DiamondBack, Cyclone 650watts and Dewalt A123 packs

[amberwolf]

It's hard to tell without a high-res closeup of the break, but it looks like the bolt is pressing it around the curve and bending it there. That pre-stresses the whole thing, and the shear line is right across the weakest part, with the bolt holes.

It almost looks like it *tore*, rather than sheared, which suggests it is being wiggled back and forth, which will fatigue the metal and cause this, too. Is that attach point tab on the rack steel or aluminum? Look like steel, but hard to tell for sure.

One reason wiggle happens is because the rack is bolted to it's side supports, AFAICS, rather than welded to them, so it can move back and forth a bit more easily (even if only a teensy bit each time). Another reason is that the rack has nothing to keep it from swaying and twisting side to side at the rear end, which causes the front attach point to be twisted a teensy bit each time that happens. This will fatigue the front rack attach point.

To fix that, put an X brace across the vertical supports to the rear end of whatever rack you use, and it will stiffen it up at least a little. A second X across the vertical supports under the rack up to the front attach point might help too. Just make sure the X is fixed in it's center, so the whole thing can't pivot

It'd be interesting to see video from a camera securely mounted beside the seatpost so it can record along the rack's side as you ride. I bet it will show significant sway on the rear end.

[kfong]

Amberwolf, I had it bolted on rather tight, so I don’t think it had any movement. I also used a fiber lock nut to secure it. The plate is steel; the whole rear rack is steel. The fall that I had could have done most of the damage. In reality, most of my breakdowns have come about due to me jumping. I started to do this last year in the fall and the breakdowns have been coming on very frequently since. With all that dead battery weight coming down on the rack, it’s taking a lot of abuse. I should be able to come up with a more solid repair. I’ll try to see if I can beef up the rack even more. Since I don’t do any welding there might not be much that I can do for bracing. Once I get the rear rack issue solved, then I’m pretty sure this bike will once again be very reliable out in the trails. The new motor mounts have been holding up quite well, even going over log piles. Something I would not have done with the old motor mount setup.

[amberwolf]

Amberwolf, I had it bolted on rather tight, so I don’t think it had any movement.

I bet there is more movement than you think, although you might not notice it. Can you physically grab the rear end of the rack and make it sway even a tiny little bit side to side (vs the bike frame position)? I'd bet this is possible with almost any rack out there, even of welded construction.

In many cases I don't think it makes a great deal of difference, but in extreme-use cases like yours, it can't be helping any.

I'd love to see someone do that camera test with racks like this. I have two bolt-together premade racks I'll see if I can test, plus one crappy welded rack I made. I have to build a camera mount first, and see if I can borrow a camera that does not have any extendable mechanical-focus mechanism for the lens like mine does (otherwise the vibration I intend to force during the pothole tests might damage the camera).

Steel flexes; it's one reason why it doesn't just break like aluminum does, which tends not to flex as much. But repeated tiny flexings still induce fatigue and eventually cracking. Depending on the metal type and structure it can happen quickly, too.

I also used a fiber lock nut to secure it. The plate is steel; the whole rear rack is steel. The fall that I had could have done most of the damage. In reality, most of my breakdowns have come about due to me jumping.

I don't doubt that major failures can be caused by that kind of stress, but I do think that other stresses are contributing. I just see too many rack failures posted up on the web that don't look like they should be happening based on the rack design, unless there is some sort of sidesway that is causing fatigue--the rack should not move in order to break otherwise, based on the way they are made. I'm no materials guy or mechanical engineer, so I don't know any of this for sure--it's just an intuition thing, which is often wrong.

I’ll try to see if I can beef up the rack even more. Since I don’t do any welding there might not be much that I can do for bracing.

You can make a reasonably stiff bolt-on X-member, if you can take steel tubing and hammer down the ends flat, then bend them to conform to the shape of the tubes you're connecting to at the angle they'll be connected at. Then make a matching piece for the other side to clamp it with, or even a flat plate.

To connect them at the middle of the X, dent the tubing in where they meet so they'll be inset against each other and can't easily rotate when bolted together, then drill a hole thru both at that point and bolt them tightly.

