Extreme Hill Climber Fat Tire MTB Project.

[commuter ebikes]

Forum member Gr8 and I made an HD video comparing his mid drive and my hub drive on a very steep grades: https://www.youtube.com/watch?v=qQqe...ature=youtu.be

The end result is that the mid drive beat the hub motor in the comparison. I am now convinced that mid drives are unequivocally superior to hub motors for steep climbs. My Cromotor has a standard winding and I weigh 100 pounds more than Dan, but I would still choose a mid drive over a hub motor for steep climbs. I built this bike specifically for steep climbs and Dan's mid drive was clearly superior my bike in the comparison.

[Gr8fun]

The 750 mid drive really showed its hill climbing ability when i switched to a 38 tooth. Ring to the 34 cog with the sa igh in low. A cadence of 120 gave maximum speed of 6.5 to7 mph. Worthless for me to pedal above 4 mph. Using only 550 watts. Motor was not hot. Could not have done it with 50 tooth to 34 in low. Power to spare.
Not even remotely possible to catch his machine on flatland. The fat tires do grip the road better. I felt slippage in the corners while commuters bike looked fully in control.

[commuter ebikes]

On both of my bikes, the White Industries freewheel is slipping. I live near White Industries in Petaluma, CA and they want me to bring in my bike and show them the slippage. It really got their attention when I told them that I just finished two identical bikes with their freewheels and both bikes exhibited the same problem. I was hoping for tight, positive engagement while pedaling, not slippage. And the slippage is getting worse every day. The freewheel only lasted three days on one bike and one day on the other.

It will be cool to see their factory and I will be very curious to see why the freewheel is not engaging positively while trying to pedal forward. They are going to look at the spring, pawls and grease in the freewheel.

[commuter ebikes]

I have run into a huge problem with this project. I finished both bikes and on both bikes the mechanical gearing is so low that it had enough torque to cause the White Industries freewheel to strip the threads on the freewheel mounting flange (see photos of this part (the photos are not of the stripped parts)).

I only rode the bikes a few miles before this happened. Apparently the extremely short gearing of the 20T chainring and 23T freewheel multiplied my 150W or so of human power and stripped the Heck out of the threads.

Allow me to illuminate what a huge problem this is:
(1) I need to source two more of these flanges (not a commonly available part!).
(2) I don't imagine that I will be able to remove the freewheel from the flange, which means I cannot free my motor side cover. Hence, I need to find two drive side motor covers (also not a commonly available part).
(3) The freewheels, which cost me $80 each, are almost certainly ruined. I bought a spare one of these White Industries freewheels (another $80) that I cannot use because I obviously cannot run such short gears on this bike.
(4) The three 20T chainrings are now useless to me (yes, I bought a spare). There goes another $75.
(5) When you pull off the drive side cover, you need to reseat the bearing, which would not be a problem if I hadn't laced and trued three of these motors into rims.
(6) I don't reuse spokes and nipples, so I need to buy 3 X 36 custom length spokes and nipples. That is about $140 for new spokes and nipples.
(7) I don't mind building wheels, but I will have to take apart and rebuild three wheels which I never even got to use.
(8) I need to remove and replace the two rear wheels which are on the bike which takes two hours each.
(9) I will need to wait for the parts to come from overseas.
(10) I will need to choose taller gears for the new drivetrain which means buying new freewheels and chainrings.
(11) This frame only allows up to a 46T chainring, so the new gearing (if I go tall) will not be of use to me because I travel at about 35mph.

I am very frustrated. I would never have imagined that human power could strip these steel threads.

[commuter ebikes]

I definitely like a challenge, but this is very disappointing to me. Should I have anticipated that the freewheel would strip the threads on the freewheel mounting flange? I did not see that coming. I built up two bikes like this when I could have just made one and tested it before diving in even to the point of buying spare parts and building a spare wheel.

If you're wondering how my spare wheel got caught up in this, I removed the part in the photo in order to put a magnet to it because I thought it might be aluminum. It is steel.

In practice, however, I will ride the two bikes that I built while I am waiting for all the parts to come, even though the pedals just spin without transferring power to the wheel. I always ghost pedal anyway.

I love working on bikes, but I don't work on other people's bikes. I spend a lot of money to go to United Bicycle Institute, and they really emphasize to practice, practice, practice. I have now created a lot of work for myself so I look forward to the practice.

