Mid drive front freewheel mod.

Joined
Feb 8, 2019
Messages
304
Location
South FL USA
This mod is so simple, cheap and easy to try, I would like to ask you to try it before posting here.

There have been threads about using the front freewheel that most mid drives have instead of the rear one that bicycles already have. So this would apply mostly to converted bikes with mid drive kits, and not factory made ones.
There were a lot of negative comments mostly fear, panic, and rumors about the chain pulling you off the bike or removing body parts.
So of course I had to try it for myself.
1- Bikes were made in the 1970s with Shimano Front Freewheel System (FFS). So this is actually nothing new. The freewheel was in the crank.
2- They used a special cassette/freewheel with a fiction drive for each cog so it would partially disengage and "coast" to a stop if the chain got caught up in the front.

The functionality of the locked freewheel can be duplicated by simply tying the hub/spokes to the inner cog of the cassette with a nylon wire tie. "Zip Tie" in US terminology. The smallest commonly available ones are 14#/6kg rating. I can put one around my finger and with a pair of pliers break it. So it performs a breakaway function if the chain gets hung up. It doesn't drive the bike it just carries the chain/cassettte around when coasting. I've used 2 at once so far with good results and am going to test with just one. I carry a few spares and some tweezers in my tire repair kit in case I need them.
That is the entire modification. Easily reversible.
I've tested this on a 1500W BBSHD street bike used for intercity cruising. Speeds from 0-32mph. In EU this would be a 50kph pedelec.
This bike does already have a twist shifter, and Rapid Rise low normal derailer installed for better downshifting. Gearing is 50tx11-40t 8 speed on a 26" bike with speed rated balloon tires.
It works great. Upshift or downshift any number of gears as long as the bike is moving. This can be tested/demonstaraed on the center stand any time. The only difference is you stop pedaling to shift. This cuts power, and releases the front freewheel.
if this is hard to learn, a quick back pedal motion works even better.
This produces a conventional Motor-Clutch-Transmission layout like normal cars and motorcycles use. You drive it the same way.
One question that was asked was what about a shift sensor switch?
I had one and took it off the bike before this mod was even considered for 2 reasons based on it's own function.
The fixed delay it provided was too long for fast acceleration in traffic. The fast-slow- fast - slow acceleration confused drivers behind me.
The delay was also too short for multiple gear downshifts when braking from speed, and would send power to the chain when between gears. With a BBSHD that can be lot of power.
With this mod the delay is whatever I need because it's determined by me. The sensor is totally unnecessary.
The other question which remains unanswered is how it works off road. I'm 69 years old and it's flat where I live, so someone else while have to answer that one. Modern clutch type derailers and chain guides may have a lot to do with the results.
This rides very much like an IGH bike. It's better than the Low Normal derailer solution ( although I can still downshift when stopped). The Gripshifter is still a big plus.
The notion that E bikes can only shift one gear at a time is total nonsense. If I throttle the BBSHD I need at least 2 gears up for cadence to catch up.
This mod is so simple, cheap and easy to try, I would like to ask you to try it before posting here.
If you are motorizing your own bike, you are responsible for understanding what you are doing, and the risks involved.
 
I suppose I should add that if you have a coaster brake version of a mid drive it won't have a front freewheel and this would make your bike a fixed gear. The Zip Tie would probably break the first time you applied the brakes anyway. The coaster brake TSDZ2 is almost never mentioned in the US forums, but I know it exists here. If you have one of those don't try this. This is only for bikes that have a front freewheel.
 
But... why? What can it possibly accomplish? You still cannot shift while stationary, I mean.
 
https://endless-sphere.com/forums/viewtopic.php?f=28&t=66263&p=1731630#p1731630

BTW I CAN shift when stopped. But that's a different mod.
To shift when stopped you just get a Shimano Rapid Rise (Low Normal) derailer and matching Revoshifter (gripshift).
Mine is XTR medium cage.
But it is so easy to already be in the right gear with this mod I don't really use it much any more.
Did you ever think about how stupid it is to keep pedaling when you're stopping?

.
 
Retrorockit said:
This mod is so simple, cheap and easy to try, I would like to ask you to try it before posting here.

