Design a Freewheel Crankset for Direct Mount Crankests

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Looking into Mid-Drives I see that the only option for a freewheel crankset currently available as I write this is the old fashion square taper bb or IS design .

However ...

Many of the bikes available now have , and more in the future will have Direct Mount Cranksets.

Evidently the BMX people are wondering why it has taken the 26 inch through 700c/29er bikes so long , to start using this three piece design since there are advantages.

Since most Good bikes in the future will have the Shimano Hollowtec II 2 piece design or what is looking like more likely , most will have 3 piece design / aka / Direct Mount Cranksets ,

Now is the time to design a freewheeling Crankset using the Direct Mount system.

The two people here in the U.S. who are doing the custom larger mid-drives do not know at this time how to design one, and the other person who is making a mid-drive here has said months ago he is looking into using Direct Mount Cranksets on his mid-drive , SamD ... but he has gone silent for a few months now, so I don't know, I question if he will ever get a Mid-drive available .

So I put forth here now, a Goal of getting the World Wide Members of Endless Sphere to come together and submit their design and Ideas.

With enough of us working on this we can come up with the solution .
 
Who can design a way to use the freewheel that is on the heavy square taper bb / square taper bb style cranksets, ... with the newer style direct mount cranksets ?
Direct Mount Cranksets are 3 piece, consisting of two crank arms , and a spindle .
See FSA, Sram, etc.
 
ScooterMan101 said:
Who can design a way to use the freewheel that is on the heavy square taper bb / square taper bb style cranksets, ... with the newer style direct mount cranksets ?
Direct Mount Cranksets are 3 piece, consisting of two crank arms , and a spindle .
See FSA, Sram, etc.

Shoot some pics and diagrams/ideas my way, I have some CAD skills. As long as I have exact measurements and diagrams I can draw up designs.
 
12-C

I have a picture of a Tiagra Road Shimano Hollowtec II 3 chainring crankset,
and
A Deore Mountain Shimano Hollowtec II 3 chainring crankset.

The Idea I have is to do this on a 3 x crankset, that way the inner chainring can be removed and the freewheel put in its place / in the space between the large chainring and the small chainring.

I am not sure how wide the current freewheels are .

The Space available on the Mountain Crankset is 10 mm to work with, or 12 mm if a new outter chainring is made which is flat.

The Space Available on the Road Crankset is 11mm for space for a freewheel if keeping the stock outer chainring, but if a custom made chainring is made that is flat then apx. 12 mm for the entire width for the freewheel.

Anyone have a freewheel that can measure the width of it ?

The outer chainring on both cranksets are dished, I am guessing so as to help with changing from the middle and outer chainring.

I am sure that a new outer chainring would have to be made anyway so as to have larger amount of teeth , so that there is less reduction needed from the mid drive to the crankset . ( chain from motor to crankset on the outer chainring position )

Both have the outer chainring mounted to the crank arm, the Mountain and Road have different BCD's , I can get that latter to you if you need.

So to do this I am guessing that all three chainrings need to be removed, a special spider made to hold the outer chainring and the freewheel, and another spider made to hold the inner chainring to the freewheel.

If you did not know the Shimano Hollowtec II system is a 2 piece crankset, meaning that the drive side also is connected to the spindle , 24mm OD, that goes through the bike to the other side where the other crank arm bolts up to it.
 

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Is this what you are going for?
510BE367-2723-4BD0-85E0-B53FCC479122.jpeg

If so it requires machining this area into threads for the freewheel.
4E9C06BA-4214-4E6D-8BDD-5E72C6524F67.jpeg

Its covered here.
https://endless-sphere.com/forums/viewtopic.php?f=28&t=47765&start=25
 
That looks good .... but
The picture looks like there are still 3 chainrings , and that the chain from the front mid-drive motor is going into the inner chainring . ( would it not be better to reverse that for 2 reasons ? )

Is it a item that can be bought ?

Is there a way to just use the bolt holes for the chainrings to make a freewheel that would not have to have the spindle machined ? , since most of us do not have a machine shop .
 
ScooterMan101 said:
That looks good .... but
The picture looks like there are still 3 chainrings , and that the chain from the front mid-drive motor is going into the inner chainring . ( would it not be better to reverse that for 2 reasons ? )

Is it a item that can be bought ?

Is there a way to just use the bolt holes for the chainrings to make a freewheel that would not have to have the spindle machined ? , since most of us do not have a machine shop .