You could also machine something out of a solid bar to do this, too.

Neither of those is as sturdy as welding, but it might help if the X goes far enough down the rear brace to the dropout mounting point. That would mean an X that has short top arms and very long bottom arms, a little like a chromosome (but in a pure X shape rather than with any bends in the arms). The idea is to make as long a base for a triangle as possible, to give the stiffest shape over the longest possible portion of the frame.

[kfong]

The rear rack is now repaired; the metal on the original rack was actually softer than I had thought. I was able the tear off the rest of the broken plate with a pair of pliers. I road the bike yesterday with several jumps and did not see any problems, I think this setup should hold. I don’t expect any problems with the repair. Hopefully the rest of the rack holds up as well. I did have to tighten up the rear wheel spokes; they are taking a beating from the jumps and torque. I was planning to add more packs in the triangle and actually had the parts made, but in the end I didn’t want to give up the water bottle after riding one time with out it. I also didn’t want any more weight as well. The bike looks like it’s pretty much finalized for now until things break again. I would like to put back a mirror for riding the streets, but I have not found one that can outlast the trails.

[kfong]

I finally had to replace the freewheel a few days ago after a ride. The pawls on it finally gave out and only one was working making it difficult to pedal. Luckily I was able to get spare parts from an ES member. I was not able to get the freewheel off the crank. It was solidly fused to it. I ended up using the crank from the spares. I put anti-seize compound this time around.

All this recent effort was wasted. I finally thought I had all the bugs worked out on the bike and have broken everything that could break on it. Well I was wrong. Took the bike out to the trails today and rode it hard like I usually do. Did a jump off a tree root, landed and immediately thought my handle bars had dropped. I’m thinking no-way, since I knew it was tighten and had not given me problems. I look down and find the frame had broken. I was lucky that it didn’t snap in two. It wasn’t much longer that it broke off completely trying to walk it out of the woods. This is where the fun begins; try hauling a 62 lb. bike with no support out of the woods. I ended up sticking a wood branch into the top tube and hanging the front tire off it. Holding the branch while rolling the back tire all the way back to the car. The cables kept me from being able to separate the two. I’m glad I didn’t get hurt, but bummed that the bike is now trashed. It’s going to be hard to be without a good utility bike for errands. Time to build another.

You would think I would have stopped jumping. Oh well, next bike will just have to be tougher.

[jateureka]

Wow, I've seen the forks crack near the crown but nothing like that. You're very lucky you didn't get hurt.
Now you have an excuse to get that full suspension set up you obviously need to satisfy your desire to do jumps!

[kfong]

Yeah it could have been a lot worse. I was just lucky. I would have never expected it to break like that as well. I also discovered the bike is steel framed and not chrom-moly. I did find another donor bike locally that is out of chrom-moly, but has a cheap front suspension, hopefully it will hold up to my abuse. I really need to finish my full suspension BMC build, but I still have to have a utility bike for errands. So getting this bike repaired has priority.

[amberwolf]

WOW. I somehow missed the update to this thread on the 6th. I've never seen the whole headstock just snap off like that! That could have really sucked if it'd snapped all the way thru as you were landing.

Can you use the fork from this one on the other bike, instead of it's suspension fork? Assuming you think this fork is better than the cheap suspension one.

[kfong]

Amberwolf, unfortunately the new frame has a 1.25” head tube. The broken Diamondback is a 1”. Just as well since, I was never able to upgrade it due to the old style headset. I’m going to pick up the replacement bike later today. I’ll know more about the front shock once I have the bike. I don’t plan to put much into this, since it’s suppose to be just a utility bike for errands and shopping. The only reason I’ve been riding it so hard is because it’s my only ebike at this time. Once the other bikes get running. It will see a much easier life. The full suspension BMC build is coming along, but this weekend, my CNC computer crapped out. I need to fix it before I can move on. In the mean time I’m really missing my ride and the trails. I’m hoping I can just bolt on my cyclone tonight and be riding tomorrow.

