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Extreme Hill Climber Fat Tire MTB Project.

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  • commuter ebikes
    replied
    The powder coater says that they are swamped. They have had my two frames and small parts for two months, and they said that it might take another three months. I was trying to finish all of my tasks before the powder coating was done, but all I have left is redoing the harnesses so I will probably end up waiting on the powder coater with nothing else to do.

    For my wiring harnesses, I had to buy 30 more of these connectors: http://www.allelectronics.com/item/c...%3A1%3BN%3B%7D.

    I bought https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 and https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1.

    I modified another one of these tools http://www.bikeman.com/WIND-FWTOOL.html. The cobalt steel bit would not cut the tool steel, but I used a stone on a large die grinder which worked very well.

    This won't be the first project which is delayed and waiting on the powder coater. I am very glad that I have two other bikes to ride while I wait...and wait.
    Last edited by commuter ebikes; 07-09-2017, 03:26 PM.

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  • commuter ebikes
    replied
    Here are the goods:

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    Last edited by commuter ebikes; 06-27-2017, 11:41 AM.

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  • commuter ebikes
    replied
    I have had my nose to the grindstone for the last few weeks, and I have made enough progress to post an update:

    (1) All of the wheels are laced and trued. The last wheel had a rim bent in three different places (because I was jumping like a moron), so it was almost impossible to true. The best that I could get the dish is 6.5mm (biasing the tire toward the drive side). If I ever want to do more jumping, I will use that wheel. If I can commit to staying on the ground, I will replace the rim which is a project in itself because the Rolling Darryl rims are only seasonally available, and I would have to drill my own cutout holes and then refinish the rim (I powder coat it).

    (2) The controller heat sinks are built. I had to buy a 1-7/8" hole saw. I took them to the powder coater.

    (3) I built the battery boxes. My friend who was doing it for me got a girlfriend, so he became too busy to do it.

    (4) My electronics tech converted my two CAs from DP-S to DP.

    (5) The same electronics tech fixed a 36V battery that suffered physical damage causing many spot welds to become separated.

    (6) I amassed a large stockpile of 6 conductor stranded cable for my harnesses.

    (7) I got a spare White Industries 23t freewheel and another freewheel removal tool which I will modify differently than my previous tool modification. That freewheel removal tool, as it comes from the factory, will not fit over the fat Cromotor axle. This time I am going to drill the hole larger (last time I shortened the tool). We'll see how this bit https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 drills through the case hardened chromoly tool steel.

    The powder coater is taking a LONG time to powder coat the two frames and small parts. It has already been about 6 weeks. One time they took 10 weeks.

    I am currently making five master harnesses, any one of which can be used on any of my four bikes.

    Once I get the harnesses built and the frames back from the powder coater, I have all of the other parts needed for assembly. We'll see what new problems arise upon assembly.
    Last edited by commuter ebikes; 06-25-2017, 04:54 PM.

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  • commuter ebikes
    replied
    So helpful!

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  • Alan B
    replied
    For continuous operating at near zero speeds the power limit is probably in the 500-700W range. Battery current will need to be limited to about 10 amps max, perhaps less. Experimentation will be required to find out.

    Here's some comparison data for some of my ebikes awhile back: Click image for larger version  Name:	ebike thrust chart.PNG Views:	1 Size:	79.3 KB ID:	37256



    Here are some very rough approximate numbers for near-stall uphill trail speeds:

    Assuming bike and rider and gear weighs 330 lbs,
    A gradient of 20% makes the load about 700W at 5 mph,
    The thrust required just for the gradient is about 55 pounds

    The CroMotor above has 23.5 inch tires and a 120 motor amp controller and produces about 90 pounds of thrust max at near zero speed. If we convert this to 29" tires the thrust drops to 75 pounds due to the large tire penalty. Limiting the heat to about 700W for continuous operation in this mode is about half as much as the max shown above, so about 0.707 times the current and thrust, or 85A and 50 pounds of thrust.

    With the Cromotor at 5 MPH fed with 700W all of the power will go to heat because 50 pounds of thrust will not move the bike against 55 pounds of gradient load. With the Cyclone operating at decent RPM through the gears, perhaps 20% of the power will go to heat. The power dissipation is primarily related to the surface area of the motor, so the Cyclone can dissipate about half the Cromotor. So if the Cromotor can dissipate 700W and just sit there stalled whereas you can feed the Cyclone 1500W and it could dissipate 300W while it is doing 1200W of work which is enough power to climb the grade at something like 9 mph. With the Cromotor you will only need about 5 pounds of thrust from the pedals to get moving at low speeds since the Cromotor is putting out 50 pounds (and getting very hot). So you won't need the low gears with the Cromotor on, it will be about like pedaling on almost level ground. With the Cromotor off your pedaling effort will increase by a factor of 11.

