Shimano Front Freewheels System '70s tech.

[Retrorockit]

1970s Schwin FFS vs. Di2. video.

I did a search here for this and found nothing. Raleigh did some bikes with it but Schwinn and other US builders used it quite a bit.
https://rode-bike.com/shimano-front-freewheel-system/ Some of us are adding this to mid drive Ebikes (which already have the front freewheel) and finding it very useful. You can fake the whole FFS freewheel, with a greased rubber friction ring between the cassette/freewheel and hub flange.

 

[jim haseltine]

I remember Positron rear mechs. They were ok until they started to wear then they were a nightmare - getting hold of and fitting replacement shift cables (more like piano wire) was almost impossible so commuter bikes usually had the mechs and levers replaced with normal friction setups when required. The 'three piece' cranks were actually 4 piece - bb axle (8 lobe if I remember correctly), two crank arms and a separate spider which had the chain rings fitted with a sort of slot and stop method and retained with a couple of small grub screws, one for each ring. The cranks fitted with a self-extracting hex-socket head bolt but were a bit soft where the pedal threads were concerned. A similar design (with the separate spider) was used on a non-FFS chainset - with the right and left cranks being virtually identical other than having L and R marked on the inner face at least one company built bikes with 2 left or 2 right cranks.

 

[Midlife]

The FFS pitched up on a couple of Falcon models, not sure if they were actually listed in the catalogue or if Falcon got a job lot cheap somewhere!

Great in theory.......

 

[Retrorockit]

I would guess the L and R crank arms were just for the lh thread on the lh pedal.
There are still various iterations of this around. Tandems to disengage the stoker, trials bikes use them, and mid drive Ebikes all have them, but few people disable the rear freewheel to take advantage of the shifting (huge on an Ebike). Intend bikes in Germany makes some rather expensive ones for MTB and they're fairly well received. But they use a zip tied cassette which needs to be replaced every now and then. There is a better solution for that.
I ride a Ebike with this every day in urban South Florida. The benefits are a lot more than theoretical. Any gear, any time the bike is moving even if you can't pedal at the moment. Pausing pedaling to shift cuts the power, and saves parts.
Before the age of Mid Drive Ebike kits there were bodgers who needed a freewheel for the big (3kW) electric motors they were fitting. They had cranks made that would accept a HD BMX freewheel and a chain ring adapter. This was usally double. One for the motor to drive, and one to the rear axle.
Some of these can still be found surplus on Ebay and other places.

 

[Retrorockit]

As far as replacing the Positron derailleur the Rapid Rise low normal would still allow the preselect of a downshift when stopped ,a nd Revoshifters were available to allow full use of the front freewheel with SIS indexing at the shifter. I also am using it to this day.

 

[Retrorockit]

I saw one of these at a thrift shop. It was a red 26" 10 speed of a lower specification. Chrome steel rims instead of alloy. But it had the nice metallic red paint job and lots of chrome that Schwinn was known for. Their fillet brazed frames were nice too. I called my local expert and he said it had no value, just an old kids bike. The frame was way too small for me. I might have put some modern BMX red anodized rims, and some Sturmey Archer drum brakes to get away from the rim brakes. I could have done an 8speed Rapid Rise cassette rear driveline and kept the FFS. But I have too many projects already.

 

[Retrorockit]

