frameteam2003

Waiting for parts to arrive for a fixed gear I'm building,I got to playing around with rear hubs,freewheels and BB cups.Finaly figured out how to add two freewheels to the same side of the hub using a spair BB cup.So my next kustom just might be a Hirondelle Schwinn 2speed cruzer.2freewheels,one chain,two speeds,no shifter!Pedals rotate forward for high gear--pedals rotate backward for low gear.

FlatTop

Very cool. For those who can't visualize any better than I can, here's an old Hirondelle setup: https://www.m-gineering.nl/retrog.htm

and a new version:
https://members.westnet.com.au/rjharr...ro-Direct2.htm

wearyourtruth

that's awesome... the things people think of...

MacG

Can you provide some more details on how to get two separate freewheels next to eachother on one hub? I recall hearing about how bottom brackets use the same threading as freewheels/cogs, but I haven't had that type of bottom bracket apart yet. Do you need to shorten the threading on the hub at all, or are there enough left-over threads on the inner freewheel to attach the bottom bracket piece?

Here's a better question: Where would you go about getting a larger-than-usual freewheel? Everything that I have seen for sale is usually less than 20 teeth. I want to find something more like 30 teeth or more. Can freewheels be disassembled and have larger sprockets installed in place of the typical 14 or 16 tooth sprocket?

FlatTop

Harris sells a double freewheel, but they go the same direction, and that won't work, right?

frameteam2003

I'm building one at present.I tryed taking the freewheel apart and brazing on a 24 tooth sprocket---got it to work but not as well as I'd like.The heat warped the freewheel some so it drags a little.I've been hunting around and bikeparts wairhouse has a 22 tooth sprocket and 16 tooth so I'll have to order some to build this kustom(schwinn frame).A regular 5/6 speed rear hub will work as for the spacing--screw on the big freewheel then screw a BB cup into the treads left on the freewheel and screw the second freewheel onto the BB cup---I plan on using a third freewheel minus the paws for the ideler.

MacG

Nope; you need two separate ratchets to make it work.

The freewheels both will have their ratchets oriented for operation in the same direction of rotation, but when one cog is being 'used', the other cog needs to be spinning backwards rapidly. If the cogs were locked together on a single ratchet (like the double freewheel you mention), the bike would be able to coast, but the pedals would be locked solidly in place in addition to the bike being unable to roll backwards.

I dug an old Schwinn "Le Tour III" road frame out of the small bike boneyard beside my house and did some work on it last night in preparation for attempting to build one of these contraptions. In doing so, I disassembled and repacked the bottom bracket. I definitely see how the bottom bracket cup can be used to stack two freewheels now. I even have one freewheel suitable for the high gear scavenged off of an old bmx wheel.

I looked around to find a freewheel with a large cog, but the largest they get is into the 20s of teeth. I want more like 30 teeth, which appears to not exist. I do have a plan, however. 30ish-tooth cogs can be had by disassembling an old multi-gear freewheel. The only problem might be that these sprockets are designed to allow the chain to jump off of the teeth relatively easily, which is an undesirable quality in a transmission that is not supposed to shift gears in this manner. This aside, these cogs are almost exactly the right size to slide on over the outside of a freewheel, requiring just a little grinding to remove the four stubs and enlarge the hole by about 1/8".

FlatTop

The multispeed cogs ought to work, I think. My thought being that you will take care to create a near-perfect chainline, and that the Hirondelle setup provides a greater degree of "chain wrap" around the cogs, keeping it trapped to some degree.

Since you Hirondelle re-creators are working on Schwinns, I'll address this question to both of you: How much will you need to modify the frames? Will it be a minor massaging of the chainstay, or a heat-with-a-torch, put in a zigzag and reshape deal?

frameteam2003

With mine I'm using freewheels that will use 10 speed chain(3/32) not the 1/8 chain used for a standard bikes---this chain is more flexable.If you start with a ballooner frame you might get by with no mods--I'm using a middleweight frame and want to use a 2&1/4" tire so will have to widen the rear some for the tire.I also plan on brazing on the return sprocket,but this could just as ez be done with a bolt on.BTW a breese 10 speed front sprocket works good to,as it's a thin clover leaf made for the 3/32 chain.

MacG

I can guarantee that a two-speed freewheel where the two cogs are locked together will not work. In order for the chain to move, the two rear cogs need to turn opposite directions, which eliminates the possibility of a two-cog freewheel doing the job. THis happens because the chain goes diagonally from the bottom of the front chainwheel to the top of one of the rear cogs.

With regards to chainstay modification, I think I'll slice a chunk out of it and reinforce it with some scrap steel. I had to do a similar modification to the (former) chainstay on the first tallbike I built because the (now vertical) slack side of the chain would hit the (former) chainstay before it made it out to the highest gear on the freewheel.