    This is about the same as the Bonanza was with only rear wheel drive. Going to 2 wheel drive totally changed that. Since one motor pretty much cancels the gradient, the second motor is operating like it would on a level surface, and the total of the two are capable of more speed than most trail conditions allow. Also both motors run cool since they are not stalled anymore and have better airflow and the heat dissipation has doubled while each carries half the load.

    Estimates and Calculations subject to errors and approximations. :)
    Last edited by Alan B; 06-07-2017, 03:51 PM. Reason: fixing a few words

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  • commuter ebikes
    replied
    Originally posted by Alan B View Post
    A Cromotor is a wonderful thing, but very heavy, and mounted in those huge wheels it is really not a good fit for dirt trails. The current required to spin those big tires on steep hills with lots of weight to carry is going to make it very hot. It is just the wrong choice. We actually already proved that there in Marin on that day, the BBSHD made it up the hill and didn't get warm and the Cromotor was getting too hot and didn't really have adequate torque, and that wasn't as steep as those roads get.

    I would abandon that plan, it is just going to soak up a lot of effort and funds and deliver a poor result with insufficient torque and excess axle weight.

    A BBSHD or Cyclone would be more fun and give you lots of pedaling gears, and make a lighter bike. I would think you could easily trade a Cromotor for a Cyclone so not have to spend cash.
    I'm afraid I have a bit of a mania about needing to hide my motor, controller and battery. I fully recognize that this mania is a weakness on my part. So within the confines of a rear hub motor, one wonders if I could depend on the extremely low gearing of the drivetrain and a reduced power setting in low and medium settings of the 3-speed switch. I just lost 55 pounds and I hope to lose 55 more, so that will help with the weight penalty of the Cromotor. A Cromotor weighs about 13.4 pounds more than a Cyclone, which I imagine gives the Cromotor a better ability to produce power and, more importantly, manage heat.

    I also have a stipulation that all of my ebikes have the same motor and controller with interchangeable batteries, harnesses, and as many other bike parts as possible. These Hillclimbers that I am building differ only in the frame, chainring, freewheel, headset, axle width and lack of derailleur and trigger shifter. I need to minimize the amount of spare parts because I stock spare parts and there is only so much room in my garage.

    I wonder what power settings will be low enough to keep the motor under 100 degrees C while climbing steep hills. On the street, I can run a continuous 2.5kW without overheating. Going up a steep hill and pedaling with the single extreme granny gear (1-7 mph pedaling range) , I will be curious to see how much continuous power I can run and still keep the motor temps in the double digits. If it does get over 100 degrees, I could turn off the motor and just pedal while the motor cools. I think I will designate both the low and medium settings in the 3-speed switch the task of climbing steep hills.
    Last edited by commuter ebikes; 06-07-2017, 10:09 AM.

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  • Alan B
    replied
    A Cromotor is a wonderful thing, but very heavy, and mounted in those huge wheels it is really not a good fit for dirt trails. The current required to spin those big tires on steep hills with lots of weight to carry is going to make it very hot. It is just the wrong choice. We actually already proved that there in Marin on that day, the BBSHD made it up the hill and didn't get warm and the Cromotor was getting too hot and didn't really have adequate torque, and that wasn't as steep as those roads get.

    I would abandon that plan, it is just going to soak up a lot of effort and funds and deliver a poor result with insufficient torque and excess axle weight.

    A BBSHD or Cyclone would be more fun and give you lots of pedaling gears, and make a lighter bike. I would think you could easily trade a Cromotor for a Cyclone so not have to spend cash.

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  • commuter ebikes
    replied
    Originally posted by Sneakers915 View Post
    No cop is going to confiscate your bike, at most you'd get a ticket and even that seems very remote. You're in CA, ebikes are legal pretty much anywhere aren't they?
    We have the three levels that are legal, and all of my ebikes are above both power and speed levels. When I built the bikes, I built exactly what I wanted; apparently California thinks that is too much power and speed. As such, it is an illegal homemade motorcycle. It would be at an officer's discretion to warn, ticket or confiscate. So that is why I have always been so careful to hide the motor, battery and controller and always pedal.

    In practice, however, I ride this around everyday and I have never been pulled over. The cops either don't notice the bike, or if they notice I often get a smile.

    I'm sure the key to avoiding legal problems is driving safely. Blowing through a stop sign or driving like a jerk would make a terrible impression.
    Last edited by commuter ebikes; 06-06-2017, 08:57 AM.

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  • Sneakers915
    replied
    No cop is going to confiscate your bike, at most you'd get a ticket and even that seems very remote. You're in CA, ebikes are legal pretty much anywhere aren't they?