There have been threads about using the front freewheel that most mid drives have instead of the rear one that bicycles already have. So this would apply mostly to converted bikes with mid drive kits, and not factory made ones.
There were a lot of negative comments mostly fear, panic, and rumors about the chain pulling you off the bike or removing body parts.
So of course I had to try it for myself.
1- Bikes were made in the 1970s with Shimano Front Freewheel System (FFS). So this is actually nothing new. The freewheel was in the crank.
2- They used a special cassette/freewheel with a fiction drive for each cog so it would partially disengage and "coast" to a stop if the chain got caught up in the front.

The functionality of the locked freewheel can be duplicated by simply tying the hub/spokes to the inner cog of the cassette with a nylon wire tie. "Zip Tie" in US terminology. The smallest commonly available ones are 14#/6kg rating. I can put one around my finger and with a pair of pliers break it. So it performs a breakaway function if the chain gets hung up. It doesn't drive the bike it just carries the chain/cassettte around when coasting. I've used 2 at once so far with good results and am going to test with just one. I carry a few spares and some tweezers in my tire repair kit in case I need them.
That is the entire modification. Easily reversible.
I've tested this on a 1500W BBSHD street bike used for intercity cruising. Speeds from 0-32mph. In EU this would be a 50kph pedelec.
This bike does already have a twist shifter, and Rapid Rise low normal derailer installed for better downshifting. Gearing is 50tx11-40t 8 speed on a 26" bike with speed rated balloon tires.
It works great. Upshift or downshift any number of gears as long as the bike is moving. This can be tested/demonstaraed on the center stand any time. The only difference is you stop pedaling to shift. This cuts power, and releases the front freewheel.
if this is hard to learn, a quick back pedal motion works even better.
This produces a conventional Motor-Clutch-Transmission layout like normal cars and motorcycles use. You drive it the same way.
One question that was asked was what about a shift sensor switch?
I had one and took it off the bike before this mod was even considered for 2 reasons based on it's own function.
The fixed delay it provided was too long for fast acceleration in traffic. The fast-slow- fast - slow acceleration confused drivers behind me.
The delay was also too short for multiple gear downshifts when braking from speed, and would send power to the chain when between gears. With a BBSHD that can be lot of power.
With this mod the delay is whatever I need because it's determined by me. The sensor is totally unnecessary.
The other question which remains unanswered is how it works off road. I'm 69 years old and it's flat where I live, so someone else while have to answer that one. Modern clutch type derailers and chain guides may have a lot to do with the results.
This rides very much like an IGH bike. It's better than the Low Normal derailer solution ( although I can still downshift when stopped). The Gripshifter is still a big plus.
The notion that E bikes can only shift one gear at a time is total nonsense. If I throttle the BBSHD I need at least 2 gears up for cadence to catch up.
This mod is so simple, cheap and easy to try, I would like to ask you to try it before posting here.
If you are motorizing your own bike, you are responsible for understanding what you are doing, and the risks involved.

Interesting - I just tried it on one of my TSDZ2 bikes. Takes about 2 mins - i've just put one cable tie for now, tying the largest cog to a spoke. Just rode up and down the road, no apparent issues and yes it's very odd shifting when not pedalling and it all 'just working'.... will see how it goes :)
 
Thanks for actually giving this a try. You're the first one so far.
If one tie works for you I would leave it at that. Less is more for this. I use the small ones and carry a spare or 2.
If you get a chain suck you want it to break and the bike just goes back to normal.
 
I've got another user at electricbike.com to try it. He a has 2500W Luna X2 off road bike. One gear at a time on a 12 speed was kind of tedious for him. He's happy with it so far also.
https://electricbike.com/forum/forum/main-forum/diy-discussion/155141-does-a-mid-drive-really-need-a-freewheel/page3#post155899
 
Thank you for sharing all the things you don't like or don't want to know about. I agree that over about 1500W bicyle parts no longer make much sense. But that's what the user at electricbike has, and on a bike like that this mod. will make a bigger difference than on a TSDZ2.
I spend my time at electricbike.com because the bikes there are more like my own.
I actually know first hand what tire liners can do for a hardtail bike. At 25kph almost nothing, at 50kph a hell of a lot.
I have a thread on that at electricbike with about 350 views in 4 weeks.
 