The method the guy linked above used to fix his chainstay looks pretty good except that I think it could add more flex than would be desired. I'll probably try to come up with something that keeps the columnular strength of the stay as close to how it's supposed to be as possible.

frameteam2003

O.K.--I ordered a freewheel designed for an elect. scooter ---looked like the same threads as a regular bike hub.The scooter freewheel has flanges to bolt on the sprocket,this may give me a large28 or36 tooth low gear---if the treads are the same---will let you know when it arrives---sam

frameteam2003

The scooter freewheel arrived today---same treads,so will be able to simply bolt on any size sprocket I need.
https://cgi.ebay.com/ws/eBayISAPI.dll...MEWN%3AIT&rd=1
this isthe ebay link to show a pic of the scotter freewheel---sam

Noah Scape

I know this is not the same, but it uses the reverse pedaling concept. In this tallbike build, the guy used a stoker tandem crankset with chain running to both wheels – upper wheel runs to the left (larger) chainring and the right small ring runs the bottom wheel. When you pedal forward you are driving the bottom wheel and the top wheel is freewheeling. When you pedal backward, you drive the top wheel. The tires fit snuggly together. So much so that when you pedal backwards, you feel a dramatic boost of power/speed!

frameteam2003

Noah,that's a very cool idea---lots of thought went into that one.
Today I built up the hirondelle.Got it to work(wheel will spin/no riddin yet) but still will need a lot of work.That's the hard part of a kuston---we gotta build everything from scratch and make it work,not just bolt together a pile of parts---but that's the fun---sam ps--I did have to widen the frame to get the chain to clear---not hard just some work with a jack & clamps

zealanderthal

Can't wait to see a picture!

FlatTop

Hirondelle/retrodirect followers: There is a similar post on this subject on another forum:
https://www.bikeforums.net/bicycle-mechanics/144590-2-speed-shifter-less-bike-experiment.html
A few different twists in this project.

frameteam2003

check out the new post under bicycle mechanics title : Retro-Direct Drive. I think we've started something!---sam

FlatTop

You mean, Hirondelles and retro-direct drive bicycles are gonna be the fixies of the 2005-2010 era?
You guys truly have your fingers on the pulse

MacG

Success!

I got the last pieces put together and was able to test drive the contraption late last night. Everything works pretty well so far; I've ridden it around the neighborhood a few times, testing out the low gear on the uphills and the high gear on the downhills. I need to build a means to shift the chain between the two front chainrings and it will be nearly ready for it's first commute.











Here are the gear combinations and corresponding gear inches that can be achieved with my configuration:
42/32 = 35.4in (pedal backwards with small ring)
42/16 = 70.9in (pedal forwards with small ring)
52/32 = 43.9in (pedal backwards with big ring)
52/16 = 87.8in (pedal forwards with big ring)

It's amusing to note that everything on this bike came out of a scrap steel dumpster (and not all in one piece or trip) with the exception of one of the freewheels (BMX bikes are surprisingly rare there) and the bottom bracket cup used to build the rear hub (because I didn't have one laying around that wasn't already attached to a bottom bracket). The first things to be replaced with new parts will be the 16t dumpster freewheel because it is worn enough to jump under heavy pedaling, the tires because the back one has leporasy or something, and probably the chain, since dumpster chain can be like a continuous game of russian roulette.

For shifting the front chainrings, I'm torn as to whether I should just bolt on a standard front derailer or if I sould try to create a device as seen on an original Hirondelle (linked earlier in thread) that works like a derailer split in half so that you are able to shift from the smaller to the larger ring when pedaling forwards, and from the larger to the smaller when pedaling backwards. I guess the theory is that when you want a lower gear, you will probably already be pedaling backwards, so why waste time changing directions twice just to be able to get to your granny gear. Any multispeed biker knows how much of a pain it is to shift from a large chainring to a smaller one while barely creeping along as an unexpected hill appears. Take that sensation and add to it the necessity to stop pedaling, pedal the other way through the shift, and then begin pedaling the way you were before again. It would be doable, but I think the original style shifting system would be that much cooler, if I could get it to work, and it would make shifting while ladeping up hills that much easier.

On a related note, I've pondered ways to add derailers to a traditional multispeed bike to allow it to be shifted at a standstill or low speed by pedaling backwards, and haven't come up with any bright ideas yet. The problem is always that during the shift, the chain is centered on two different sprockets, which means that any shifting system able to accomodate that without binding up would either need to be able to intelligently (mechanically somehow) be able to track with the chain, or have enough slop in it that it would suck to use.

MacG

This evening I accomplished some more work. I replaced the dumpster chain with some new hyperglide I had stocked up for a rainy day and also put a new schimano 17t freewheel in place of the 16t dumpster freewheel that was jumping quite a bit under heavy load. The drivetrain feels much nicer now, and I guess the next step there is to fix the tensioner up with a proper spring and make it more compact.

I found an interesting (and theoretically entirely predictable) new problem that I don't recall reading about anywhere else yet. As I was savoring the smoothness of the new chain by turning the pedals slowly by hand with the bike suspended, I noticed that the right pedal was loose. ...and so was the left!