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  • commuter ebikes
    replied
    Originally posted by Alan B View Post
    A hill climbing application would be better served with a mid drive. With a BBSHD, for example, a full rear cluster could be installed, and a single front chainring. This could easily cover a 3:1 or more gearing range and get the motor operating at a higher RPM while providing the rider with proper pedaling cadence.
    Yes, gearing is a great thing. I agree with you about the mid drive for a better range of gears, but I had three Cromotors laying around. I will use the motor to travel 7.3 miles at 35mph to the trailhead and maybe not use the motor at all in the park, if I can resist turning on the motor. Hopefully this extremely low gearing can pedal the 350 pound bike + rider + cargo up the steep hills.

    I was able to get five wheels built with the dishing off by 2-4mm with the tire biased toward the drive side; if that tire rubs the frame, I will have to run a slightly more narrow tire in the rear. The spoke tension values (on the Park Tool TM-1) are between 15 and 30 units. Back to Alan's point, a mid drive leaves the front and rear unmolested. On most bikes, the area on the drive side between the hub and axle nut has so many parts competing for space. I envy you mid drive guys, but I am so paranoid about a cop seeing any electronics because I am afraid they will confiscate my rig.

    The electronics tech found physical damage on one of my 36V batteries. Some of the strips to popped off the cells. This may have occurred when the battery fell off a stool while I had it in the garage. The electronics tech will spot weld the strips back on.
    Last edited by commuter ebikes; 06-07-2017, 01:15 PM.

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  • Alan B
    replied
    A hill climbing application would be better served with a mid drive. With a BBSHD, for example, a full rear cluster could be installed, and a single front chainring. This could easily cover a 3:1 or more gearing range and get the motor operating at a higher RPM while providing the rider with proper pedaling cadence.

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  • commuter ebikes
    replied
    Project update:

    (1) The two frames are at the powder coater and will be ready anyday. My wife bought me this for my birthday https://www.amazon.com/Park-Tool-Bot.../dp/B000C12AF0 so I will clean up any powder overspray in the BB threads.

    (2) I delegated the task of building the four battery boxes (two on each bike) to my buddy who comes over every Saturday night and works in the garage with me. I pay him $13/hour. He is doing a great job so far. He is just duplicating a battery box that I have on my other bike.

    (3) I am currently working my way through building 6 wheels with Cromotors and Surly Rolling Darryl (82mm) rims. This job was made tougher by trying to cut and thread the spokes myself with a Cyclo spoke threading machine using 13ga spokes from Taiwan. The spokes were not top quality (softer steel than Sapim spokes) and the Cyclo spoke threading machine produced threads that were not as deep as threads rolled on by a Phil Wood machine. I ended up not even using the Taiwanese spokes and purchasing threaded Sapim spokes that were rolled on a Phil Wood machine. Those spokes had harder steel and deeper threads. At one point, after I had a wheel laced, I had to unlace it, completely rebuild the motor (it was cogging because I had not completely seated one bearing) and relace the wheel. These wheels must be the most difficult to true. The spoke length is correct, but the combination of the Cromotor and wide rim results in about a six hour job to true the wheel. Also, the manufacturer of the custom wide axle has the motor set off to the brake side by 14mm so the dishing is nearly impossible. If I were to set the dishing correctly, the spoke tension on the brake side would be about 5 units (on the Park tensiometer) and about 30 units on the freewheel side. I split the difference and leave the dishing 7mm off center (tire biased toward the drive side) so that the spokes can have more consistent tension.

    (4) As part of this project, I am completely redoing all of the harnesses on all 4 of my bikes (they all use the same harness), as well as making at least one spare harness. I delegated the job of making one prototype master harness to a professional electronics technician, and I am also making a separate prototype master wiring harness myself. I scored some 22ga 6 conductor cable for this job. It was fun deconstructing the wiring from an existing bike; I got to figure out every little wiring detail. The 5V harness that I deconstructed had some shoddy work on it; the technician had used a lot of 28-30ga wire on it, all 6 wires (ignition, e-brake (regen) and temp sensor) being white. I need my wires a little thicker and color coded. The bikes have a multifunction switch which handles power, regen and 3-speeds. It is not easy to set the 3 speeds so that it goes Low, Medium and High as you toggle from left, center to right respectively.

    (5) I am converting my CA V3 DP-S to DP because I hate the spoke magnet, sensor and wire. That is all unnecessary clutter because a DP senses the rotations of the motor. I delegated one conversion to the electronics tech and I will do one conversion myself (it is only one solder joint, see diagram below).