I started a thread about this mod because the question has been asked in several places but never answered.
Now it has been answered. Anyone who wants to can easily answer it for them selves. It can also be undone even quicker. if they don't like it.
That is choice based on facts and experience, Not opinion based on some mystical "understanding" of some self appointed internet guru.
I spent 50 years as a mechanic fixing things that Chief Engineers got wrong.
I ride my BBSHD 23 miles every day to lunch. That's my shortest ride. I'm retired so i can do that, That;s how I test my mods.
Bikes converted by their owners usually don't have a Chief Engineer anyway.
I'm not impressed at all by the offerings of the commercial E bike vendors. By building to my specific needs I can do better. If I can I will help others do the same.
Did it ever occur to you that your Ducati is keeping you from actually learning more about Ebikes?

I try things on my bike. If they make it better they stay there. If they make it worse they come back off. I didn't invent any of this. So I share it with others, like it was shared with me.Theory without application and testing is just a bunch of hot air.
 
I keep my bike inside the house. I push it around all the time to come and go. The front freewheel works just fine for this.
If it ever was an actual problem you could just have your Chief Engineer cut the zip tie for you.
Then you can push your bike around all you want.
 
argh
 

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Retrorockit said:
Thanks for actually giving this a try. You're the first one so far.
If one tie works for you I would leave it at that. Less is more for this. I use the small ones and carry a spare or 2.
If you get a chain suck you want it to break and the bike just goes back to normal.

Yea so I rode with it for the first time today (other than up and down the street slowly) as I've been away for the weekend - tbh I forgot I'd done the mod. First time I jumped off a dropped kerb (as I do like a child every time I ride off down the street) the chain came off the front chainring and wedged between the motor and the chainring... good thing was the cable tie did the right thing and snapped - and could be a coincidence... my guess it's because 'pushing the chain from the rear' (since the derailleur adds some slack) rather than 'pulling it from the chainring' means it's not got as much tension on the chainring and so more likely to jump....
 
Yea so I rode with it for the first time today (other than up and down the street slowly) as I've been away for the weekend - tbh I forgot I'd done the mod. First time I jumped off a dropped kerb (as I do like a child every time I ride off down the street) the chain came off the front chainring and wedged between the motor and the chainring... good thing was the cable tie did the right thing and snapped - and could be a coincidence... my guess it's because 'pushing the chain from the rear' (since the derailleur adds some slack) rather than 'pulling it from the chainring' means it's not got as much tension on the chainring and so more likely to jump....
[/quote]

Shimano and Schwinn sold bikes with a front freewheel system. The rear cogs had a slip clutch in each one for this eventuality.
But it was so long a go I've never even seen one.

I am already running a front roller chainguide to avoid chain drops so I can't tell if it's more or less likely. There's a user at electricbike.com who rides offroad and is trying this. But he probably has a clutch type derailer. I can't personally try every configuration and situation. So the feedback is useful even if it's not positive so far. But I stopped dropping off curbs for that reason long before this mod. I've got a couple hundred miles on mine and I really like the way it shifts. I hope you'll give it another try to see how it shifts. Maybe it will be worth adding a chain guide as part of this. Mine clamps around the seat post. The other user is happy with it so far.
 
ebuilder said:
beemac said:
Retrorockit said:
Thanks for actually giving this a try. You're the first one so far.
If one tie works for you I would leave it at that. Less is more for this. I use the small ones and carry a spare or 2.
If you get a chain suck you want it to break and the bike just goes back to normal.

Yea so I rode with it for the first time today (other than up and down the street slowly) as I've been away for the weekend - tbh I forgot I'd done the mod. First time I jumped off a dropped kerb (as I do like a child every time I ride off down the street) the chain came off the front chainring and wedged between the motor and the chainring... good thing was the cable tie did the right thing and snapped - and could be a coincidence... my guess it's because 'pushing the chain from the rear' (since the derailleur adds some slack) rather than 'pulling it from the chainring' means it's not got as much tension on the chainring and so more likely to jump....
Whoops, that law of unintended consequences RR never considered

This was totally considered both by me and when Shimano offered it. It's the reason for 1- 14# zip tie. It's going to be up to the user whether it's worth taking steps to prevent chain drops. My bike already has them, so it hasn't been an issue for me.
 