Back in the ancient history of bicycles, some brilliant person decided that the left pedal should have a lefthand thread because it kept falling off due to precession, where something being turned inside of another thing will turn backwards due to rolling along on the edges. (Wow; that was a terrible description...) Anyways, if you don't understand why left pedals need a lefthand thread, try reading this.

Because of all the backwards pedaling going on, my pedals managed to loosen themselves to the point of being slightly wobbly. I doubt that they were tightened on terribly well when I put the frame together, but just the same, it would be a bit unnerving and also a bit dangerous if one of my pedals simply fell off while spinning backwards up a hill in traffic, so I need to do something about this.

I've read a bit about homebrew tandems having similar problems because the builder used a normal crank for the (left side) linking chain's pedals. I think some blue loktite or perhaps just cleaning all of the grease and oil residue off of the pedal threads and crank holes and reassembling with excessive torque may keep them put. Anyone else that has a rideable retro-geared bike encounter this yet? (all two of you or so...)

frameteam2003

O.K. come clean---where'd you get that big rear freewheel! I see you also did some mods to the rear stay.So far it's just you,Pierre,and me building these.Pierre used two chains with out modifing the stays and mine will be a lot like yours(one chain),only built on a cruzer frame.Check out Pierre's page: https://users.skynet.be/ppc/retrodirect_drive/
sam---PS those left pedals with left threads were a Wright Bros invention.

ppc

Hmm yes, I didn't think about that, but you're quite right, the pedals can indeed work themselves loose with a retro-direct bike. It hasn't happened to me because I don't ride backward a whole lot (just to get up the hill to and from work, and to accelerate) and because I have nature's very own thread locking glue in my crank holes: rust

MacG

I cheated. The big one is actually a pretty standard 16t BMX freewheel the LBS had in their used junk bucket for $5. I have a handful of multispeed dumpster freewheels laying around, and upon disassembling a few with my shiny new homebrew chainwhips (yay!), found that the splined sprockets from one particularly odd-looking 5 speed freewheel was almost exactly the right size to slide over the outside of the BMX freewheel's body. The best part was that to get it to fit, I just had to grind a hair off of each of the three spline teeth on the inside hole. This allowed me to get a darn near perfect sliding fit. To attach it, I used 3/8" bolts through the holes that already existed in the 32t sprocket. Two bolts hold the larger sprocket onto the freewheel's teeth with oversize washers, and the other two provide anchoring against rotation by locking carefully sized washers into the gaps between teeth on the freewheel. This mechanism is heavy and ugly, but it works for the time being. The same method could be used but without the heavy bolts by tack welding the larger sprocket onto the freewheel's teeth. I originally planned to do this, but I was afraid of how the bearing races and lubrication would react to the heat and had no way to disassemble the freewheel to perform the welding.
I thought that might be the case! Gotta love those Wright Brothers!
I must try some! Is it expensive?

I took the bike out this morning for a quarter mile or so (it's cold out!) and the new chain and freewheel are much smoother and the jumping is gone.

Here's a link I haven't seen passed around in this thread yet: https://www.frankb.us/gears/
I like his design for a tensioner more than I like mine. I think I'll adapt mine to be more like that.

ppc

Ditch the front derailleur and you won't need a tensioner, just a fixed idler

MacG

Here are some graphics I put together using AutoCAD to show how the Hirondelle-style retro-direct works.

-----

This is the basic setup. The sprockets on the right are the front chainring cluster attached rigidly to the pedals and bottom bracket. There happen to be two for reasons of even more gears, but this exercise would work just fine with only one gear. The sprockets on the left are on the rear wheel, and each is attached to it's own indepenent ratcheting freewheel. Both ratchet in a manner that is capable of driving the bike forwards and freewheeling for coasting. This is set up just like a single speed bike, but there are two freewheels stacked next to eachother. The small sprocket in the lower middle is a tensioner with a spring on it to keep the chain taut.



When the chain is added, it is routed like this. These diagrams are for a single-chain Hirondelle-type setup, which is not exactly what ppc is doing, but both achieve precisely the same functionality in the end. Note that the chain crosses up from underneath the front chainring to pass over the top of the larger rear freewheel.



This diagram shows only the chain that is tensioned when the pedals are being turned forwards, which provides the high gear. The 52-tooth chainring (turning forwards) is turning the 16-tooth freewheel forwards. The rest of the chain goes around the idler and turns the other freewheel backwards on it's way back around, having no effect on the force applied to the wheel (and making a nice clicking noise).



This diagram shows only the chain that is tensioned when the pedals are being turned backwards, which provides the low gear. The 52-tooth chainring (turning backwards) is turning the 32-tooth freewheel forwards. Note the crossing of the chain, which is what allows the backwards rotation of the pedals to produce a forward motion of the bike. The rest of the chain goes around the tensioner and turns the other freewheel backwards, having no effect on the force applied to the wheel.