    (6) The electronics tech is fixing one 36V battery which has some bad cells. I damaged those cells by drawing too much current while I was testing an experimental Kevlar tire liner at 0psi (riding to work) with no limit on the current. The Kevlar tire liner didn't work out because it had no acrylic; Kevlar needs acrylic in order to function properly, and the acrylic makes it rigid.

    (7) Everything else is ready, and I will assemble these bikes in August. I have two paid helpers coming: my regular helper/buddy Lloyd and a guy at work who is always telling me what a great bike mechanic he is, so I thought I would illuminate his claims. All three of us work at UPS together, so that should be a fun group activity. Click image for larger version  Name:	unnamed.png Views:	1 Size:	167.5 KB ID:	36969

    Last edited by commuter ebikes; 06-04-2017, 09:10 AM.

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  • commuter ebikes
    replied
    Originally posted by ri9rashed View Post
    Fat Tire Hill Climber looks very nice but how it works?
    The project in this thread is this prototype bike getting a frame off rebuild: https://www.youtube.com/watch?v=dENXWp-qqSo. With the 46 X 16 gearing, I found the gears way too short for use as a commuter bike. Also, it had this freewheel http://www.ebay.com/itm/Bicycle-Scoo...38.m2548.l4275 which can be almost impossible to remove, usually requiring a destructive freewheel removal. Gosh, I hated that freewheel. I always build bikes in pairs and I stock spare parts; when I saw the spare 3-speed freewheels hanging on the pegboard, I always felt disdain.

    One time I was mountain biking using the bike in the video, going up steep single track on a hot day. I had it in the lowest gear and I was pedaling as much as I could. It was going uphill fine, but the temp sensor said 105.6 degrees Celsius. I stopped, said goodbye to the group, and headed down the hill. The high motor temperature reading on that climb was the impetus for this project. That was a mid drive riding group, by the way, and they had no problems climbing steep hills without overheating.

    The catalyst for this project is when I was unable to sell the bare frame when I had the idea to switch to a 190mm dropout frame. Not that I tried very hard to sell the bare 170mm dropout frame--I only made a post on this forum and left it up for a week. I had filed out the dropouts for a larger 16mm axle, so the frame would only be of use to someone using a 16mm axle or willing to weld in new dropouts. I do love these frames so I didn't mind keeping them, but there was definitely a moment when I was "stuck with the frames" that only allowed up to a 46T chainring.

    This bike ought to be able to pedal up anything. I will use the motor for everything else, which I realize is most of the time. I wonder if the fake pedaling will be convincing. Riding around town at 35 mph and fake pedaling with a 20T chainring is going to look hilarious to somebody who understands chainrings; maybe they will think I have some extreme IGH.

    Honestly, I hate getting my bikes dirty so I much prefer riding on the street. There are countless very steep roads in my area. In practice, I will usually use these hillclimbers on those steep paved roads. I like to go riding with friends so we will take out the identical short geared bikes on a route with very steep hills.

    I haven't even sent the frames to the powder coater yet, and they take 4-10 weeks to powder coat frames. While the frames are at the powder coater, I am going to redo the wiring harnesses, modify the CA from this http://www.ebikes.ca/shop/electric-b...s/ca3-dps.html to this http://www.ebikes.ca/shop/electric-b...ts/ca3-dp.html (this modification is just a single solder joint) and build bomb proof aluminum battery boxes. When I redo the wiring harnesses, they will be able to be used on any of my four bikes, and I will have a few spare wiring harnesses at the ready.

    I also used the rebuild as an opportunity to upgrade the headset from Cane Creek to Chris King, upgrade the derailleur hanger from aluminum to steel, and switch in black nipples and new spokes. Some of my wheels had silver nipples and for some reason shiny parts bother me.

    I like to completely rebuild a bike every two years. Upon taking these two bikes apart, I found a lot of grime, three worn out BB bearings, rust in the bottom of one BB, overly thin wires in the ignition wiring in one harness and red paint from a previous build showing through my matte black powder coating on one frame. I also had an issue with a rear tire rubbing on the frame which I will rectify by filing on the frame a little, dishing the wheel as much as I can, and running a slightly more narrow rear tire if needed. Currently, the rear tires are 4.80" wide. I see that there are many choices for 4.70" and 4.60" wide tires.
    Last edited by commuter ebikes; 05-06-2017, 11:19 AM.

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  • ri9rashed
    replied
    Fat Tire Hill Climber looks very nice but how it works?

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  • commuter ebikes
    replied
    These pictures show what a tight fit the White Industries freewheel is. The bolts for my torque plate require some space. 170mm dropouts and I can only fit a single speed!

    Actually, there is no extra room anywhere because the axle nuts come up flush against the ends of the axle. Crowded house.

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