Not my setup. Here is the original forum.
https://www.pedelecforum.de/forum/index.php?threads/noch-ein-fully-mit-kurbelantrieb.4194/

I too would rather have the motor driven sprocket on the outside because that is usually the biggest and typically these setups need the reduction of a large motor driven sprocket.

This is not something that can be bought. Threading that crank with the rest of the arm whipping around would be a bit scary in a lathe but not unmanageable. Still quite a bit of special setup on that job and wouldn't be cheap to have done. Also, I believe only the multi chainring cranks have enough meat there to machine into threads. I have some hollowtech 2 single ring cranks on my bike and it doesn't look like there is enough there for freewheel threads.

The problem with using the chainring threads to attach a freewheel is that these external bearing Bottom brackets have the outboard bearing housing taking up a lot of real estate. The standard internal bearing BBs like the cyclone kit ones can be used with a longer spindle and give you back the room that you would lose with an external type.

One good thing about Hollowtechs is that you can run an 83mm length spindle with a 73mm BB frame. This gives you 10mm of side adjustment you can work with but will slightly throw off your side to side body positioning.

One bad thing about the Hollowtechs is that they have a 24mm spindle and I've only seen 25mm Id bearings available. The stock hollowtech seems to have a plastic insert in the bearing that takes up the slop between spindle and bearing. Seems strange to me but I trusted them.
 
The External Bearings are 44 mm OD, and 11-14 mm wide . ( Non Drive side is 11 mm but the drive side bearing looks to be 2 mm wider )

Anyway the bearings fit inside of the crank / spyder / inner chainring.

So there is enough space there , on my Mountain Shimano Hollowtec II crankset the space between the inner area where the innerchainring bolts bolt the smallest chainring is at least 50 mm, more like 52 mm to the threads.

So there is really at least 6 mm of space there , ( 3mm on each side/ all around , between the outer material of the bearing and the BCD / inner chainring bolts ) enough for a freewheel to be made to fit over the Bearings , and still connect the inner chainring mounting bolts,
and even more doable if the freewheel is made to bolt up to the outer chainring mounting bolts


DanGT86 said:
The problem with using the chainring threads to attach a freewheel is that these external bearing Bottom brackets have the outboard bearing housing taking up a lot of real estate. The standard internal bearing BBs like the cyclone kit ones can be used with a longer spindle and give you back the room that you would lose with an external type.
 
I took some measurements. It looks doable but at least on a 73mm it would require some fancy machining of the threaded FW adapter. It would need to look like a spider. On a 68mm BB frame this might be possible with a simple round adapter that attaches to the small chainring circle (64mm?)
Here is what I found on mine:
HT crank measurements.jpg

I'm thinking its not really worth it because the current ISIS options on the market using trials cranks seem to be holding up just fine.

Another alternative would be BMX cranks and spindles. I really like how simple the 3 piece crank designs are and you can buy all the parts separately to get whatever spindle length you need.
fsa-bmx-34.jpg
 
This might solve a bunch of problems. Description says it uses hollowtech style cups. It has Shimano style Freewheel splines on the crank and uses a shimano splined freewheel. This could actually be the product many people have been waiting for. I remember years ago there were people broaching WI freewheels to get them to fit on shimano spline cassettes. Freewheel is 17mm wide and the description says the splines are 21mm long.
large_bonzcrankset3 dan.jpg
large_bonz108splined__size-800-0.jpg

here is the link to the seller where I lifted the pics:
https://www.tartybikes.co.uk/cranksets/bonz_3d_forged_crankset/c11p13225.html?pos=200&search_params=YTo3OntzOjEyOiJjYXRlZ29yeV9pZHMiO2E6MTp7aTowO3M6MjoiMTEiO31zOjE2OiJjYXRlZ29yeV9yZWN1cnNlIjtiOjE7czo4OiJrZXl3b3JkcyI7czowOiIiO3M6OToiYnJhbmRfaWRzIjtOO3M6NDoibW9kZSI7czozOiJhbGwiO3M6NDoic29ydCI7czo5OiJwcmljZV9hc2MiO3M6MTA6ImNvdW50cnlfaWQiO3M6MzoiMjMxIjt9
 
The $ 399 price kills is for a contender, and that is not including the chainrings or a freewheel .

The whole Idea for making a bolt on freewheel for Direct Mount ( like the much more affordable Race Face Cinch Cranks)
or
The Shimano Hollowtec II cranksets , is to have a low cost conversion to freewheel crank.
With a lower cost freewheel than the White Industries one , even a custom made , bolt on version could be $ 100 or so.

I think a whole re-designed freewheel to bolt onto the common BCD's is the way to do it. Once designed it could be made in Taiwan or China.