I had high hopes for this hub motor hill climber project, but I am now very hesitant about installing low gearing on this hub motor. Please learn from my costly failed experiments and use mid drives if you will be climbing grades.

I am afraid that I will now shoot for tall gears. I have previously run a 46T chainring and crappy 16-19-22 3-speed freewheel on this rig, and it spun out at about 21 mph. I will probably choose a White Industries 16T freewheel (the tallest gearing available) so I can at least have a quality freewheel.

Hopefully the 1 X 1 setup with a 46T chainring and 16T freewheel will not strip the threads again!

[commuter ebikes]

Things are looking up already. The very busy Vladimir S. at Zelena Vozila has two new Cromotors ready for me with 170mm dropouts, spare axles, freewheel mounting flanges to replace my stripped units, drive side motor covers and extra snap rings.

I ordered these 170mm dropout motors and spare axles with a very long total axle length (260mm!). I will be hopefully be able to jam in enough axle spacers to spread my steel frame and cram a 5-speed freewheel in there and still have enough axle length to fit my torque plates as well as engage all of the threads on my axle nuts.

The 5-speed freewheel has a 13T small cog so that will raise my spinout speed by about 19% (to 25mph). So I am back to tall gearing for commuting in my flat city.

My last hope of obtaining short gearing would be to weld in the threaded shaft of the freewheel and assemble the rest of the freewheel parts while it is on the side cover. Unfortunately, there is a flange in the way. This, together with the lack of access on the underside of the freewheel, will almost certainly make it impossible to weld the freewheel body onto the side cover. Plus who wants to have to lace and true the wheel, buy new spokes, nipples, freewheel mounting flange and side cover, and reseat an axle bearing every time you replace the freewheel? You have to think that welding a freewheel onto a hub motor side cover is a terrible idea.

The flange that would get in the way of welding at the threads is pictured here. It has four notches in it.

[Alan B]

Sorry to hear of your problems. I don't understand what is happening here.

Did you visit White Industries already?

Before going forward I would suggest conducting a thorough failure and root cause analysis to understand what actually is happening, and where the torque transmission occurring. How many threads are engaged and what is resting on what when the freewheel is fully seated? Is there a spacer between the freewheel and the hubmotor? White Industries may be a huge help in all this.

White Freewheels are often used to transmit MOTOR torque from mid drives to the rear wheel, You are only asking for it to transfer pedal power. This failure seems surprising.

Note that a mid drive will put considerably more torque on the freewheel threads than this hubmotor setup.

If the freewheel is slipping on the threads it would seem possible to remove it. Do you have a removal tool that will fit the slots over the large axle?

[calfee20]

I would take my wheels to a shop that has a wide enough press to seat the bearings. Then you wouldn't have to remake the wheels. Why has this not been a point of failure for every BBSHD driving a freewheel which is quite common.

I know you won't want to hear this but I think I could assemble that without a press.

[commuter ebikes]

I tried pressing the bearing into the freewheel mounting flange (easy) and then trying to press the side cover onto the axle (nope!) here, at 20:53 in this video https://www.youtube.com/watch?v=QA2qQkexj2g.

I have tried pressing the drive side cover onto the axle using the clamping pressure of the eight side cover bolts, but the bearing did not seat completely. One could try to use a socket to seat a bearing as seen at 2:39 in this video https://www.youtube.com/watch?v=QETuIW0_0wo

[Gr8fun]

I have put one part in freezer the other in oven. Just drop in place. No press needed. No real high heat either.

[commuter ebikes]

I had not thought of the freezer and oven. Thanks, Dan. I would choose "motor in the oven, hub flange and bearing assembly in the oven". I wonder what the maximum safe heat would be for a sealed cartridge bearing.

[Gr8fun]

Something is very wrong with this picture. Those freewheels should not have stripped out. Ask white. This is not looking good.

[Gr8fun]

If anything should have failed climbing those hills it should have been my sturmey 3 speed hub. But then again they have been breaking for over a hundred years to learn how to make them as durable as they are today. It is up to me to find the breaking point.

[MoneyPit]

Has anyone tried this experiment with an AWD hub motor bike? Mine is amazing in hills although its not at the power levels yours are and I have only informally tested it in hills at home (Monterey CA area). I originally built it up to run as a commuter on flat ground - my business is in Fresno CA where its table-flat.