In my own case I was getting chain drops in other situations and this mod has actually made it much better. But I did already take a couple steps to try and prevent them. The top roller guide, and a mid cage derailer. This was before the zip tie mod. Those are both part of my builds now.
One situation was shifting when accelerating or braking through turns. The bike was leaned over perhaps too much to pedal, and cutting the throttle may have created chaos between which freewheel was effecting things. Since this mod I can lean the bike over, give power through the turn and since I'm not pedaling up or downshift as desired. I find this particularly useful at traffic circles.
The other was hard acceleration form a stop. If the bike wasn't fully in gear then the chain could get wound up in things. Now the down shifts are easily completed during braking. So for me it's been a net gain in chain retention.

I'm going to give an example of how vendors, and manufacturers can fail end users. There is a very simple aluminum heat spreader for the TSDZ2 that could be offered for about $10. I contacted a couple sellers of these and they both agreed it looked good. But one of them had already invested in a 55 gallon drum of thermal putty. The other was working on a very expensive water cooled kluge of some kind. It's their job to sell you what they already have. or sell you something they invented. Beyond that you're om your own. The TSDZ2 itself has a chief engineer hiding somewhere.
 
ebuilder said:
Retrorockit said:
In my own case I was getting chain drops in other situations and this mod has actually made it much better. But I did already take a couple steps to try and prevent them. The top roller guide, and a mid cage derailer. This was before the zip tie mod. Those are both part of my builds now.
One situation was shifting when accelerating or braking through turns. The bike was leaned over perhaps too much to pedal, and cutting the throttle may have created chaos between which freewheel was effecting things. Since this mod I can lean the bike over, give power through the turn and since I'm not pedaling up or downshift as desired. I find this particularly useful at traffic circles.
The other was hard acceleration form a stop. If the bike wasn't fully in gear then the chain could get wound up in things. Now the down shifts are easily completed during braking. So for me it's been a net gain in chain retention.

I'm going to give an example of how vendors, and manufacturers can fail end users. There is a very simple aluminum heat spreader for the TSDZ2 that could be offered for about $10. I contacted a couple sellers of these and they both agreed it looked good. But one of them had already invested in a 55 gallon drum of thermal putty. The other was working on a very expensive water cooled kluge of some kind. It's their job to sell you what they already have. or sell you something they invented. Beyond that you're om your own. The TSDZ2 itself has a chief engineer hiding somewhere.
A proper build doesn't need a roller guide or mid cage derailleur. A proper build requires correct chain line and a top quality short/long tooth profile front chain ring. More integrity? Clutch rear derailleur for greater chain preload/tension. On mid drives with single front chainring, 'long cage is preferred' to support overall expanse of gearing. Conflating long cage with chain tension and no chain drops is wrong.

If you think for a minute that the engineers that designed these products didn't consider every permutation including any benefit of a locked up rear freehub and things you wouldn't consider in your wildest imagination, you would be dead wrong. Why such vigilance? Competition and liability. Engineers in fact have a dedicated document addressing design failure interaction. Its called a DFMEA. Its their holy grail of survival. People go through life looking for kluges like zip tied rear cassettes because they don't understand underlying principles.

ebuilder - no one is forcing you to try anything. If you don't like something - just move on. You've made your point but now your constant sniping in this thread is getting pretty tedious... as is the implication that if someone is doing something you don't agree with that they are idiots. Personally I like the idea of being able to shift without pedalling - and so for me this was worth investigating. Unintended consequences are the product of trying things out - if you think you've always considered all outcomes to every problem before testing something - you're wrong...
 
Shimano.
https://www.youtube.com/watch?v=J39t1IxAPcg
Or the zip tie breaks.

To a large extent my wheels, brakes and driveline are old school DH racer parts.
In theory, theory and practice are the same. In practice they are different.
Engineering IS done with very little invention.
 