12-C said:
What about http://boxcomponents.com/vector-m30-p-crankset_2
 
DanGT86 said:
Another alternative would be BMX cranks and spindles. I really like how simple the 3 piece crank designs are and you can buy all the parts separately to get whatever spindle length you need.
That's what I was thinking. Put a threaded freewheel adapter inboard of the drive side crank with a Woodruff key to hold it.

It doesn't address the problem of freewheels barfing their guts out when you overrun them with motor power while not pedaling, but at least it's a simple implementation.

Another alternative is use a normal crank, gear the motor drive to match a normal pedal cadence, and develop a doggone backbone.
 
Chalo said:
It doesn't address the problem of freewheels barfing their guts out when you overrun them with motor power while not pedaling, but at least it's a simple implementation.
I would echo these sentiments regarding the freewheel. The lateral loads kill em. Imo the limited space for it all would exacerbate the problem even more and still necessitate the need for the ultra HD freewheel from sbp... The direct drive chain rings only exist because 1x setups became a thing. This they only really need about 4mm for the chain ring and a few more for a non laterally loaded retainer ring.
 
Definitely need either a support bearing for the WI ENO freewheels or the dual bearing HD unit from SBP which is a bit wider I think.

I thought up another possible solution but it again requires machining a few parts. I think the spider adapter that bolts to the Flanged freewheel could have a bearing in it that hangs over the external BB bearing cup. The cup would need to be turned or remade to a size that a bearing could be installed on it. Basically use the bearing cup outside diameter as the support bearing location to eliminate the side load while freewheeling issue. This would be the best way to reclaim some of the real estate lost due to the external BB cups being 10+mm wide. Still hard to stuff in a hollowtech though.
 
A technical approach to the width issue could be the way I made a rear hub for my own bike, so that I could install an axle that was too big to fit through a bearing that would fit inside a freewheel thread.

On the freewheel side, I installed a thin section needle roller bearing. On the left side, I pressed in a large conventional cartridge bearing. Because the axial retention of the hub axle was only in one direction at that point, I made a ring to capture the cartridge bearing on the outside of the hub. Mine was bolted with a 6 hole pattern, but it could just as easily have been an ID snap ring.

Even though I used this layout to get a smaller OD right side bearing, in a bottom bracket it would work to move the right side bearing inside the shell and reduce the width of the assembly.

51PwmPuEmrL._SX342_.jpg
 
Thats good thinking to move the right side bearing into the shell using a super thin bearing like that. Unfortunately the shimano hollowtech spindle is actually machined on the ends where it rides on the bearings. The middle of the undercut has a slightly rough texture that's not concentric with the machined journals. Looks like its forged rough like a slight hourglass shape with extra material in the bearing area. They must just take a small cleanup pass with a lathe to get it to spec. It was very subtle but about .005-.010" smaller in the middle which is a mile when you are talking bearings.

I had to measure it because I am using an 83mm length spindle with a 73mm BB. I was worried it would miss that part when I noticed it was varying diameters. Thin wall bearing inboard might still be manageable with a sleeve pressed over the spindle and some epoxy to fill the slight void under the sleeve if the bearing needed to ride on that part. I can measure mine next time I take it apart to see if the bearing section is long enough. I just don't have a whole lot of motivation to remove it because I don't actually even need a freewheeling bottom bracket for my stuff. I'm just a machinist who finds it interesting.

This is what I was thinking for the FW support bearing installed on the outboard bearing cup. It would still need a wacky looking spider to attach the inside threaded portion of the freewheel to the cranks somehow.
no bearing small.png
bearing small.png
all small.png
 
ScooterMan101 said:
The two people here in the U.S. who are doing the custom larger mid-drives do not know at this time how to design one, and the other person who is making a mid-drive here has said months ago he is looking into using Direct Mount Cranksets on his mid-drive , SamD ... but he has gone silent for a few months now, so I don't know, I question if he will ever get a Mid-drive available .
GXP FW SECTION.jpg
I've spent some time looking into a SRAM direct mount compatible torque sensing freewheel. The idea was to use a GXP crank since it is wider for a given BB than shimano or raceface. This allows me to use shimano or RF bb cups to sandwich motor mounting plates against the BB, and arrive at the proper bearing width for GXP with a 22-24mm spacer on the non-drive side. GXP fatbike cranks are available too, so that opens the door to a 100mm bb bike with lightweight freewheeling cranks and torque sensor.
Since the direct mount only allows about 4mm of space, the freewheel mechanism needs to be larger diameter to use the wider space claim available as the crank extends outboard.
Unfortunately, today SRAM announced a new crank axle and BB "standard" that makes GXP obsolete. So, there is no point designing a system around cranks that will be hard to get in a year or so. It's tough to keep up with the ever changing bike industry standards. Probably the reason many ebikes use ISIS. That might still be the best solution, if we can accept an extra 1/2 lb of crank weight. Maybe not a big deal. Thoughts?
 