I'm running two Bafang 750w motors with a 52v Luna Storm battery for rear (25R cells) and two parallel'd Luna 30Q mini cubes for the front. 35a controllers on each motor. Managing traction on the front motor is surprisingly straightforward but then again its a great big fat bike. I originally hung the battery and controller for the front in a bag under the bars so the weight would aid in traction, but found it unnecessary and now the battery is in a rear rack trunk while the controller is in a (much smaller) handlebar bag up front to minimize exposed wiring.

I'm not expecting such a setup to beat a mid-drive, but I'm pretty sure it would beat up on a rear-drive-only hub motor even running 72v. AWD has been extraordinary on a bike, at least to me.

[Gr8fun]

Geared hub front and rear. drive will not match a mid drive. Did see there was a hub motor with a sturmey 5 speed built in. That would do it..... Maybe. A bit spendy.

[commuter ebikes]

I spent a long time at White Industries this morning talking with Alec, mostly about how the freewheel driver (I was calling it a freewheel body) engages the freewheel mounting flange and thus driving the wheel forward. White Industries is a huge, high tech outfit; anybody would have been impressed. Alec was generous with his time, and he was so knowledgeable about the matter being discussed that the conversation with him made my suffering over my twin catastrophic mechanical failures worth it!

The end result is that White Industries is going to manufacture ten freewheel mounting flanges (pictured in post #123 above) made of 8620 steel, case hardened and then electroless nickel plated. This order will set me back about $2,000.

The problem was twofold. One problem was that the major diameter of the 1.370 inch (or 1.375 inch, depending on who you ask) X 24 tpi male threads on my existing freewheel mounting flanges was a bit too small. This resulted in threads that were too shallow. I had this same problem when I tried to roll spoke threads at home on a Cyclo spoke threading tool. The steel spoke threads were too shallow and the brass nipple stripped the spoke threads (I solved this problem by buying spokes threaded on a Phil Wood machine).

When my freewheel mounting threads stripped, the nearly indestructable threads on the inside of the White Industries freewheel driver just tore through the shallow threads on my freewheel mounting flange, which I believe is made of "automotive steel" which may be 1018 steel.

The other contributing factor was how I had installed the freewheel on my flange. I used no freewheel spacers, so the underside on the freewheel driver had nothing to clamp on to, except a small surface at the top of the threads (I will post photos of these clamping surfaces). The freewheel will be less likely to strip the male threads (on the freewheel mounting flange) if I maximize the clamping surface area. This will be accomplished by tightening the freewheel against an aluminum freewheel spacer.

Another important point is that some freewheels have an open end (pictured below). This functions well because the freewheel gets tightened all the way into the freewheel spacer which gives you all of the clamping surface area that a freewheel spacer can provide.

All of the White Industries freewheels have the locking flange at the top of the threads; if you don't use freewheel spacers, you only get the small surface area at the inner top of the locking flange which, in my case, allowed the freewheel to lose contact with this reduced clamping surface area and proceed to strip the threads.

[commuter ebikes]

This is a freewheel which has no material to interfere with tightening it all of the way down against a freewheel spacer:



This is a good thing because when you tighten it down, the bottom of the freewheel driver gets maximum contact with the freewheel spacer for maximum clamping and thus resistance to losing contact and getting a chance to spin forward and strip the threads.

[Alan B]

That's what I was concerned about. I didn't use my White freewheel exactly because of that reason, and I used the Dicta brand instead, because they sit all the way down on the Cromotor. I was planning to turn off the extra threads so the White could sit fully against the flange, but never got around to it. The Dicta works fine, but it does wear out about as often as my Moped tires do, so I just replace them at the same time. Lubricating the Dicta does extend its life as well. Additionally the White is wider and I'm not sure there is enough space on my 135mm setup.

[commuter ebikes]

If you have the room (135mm would be really tight!), you would use enough freewheel spacers to allow a little empty space between the top of the freewheel mounting threads and the inside of the bottom of the locking flange (if you are using, for example, a White Industries freewheel). This gets you maximum clamping surface area between the freewheel and flange, at the freewheel spacer and bottom of the freewheel driver.

Alan, you totally nailed it when you wondered where the freewheel lay against the motor, asking if I had used freewheel spacers. By not using freewheel spacers, I failed to take advantage of the flat circular area (pictured below) at the base of the freewheel driver.

[commuter ebikes]

Hopefully, these two pictures will help show how to maximize the clamping surface area. Maximizing the surface area between freewheel and the flange helps prevent the freewheel from losing contact with this clamping surface area and being able to strip the threads.