Does a mid drive really need a freewheel?

[Retrorockit]

I have a couple donor bikes with mag wheels, and a Nuvinci 171b CVT hub that use the dreaded threaded on freewheel format. With a Bafang mid drive do I even need a freewheel at all? There is a 1 way clutch in the cranks and another at the motor. Maybe it's time to just weld one of those useless suckers solid?

One hidden benefit would be downshifts without pedaling. maybe not at a stop, but better otherwise.

[AZguy]

No reason you need a freewheel at the rear hub, the ring can turn forward freely just as easily as you can pedal without the motor running or the motor turning without pedaling... both BBS clutches will be freewheeling as the ring turns...

[Retrorockit]

I asked Sunrace about their new freewheels for mid drive Ebikes and got blown off. So now it's time for plan B.

[73Eldo]

Shimano had a system like that around 1980 I think called the Positron. Freewheel was on the crank just like a BBS. Last gen of the Schwinn Varsity was one of the models that got it. That system worked OK because all you were trying to spin was the chain ring. In this case I think there may be too much drag and you would end up yanking on the derailleur cage when coasting then it would have to snap back when you went back on it. Having the chain going slack on the top opens up a lot of bad possibilities.

[Retrorockit]

I'm actually having a little of that right now.One bent tooth on one cog plucks the chain when it's on the next gear and then it snaps back.
I may set up one of the mag wheels and give it a try. The Schwalbe tire fiasco has brought that project to halt for now. I do already have a top roller chain guide in place. Maybe that will save me.

[AZguy]

I guess having top chain slack being bad is true but it seems to me that the motor clutches are so low-drag and the rear wheel accelerations also so very low that it's hard for to imagine it being a reality...

YMMV

[73Eldo]

It should be pretty easy to go out and test. IF you don't have a 'dork disk' you should be able to just run a small zip tie through a slot in the large cog and tie it to a spoke.

[Retrorockit]

Not sure what a "Dork Disc" is, but I think I want one! I have some stainless steel zip ties that are probably up to the task. I'm seeing a big upside to this as far as multigear downshifts when braking goes. If I put the zip ties at a trailing angle from the spokes it should work well.
My olde XT hubs actually have some cutouts in the spoke flanges I can use. I'm already running Rapid Rise stuff so the difference may not be as obvious to me. So if someone else wants to play along it might be useful.
Thanks for that tip. I won't have to create a mag wheelset try this idea. I need a new cassette right now anyway so I'll give this a try.

[Retrorockit]

There might be another hidden benefit to this. I tried the shift sensor, but got rid of it because acceleration sufffered. But now w ith the 24Ah battery, and Tannus liner in the rear I'm riding faster and at higher power settings than before. I tried the stop pedaling power cut method, but this also delayed the shift until power came back on because the cassette stopped too. This may allow me to cut power but have the shift completed at the same time.

[Retrorockit]

I did the mod. First try with the stainless steel zip ties didn't work. They won't twist enough, and won't pull through if they aren't straight. So after cutting a 1/2 dozen of them out of the hub with a cable housing tool, I went with 3 plastic zip ties. They have to go in near the hub so they don't bump the chain on the smaller cogs. But they went through 3x holes in the XT flange, through 3 inner cog holes, and over the flange. I can get 3 more in there if needed. But they aren't just tied to the spokes. I can report that the front freewheel is almost as loose as the rear. Spin the rear wheel with the bike upside down and it keeps turning with the pedals stopped, and the chainring still going. I'll report back after a test ride.

[Retrorockit]

I did the test ride, about 30 miles. This is a very nice mod. Absolutely no problems found and I can make a smooth silent shift up or down any time the bike is moving. Real time smooth shifts. Stopping the pedals with the driveline still moving works great. It can be a little hard to know if you actually stopped, but the old Bendix 2 speed kick back works great (really showing my age here).
Thanx 73 Eldo for the zip tie idea. Looping it though the hub instead of just the spokes means it won't migrate into the chain area. Rapid Rise still lets me shift when stopped, but that won't be needed very often with this setup. RR pulling cable for upshifts is still real solid under power. I'm going to calls this the "BBSHD Fixie Mod". I didn't think there was anything else I could do to this bike......

[73Eldo]

Ahhh the Bendix 2 speeds. When I worked in a shop in the 80's they would still come in for repair from time to time so I got to work on and test ride them occasionally. I don't remember if we could still order the parts at that time or if we just had em as NOS since our shop had been around a long time.

I remember one that the customer would bring in every year for service because the guy would ride like 1000 miles per season. It was a unique bike, it was one of the hand built Paramount frames that I'm sure would have originally came with Campy stuff on it but he had turned it into a custom touring bike sort of thing, It did ride really nice, for the era was a very lightweight and streamline bike with no cables since it had the coaster brake and no shifting. Guy was ahead of his time, if he was around now days he may be a single or fixie guy. I think he was in his 70's when I knew him.