WOW. I somehow missed the update to this thread on the 6th. I've never seen the whole headstock just snap off like that! That could have really sucked if it'd snapped all the way thru as you were landing.

Can you use the fork from this one on the other bike, instead of it's suspension fork? Assuming you think this fork is better than the cheap suspension one.

[kfong]

Well, when life gives you lemons. Here is my Diamondback with a new purpose in life. I needed a way to true my rims and it occurred to me that the old frame could still serve a purpose. I ended up cutting off the broken ends with a hacksaw.

[amberwolf]

That's a nifty idea. And now you also have spare tubing, headset, etc for other projects.

Amberwolf, unfortunately the new frame has a 1.25” head tube. The broken Diamondback is a 1”.

I have seen somewhere an interesting in-headtube-shock that uses such a configuration. Not a lot of travel possible, depending on the length of the old fork stem vs the new headtube, but it might be better if the old fork is a better made one than the new one.

[kfong]

Here is the replacement bike I picked up for $95. It’s a GT Palomar in great condition. I’m really happy with the purchase. The bike frame is chrom-moly. From what I have read on the frame, it’s able to take all the abuse I can give it. The rest of the components are ok, a little better than dept. store stuff. The front shock is a low end RST 191 Omni CL. It looks like it should hold up. It’s an elastomer shock with 63mm of travel, requiring little maintenance. For now I’m content with leaving the bike as is. Here are pics, ready for Ebike surgery.

[kfong]

The operation was a success, the donor bike lives. Here are pics of the converted GT. I now plan to get a Cycle Analyst so I can get rid of the wattmeter and long wires. I rode it today and I’m really happy with the results. The right shifter has been moved to the left side. The left shifter has been removed. Shifting is smoother than my old bike. The cheap front shock works fine for street use. The braking is better as well on this bike. The geometry feels better. I can’t wait to take it out on the trails and bash on it. I did have to cut part of the rear fender to get the controller to fit. I also had to redo the controller mounts so it’s lower in profile. There is less space in the back with this bike and I wanted the controller like it was with the old setup.

[kfong]

I just put back all the pics from this thread from my archives. Hopefully the server won't loose them again. Looks like I will be prepping this bike for more serious trail riding now, since my BMC build has just broken. I seem to be really hard on equipment since I keep getting break downs.

[kfong]

It's been a while since I had to do post anything on this bike. The Cyclone setup has been ultra reliable until today. I've been taking it out on the trails recently with a new front 100mm RST Omega fork, it's been quite rideable. It's still a low end suspension fork, but way better than the previous elastomer fork. The geometry on the GT works good in the trails. I probably should of picked up a better fork, but still want to keep this bike a low profile utility bike. With all the spring mud, this has been my preferred beater bike that I don't have to clean up afterwards. About 40 mins into my ride, the bike totally shuts down. I went through some of the connections to no avail. Had to cut short my ride. Once home I was able to measure voltages on my throttle and the output of the throttle varying with twist so it wasn't a throttle issue. It also signifies something quite wrong with the controller.

Last year I switch over to using a Topeak rack so I could interchange my batteries. I could run my Konions at 40 volts and my lipos at 48v. 50V is the limit of this controller due to the cap on board. I was running lipos today. Hopefully it's something minor. I have the controller apart, but won't know more until put my o-scope to it.

I also have the Nuvinci hub laced and will install it on this bike when I get more time. It's a high end part for such a bike but since the Nuvinci is rather heavy, this was the only bike I felt I didn't mind having the extra weight. It might ruin it's trail riding qualities though. Have to see how I like it.

I'm also switching over to tubeless this year. I've ordered Stan's no leak and will try the ghetto tubeless tire approach. I should probably post pictures of the bike as well.

[kfong]

Looks like pushing 48volts on this controller stresses out the voltage regulator. They seem to be using a transistor for the first stage. Q9 part KSP 42. Voltage coming out of it is way too low for the LM7815. Also the transistor is rather hot to the touch. Not sure if replacing it is a good idea, it's a rather wimpy part. I think I will modify this section with a dropping resistor and LM317.

