was I thinking of…?
OK, how about chainrings on both sides of the crankset (seen this somewhere)
Flip flop hub so you can have a freewheel on both sides.
The only part I’m not so sure about is the cross-over for the retro side.
Seems like a pair of derailleur pulleys side by side could keep the chain separate when it crosses over itself, but I have no idea of whether this would interfere with the chainstay.[/quote]
Jack what are you trying to accomplish exactly? If you wanted 4 speed you could run a front derailleur easily. You would just need to watch your chain tension.
If you ran cranks on both sides and freewheels on both sides, one would never engage unless you removed the chain from the bigger gear on one side.
Im very confused.[/quote]
Cranks both sides. Chain on one side crosses so that the chain running off the bottom of the chainring pulls directly on top of the freewheel. Somewhere in-between they have to cross… so you just need a guide to keep them from messing with each other and keep them off the chainstay. Looking at it from the side: forward drive has chain shaped shaped like a normal chain. Reverse chain looks like a figure 8.
I should build it, but I have enough unfinished projects and three boys so no time.[/quote]
I thought thats what you were getting at… but what would be the point? Like a sort of opposite retro direct type thing? So 1 freewheel mounted normally on the back, and 2 chainrings (1 on each side) up front?[/quote]
It would still be retro direct. except without the need for reversing spool for the chain. You would have two chains, two chainrings, two freewheels. On the drive side, just like a normal freewheel, on the other side the chain crosses itself so you can pedal in reverse.
I think you may still need a chain tensioner tho… when you change directions, the chain sort of warps (almost like chainsuck). Without good chain tension you may derail often. And I think a chain “tube” (like PVC) is the best solution. It would/could also act like a chainkeeper in the sense that you can very easily position it so that it aligns the chain with the desired ring… but the chainstays may get in the way at some point.
I wouldn’t mind trying this… but now that my RD is at 98% reliability… I’m really apprehensive of messing with it (cuz im a bitch) and don’t want it to not work again = headache x 20 mazillioning
I think you may still need a chain tensioner tho… when you change directions, the chain sort of warps (almost like chainsuck). Without good chain tension you may derail often. And I think a chain “tube” (like PVC) is the best solution. It would/could also act like a chainkeeper in the sense that you can very easily position it so that it aligns the chain with the desired ring… but the chainstays may get in the way at some point.
I wouldn’t mind trying this… but now that my RD is at 98% reliability… I’m really apprehensive of messing with it (cuz im a bitch) and don’t want it to not work again = headache x 20 mazillioning
Edit: fucking sick paint skills dewd.[/quote]
I’m sure it would be a headache. Looked at the chain crossing bit today and there is no good place to do it. I’m considering two idler pulleys mounted just rear of the axle (one above and one below) so that you could keep the chain un-crossed, but instead of having it run round the back of the freewheel, it would drive it on the front side. This approach keeps your chainline absolutely straight and gives you a few pieces of frame to mount to (the frame end, seat and chain stays. You could fabricate a pretty stout bracket to hold the pulleys in place. I’m guessing the pulleys would need to be centered about an inch or so behind the axle so you can get enough of the chain wrapped around the freewheel.
You know Jack… I wonder if the inventor of a retro direct bicycle had sat there thinking of a design more similar to yours and ended up with a design that ended up “being” retro direct. Or if you’re truly braving into lunacy?
hmmmm… the pulley that takes the load needs to be steel and needs to be mounted rock solid, the other one can me just a simple tensioner. Wheel removal would be simplified if one pulley was on the seat stay and the other was out behind the axle with the freewheel being being driven on from the top by the bottom of the loop of chain.
What if you drive off of the back of the ring instead of the front of the freewheel. There are more options up front to mount pulleys to than the back of the bike offers. The solid mounted pulley could attach to the seat tube, the down tube, or a bracket between the two tubes. The tensioner could hang from the front of the chainstay
[quote=agave802003]hmmmm… the pulley that takes the load needs to be steel and needs to be mounted rock solid, the other one can me just a simple tensioner. Wheel removal would be simplified if one pulley was on the seat stay and the other was out behind the axle with the freewheel being being driven on from the top by the bottom of the loop of chain.
What if you drive off of the back of the ring instead of the front of the freewheel. There are more options up front to mount pulleys to than the back of the bike offers. The solid mounted pulley could attach to the seat tube, the down tube, or a bracket between the two tubes. The tensioner could hang from the front of the chainstay[/quote]
Yep… especially if you use a small front chainring. The load bearing pulley could mount on the seat tube and if necessary, brace against the chainstay…
As you say, the other one is just to keep the tension so it doesn’t need to be as stout.