But is the I-S-I-S bottom bracket system going to be available in the Future ? I thought is was or is being phased out .

That was part of the reason for getting a system designed for the Shimano Hollowtec II , and / or the Race Face Direct Mount cranksets.

Since Direct Mount is what I see the future using ( it is really just a 3 piece design )
and
I do not see Shimano changing , except for perhaps keeping the 24mm ID , Outer Bearing and just making a switch to a 3 piece design using direct mount chainrings , but Keeping a 24 mm OD spindle size so as to keep selling their bearings.


I do like your mid-drive design , it is very clean and one of only about 4 that I would consider worth while buying.

Any news about date of ability ? Price ? weight ?

I will have to use a throttle system because of a knee that does not put not much torque/wattage into the pedals/crank arm.
 
ScooterMan101 said:
I do not see Shimano changing , except for perhaps keeping the 24mm ID , Outer Bearing and just making a switch to a 3 piece design using direct mount chainrings , but Keeping a 24 mm OD spindle size so as to keep selling their bearings.

Any news about date of ability ? Price ? weight ?

The nice thing about ISIS is that it is an open standard that has survived (barely) many years and almost any crank vendor in Taiwan can make them. ISIS trials freewheel cranks are readily available. It seems like the proprietary splines (shimano, SRAM, etc) change every 5 years. I don't know if Shimano will change to "keep up" with SRAM and the other 30mm aluminum spindles. I wouldn't be surprised.

As for availability, I don't want to make any promises, but I am hoping for this summer. I'll post other specs/price in the thread I created for it soon.
 
Have you guys seen this ?


Rocky Mountain made exactly what I am looking for: a freewheel that can be mounted on a RaceFace cinch crankset. It is on their new eBike called Altitude Powerplay.
What I don't know though is if the spindle is custom made and what's its length. I am guessing it is for a 73mm bottom bracket.
I'll try to stop by a Rocky Mountain dealer, see if I can order the freewheel.
 

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Remi812 said:
Have you guys seen this ?

Rocky Mountain made exactly what I am looking for: a freewheel that can be mounted on a RaceFace cinch crankset. It is on their new eBike called Altitude Powerplay.
What I don't know though is if the spindle is custom made and what's its length. I am guessing it is for a 73mm bottom bracket.
I'll try to stop by a Rocky Mountain dealer, see if I can order the freewheel.

Cool, let me know if you can get one. I assume they use the DH 83mm spindle which provides another 10mm of space in addition to the thickness of the spider/chainring that is removed...this would give ~14mm for a freewheel. I've been avoiding that solution to keep q-factors close to a 73mm bb width bike. But, I might cave and go that direction since the Cinch cranks are so light... and not many e-bikers are picky about pedaling ergonomics.
I think a simple adapter from Cinch spline to freewheel threads should do the trick with the extra long spindle. We just need to make sure the long spindle has a wide bearing surface so that the bearings can ride further inboard than intended.
 
rocky3.jpg


I found Rocky Mountain's crankset picture at this site
http://velomotion.de/2017/05/rocky-mountain-altitude-powerplay-emtb-ebike/
 
So funny just after reading this, I saw this:

https://www.bikemag.com/gear/components/drivetrain/sram-introduces-dub-crank-bottom-bracket-technology/

Going to 28.99mm from 30mm, because you know... lol

PaulD said:
ScooterMan101 said:
I do not see Shimano changing , except for perhaps keeping the 24mm ID , Outer Bearing and just making a switch to a 3 piece design using direct mount chainrings , but Keeping a 24 mm OD spindle size so as to keep selling their bearings.

Any news about date of ability ? Price ? weight ?

The nice thing about ISIS is that it is an open standard that has survived (barely) many years and almost any crank vendor in Taiwan can make them. ISIS trials freewheel cranks are readily available. It seems like the proprietary splines (shimano, SRAM, etc) change every 5 years. I don't know if Shimano will change to "keep up" with SRAM and the other 30mm aluminum spindles. I wouldn't be surprised.

As for availability, I don't want to make any promises, but I am hoping for this summer. I'll post other specs/price in the thread I created for it soon.
 
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