I thought they were really cool and were a major improvement over a single speed but not as 'complex' to operate as a 3 speed. There were different gearing from what I remember you could identify by the color bands on the hub. I think you could get overdrive or under drive. I tried to put one on a commuter bike but it wasn't the right one so it made for a pretty crappy ride. There is a slight chance its still in a box somewhere, I remember pulling it out and reusing the rim it was on.

[73Eldo]

Interesting to hear your results. I may give it a try just to see if it works for me too and if I have any impression of things being different for better or worse. If nothing else it should remind me of riding my Varsity 40 years ago. I'm pretty sure those still had a freewheel of sorts in the back because I remember using my foot to jam up the chain ring to make the chain go slack. I wonder how many nylon ties you would need to make it reliable but still break loose if needed? Just thinking of the time I got my pants leg stuck in the chain ring... Now that I think about it that may also be how I discovered that my Varsity had a rear freewheel too.

[Retrorockit]

The derailer cage is still there as a relief for too much tension. Since I'm running a Gripshift/ Rapid Rise I can say that this might be better than Rapid Rise. I can drop a bunch of gears w/o pedaling and the shift is done already. No need to pedal it into gear. With a Gripshift it's pretty much dialomatic shifting. There were 6 holes in the XT hub, and 6 holes in the spokes of the inner cog. But after the battle with the stainless zip ties I just used 3 regular ones. You really need to keep up with bicycle fashion. A pair of pant with one long and one short leg is the way to go now. Shows off the grease stain on your right calf to prove you're the real deal.

[Retrorockit]

Here's the Shimano version.

https://www.youtube.com/watch?v=Dwpnxh_Vxpk

[73Eldo]

Mine was Positron II. Index shifting from 1976.

https://www.shimano.com/en/100th/history/products/16.php

I think mine was an 82 Deluxe Varsity, sky blue. I could be wrong about the year but it was around there. I had forgotten about the Deluxe part till just now but I remember making a point bragging that mine was Deluxe.

https://bikehistory.org/bikes/varsity/#1982-varsity

I think it may have been some sort of law that if you were between 10 and 18 years old between 1951 and 1986 that your first non 20" wheel bike had to be a Schwinn Varsity. Or was that just in my area? The blue Huffy Omni 10 speed was was also popular if you didn't have the big bucks to buy a low end Schwinn.

[Retrorockit]

I had a metallic green Scwhinn Collegiate 1x5 bike that was absolutely beautifu with stainless fendersl, and a silver 2x5 Scwinn Letour (not hardly LOL) that had steel rims because I didn't like the gold color of the alloy rim version. Both got stolen her in South FL. But good reliable bikes at a good price.

[73Eldo]

They did a special remake of the Collegiate for only $1000. They did OK on capturing a lot of the look of the original but the chain ring / chain guard is the first thing that doesn't look right to my eye then the black derailleur, you would think someone makes a polished aluminum one. I just flipped through some online photos and it looks like it always had a full chain guard. I wonder why they didn't bother? You see them on plenty of cruiser types of bikes so someone clearly makes them still.

https://www.schwinnbikes.com/pages/collegiate

[Retrorockit]

Nobody really knew much about bicycles back then. Schwinn was respected. But if you wanted your "English racer" to actually be English then you went with Raleigh. I thought Raleighs looked boring. Schwinn made some flashy looking bikes the worked well.

[Retrorockit]

I got another mid range ride in today on the front freewheel setup. This is way different than before. My bike always banged each shift. The higher the assist the harder it banged. Now I have smooth silent shifts all the time as long as I pause the pedals. This has got to be good for chain and cssette life. Even if I wasn't in a hurry it would bang each shift. especially going into headwinds at level 3/5. Now it's smooth as silk. Absolutely no sign of chain being pushed forward from the rear. Of course the chain and cassette are new, and the BBSHD was just lubed and new one way clutch installed so time will tell. But so far so good.

[Retrorockit]

Thinking about how this works I realized that cars, trucks, and motorcycles all have the engine, then the clutch, and then the transmission that is turning with the wheels. I think bicycles ended up the "wrong way" because they inherited the freewheel from single speed bikes, and just built on that. So this is the same as driving a stickshift car. Cut the power, and release the clutch, then shift.
When you stop the pedals on a mid drive you've done this. Exactly the opposite of the bicycle "pedal when shifting" method. Pedal when shifting with a BBSHD in the higher power modes is pretty brutal. I took the shift sensor off of my bike so IDK how it would work with this mod. But I did trash my whole driveline shortly after taking it off.

I apologize to any young people reading this thread. Just the mention of Scwinn sends all of us old geezers traipsing down memory lane. Once upon a time they made good bikes.