I've decided to explore this on my street softtail MTB. ( 26"XC bike with slicks). This bike can be seen in the Rapid Rise forum.
I ordered a bunch of surplus parts from various Ebike bodgers, Then found some nicer parts with my existing 104BCD chainring size from a British tandem supplier. SJS Cycles. I'm not doing this because I think it will change the world on a pedal bike (although it is nice for urban riding). It's just that I ride the Ebike with this mod all the time, and it would be nice if they both worked the same way.
One reviewers said the Shun cranks from SJS had a floppy freewheel. I have a heavy duty BMX racing version on the way from the Ebay bodgers. It looks like everyone went to a small 5 bolt flange for this part. I hope they're interchangeable. The US made racing freewheel costs as much as the GB crank arm set.
https://www.sjscycles.co.uk/cranks/...da5d10c0e92e8f03fe&geoc=US&changecurrency=USD The US ISIS Bottom bracket was very wide (159mm), probably to clear some huge electric motor. This one is a more reasonable 134mm and fits my 73mm BB shell. One NOS double chainring with freewheel was $30 from a reputable US vendor. So I should have some spares. The US seems to have settled on 5x110 BCD chain rings.

 

[Retrorockit]

I've looked into the White Industries ENO Ebike surplus front freewheel I ordered on Ebay. It's made for hard use, and all parts are available for service. Definitely not the same as what's inside your typical 5/6/ 7 speed cluster. Normally sold with a built on sprocket(s) for rear use in BMX racing..
https://www.whiteind.com/product/double-freewheels/White does make a trials version of this freewheel (6 pawls) for use in the front, But the range of sprockets is still 18t-22t
https://www.whiteind.com/product/trials-freewheels/But if you require 72 points of engagement it's there.

 

[Retrorockit]

I've got a pile of this stuff now. The cranks and BB from the bodgers ( Sick Bike Parts surplus/ Luna Cyclone double ring set.) was way too heavy to consider for the XC bike. Some of the chain rings were solid steel with no cutouts, just a big metal disc. But the HD White industries freewheel was excellent, and the flat 110BCD adapter puts the single chain ring right in the middle of the single sealed ball bearing. More on this later.
The SJS stoker cranks were very nice, and only about 20g. heavier per arm than the XT Hollowforged Shimanos they're replacing and look about the same too. But the cheap freewheel wasn't sealed and was oozing grease all over the inside of it's plastic bag, so it won't get put on the bike. The 104BCD adapter is very nice, but it's designed for 2 chain rings and they straddle the single bearing. This may work alright if both are driving evenly but may not be ideal for a single chain ring setup. So it's the SJS crank arms and square BB that will be used, with the sealed White Industries racing BMX freewheel ( that can be overhauled), and the flat 110bcd adapter that puts the ring chain ring centered over the bearing.
The English BB threads, and the freewheel threads are the same. The BMX freewheeel didn't thread quite as far down on the crank so I needed a thicker spacer. ABB adjusting ring worked perfectly for this. The chrome one fromSJS looks very nice.
Thorn says these can only be used with an IGH setup. That's because the single sealed ball bearing doesn't like any side load. But on the mid drive Ebikes I've come up with a chain guide made out of recumbent toothed idler parts that feeds the chain straight onto the chainring (like a derailleur pulley) no matter what angle the chain is coming from. This includes lateral or vertical misalignment or play ( useful with a locked rear freewheel). So I want the chain ring centered over the bearing, and the idler/guide will remove any side loads. The actual chainline is not too important when this is used. But it may be pretty good anyway. With this type of guide i also don't need to rely on Wide/Narrow chain rings, or modern clutch type derailleurs to hold things together. This means Rapid Rise is still an option.

 

[Retrorockit]

Here are links to photos of this. There are trials cranks and freewheels out there also. But not all of them are English threaded or 5 bolt pattern. No need to dig up clunky old Schwinn stuff to try this. I'm waiting on 110BCD chain rings from China to do the 1x setup.
https://photos.google.com/direct/AF.../AF1QipPmZTSWVhosyOIiQN0h-0dJ21g7RNNUYfk86OIV
2 photos and a video clip here.
https://photos.google.com/direct/AF1QipNtbpZy2eZ-xvdktnNAj67Mf9lC2HE1_FT1p5ApLYCAbnMCPBkGkRsb_jEJnQlP-w/photo/AF1QipOO8TNTOXK_9d1cUVP7jX4-zSmGBGxcBJtSaDjU