My setup is probably not typical, and may be better suited for this mod than most builds. A Wide Narrow inset ring can probably tolerate side to side deviation better than mine. But the roller chain guide can probably absorb vertical motions better.

Bell Laboratory in the '60's which was in the business of inventing things found that there was an inverse relation ship between patents granted, and level of education. The more educated knew everything that was already known. Perhaps thinking they knew it all. But the real progress was being made by others.
 
Exactly this...
 

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For anyone who wants to investigate this.
1- The single smalll zip tie will get you in the game, and has a failsafe function.
2- Look at the Shimano FFS videos so you know what to expect.
3- Ease into it. No jumps or dropping off of curbs. See what shifting without pedaling has to offer YOU.
4- A chain guide may be needed. My bike already had one so I didn't consider it part of the mod.But I guess it is.
You might even consider doing that first to get the bugs out.

There are 2 simple chain guides that clamp around the seat tube. Universal Cycles in the US has both. The only difference I see is seat tube size. They are not roller guides. Mine became a roller because I needed to extend it out to my 50t flat chain ring and a roller was easier to fabricate a longer shaft (8mm stainless Allen bolt).
The ProblemSolver "Chain SPY", and the T.H.E " Lll Chap"

I have no experience with Wide/Narrow chain rings with chain guides. So you're on your own there. If it gets 1 tooth off they might not play well together. IDK if that's common or not.

FWIW before I retired I was a Teamsters Union shop steward for 20 years. That won't mean much to non US users. But my motto was "If you want to be a prick, I will give you lessons". I actually find ebuilder attempts at insulting me amusing. Since he has apologized for his tone I will stop tormenting him. I am definitely a bigger asshole than he can imagine.
 
Retrorockit said:
For anyone who wants to investigate this.
1- The single smalll zip tie will get you in the game, and has a failsafe function.
2- Look at the Shimano FFS videos so you know what to expect.
3- Ease into it. No jumps or dropping off of curbs. See what shifting without pedaling has to offer YOU.
4- A chain guide may be needed. My bike already had one so I didn't consider it part of the mod.But I guess it is.
You might even consider doing that first to get the bugs out.

There are 2 simple chain guides that clamp around the seat tube. Universal Cycles in the US has both. The only difference I see is seat tube size. They are not roller guides. Mine became a roller because I needed to extend it out to my 50t flat chain ring and a roller was easier to fabricate a longer shaft (8mm stainless Allen bolt).
The ProblemSolver "Chain SPY", and the T.H.E " Lll Chap"

I have no experience with Wide/Narrow chain rings with chain guides. So you're on your own there. If it gets 1 tooth off they might not play well together. IDK if that's common or not.

FWIW before I retired I was a Teamsters Union shop steward for 20 years. That won't mean much to non US users. But my motto was "If you want to be a prick, I will give you lessons". I actually find ebuilder attempts at insulting me amusing. Since he has apologized for his tone I will stop tormenting him. I am definitely a bigger asshole than he can imagine.

It’s not worth the diatribe. Anyone around ES awhile gets that we don’t need self proclaimed experts to critic innovations.

Many an expert has jumped in and made all sorts of ego centric criticisms trying to dominate threads. They come, and they go. They’re the sort the foe setting can best deal with. Come up with an anonymous name and avatar and make all sorts of claims about their acumen and technical leadership free of any attribution. Not what ES is about.
 
So you know. This is what we see when someone is a “foe”.
 

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The reason I asked for only people to post here who had tried this was not to "force" anyone to do anything, but to avoid having pigs and basketball players all over the place. But it is what it is.



PS I like to build computers too. In 2015 I took a 10 year old Dell Dimension E520 that no one had ever overclocked, and put it in 2nd place at CPUZ for the QX6800 CPU.On aircooling. It's probably still a top 10 score. CPUZ is a worldwide ranking.
 
Retrorockit said:
How many ad hominim attacks have you made on me here?

I don't put playing cards in my spokes because some one might mistake me for you on your DORKcati.
BTW I didn't mention your name, is there some reason you think i meant you?

Its what he does. Not worth reading. Disingenuous and best as a foe.
 
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