[kfong]

Was able to repair the controller and put the bike back together for a trail ride before dark. Today was exceptionally warm for this time of year. I only wore a long sleeve t-shirt while riding. The bike is running good again. Fell asleep later in the evening from the workout. Really tried to make the 10amp pack last. Now I'm up an can't sleep. Here are pictures I took of the repairs I did.

The controller was removed and part was unsoldered. You can see the transistor in the middle of the board.

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I decided not to keep the original design since it would of burnt out again at 48volts. I was able to modify a board I did for my RC stuff years ago. Shorting out the first stage of the current section gave me a circuit similar to the circuits found on a lot of controllers using a resistor as a voltage drop and an LM317 to bring the voltage down. I chose aprox. 18volts for the first stage, giving the controller's LM7815 a voltage level it could work with.

controller repair1.jpg (77.53 KiB) Viewed 312 times

I ended up mounting it to the side of the box. I had to isolate the LM317 from the case by using a plastic sleeve and mica backing.

controller repair3.jpg (75.48 KiB) Viewed 312 times

For those running 48volts on this 24volt controller will eventually run into this problem. I have extra blank PCB boards available if you need them. $5 shipped. They are good for other low current applications as well.

controller repair4.jpg (102.95 KiB) Viewed 312 times

During the teardown, thought it would be a good time to see how the Nuvinci drive would fit. Looks like I will have to mill out the plate since it interferes with the rear derailleur. Not quite plug and play.

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nuvi3.jpg (62.14 KiB) Viewed 312 times

I also notice the motor having a slight offset. Took it down as well and discovered some damage to the frame. This is what happens when you start bashing into logs. Oh well, have to make a conscience effort to avoid the steeper ones. The mounting setup could of been better as well. It was designed around the first frame that broke on me. I might have to redo this part of it but for now I used a conduit pipe cut down the center and place over the damaged area. Hopefully it will give a bit more support against being crushed.

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frame damage2.jpg (93.54 KiB) Viewed 312 times

[kfong]

Here is the quick repair I did using electrical conduit pipe, grinder and hammer. I'll see how it does before I spend the time remaking the motor mount. It held up fine yesterday in the trails and I was rather hard on the bike hitting a few log piles that I should really avoid.

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Here is how the bike is currently setup. I lost the front fender and will be getting a new one. The controller has been resealed with silicone RTV and the smaller connectors wrapped in silicone self fusing tape to keep out moisture.

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current setup2.jpg (126.26 KiB) Viewed 303 times

Here it is all decked out for shopping and running errands. Not much to look at, but that's the whole appeal. I want a sleeper bike that performs, is reliable and still be fun. The only drawback is the original cyclone mounts are crap. You need to create your own or purchase better ones. The noise is also an issue, it's not as bad as an RC setup. For trail use the noise is noticeable to others, but for general street riding it's not bad and I prefer to make some noise when coming up on pedestrians. This bike goes 27-30mph with the 48V setup. Not bad for those not chasing after speed. It gets me to my corner grocery store faster then I can drive to. Gets hardly any attention, especially if I'm pedaling.

shopping setup1.jpg (115.52 KiB) Viewed 303 times

Here is the new front shock, RST Omni TNL with 100mm of travel. Cheap low end shock, but acceptable. Anything less I would find it hard to consider them shocks. It comes ready for front disks, so that will be an eventual upgrade on this bike since most of the stopping happens in the front. The previous RST 191 Omni CL had only a small amount of travel using a polymer cartridge, while fine for short trips. It totally sucked for trail riding and long distance. It would however, make a good front hub shock since it's steel and would take the edge off the vibration vs. a solid fork. If anyone is looking for a steel front shock for a front hub with a 1.25" steer tube that I don't think was ever cut down let me know. The frame has been holding up and is solid when jumping it. The trail reviews on the frame was good when I did a search. Geometry works well and the chrom-moly should last much longer than most bikes.

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[kfong]

Having switched over to Lipos, I needed a safe way to charge them. The only solution I felt comfortable with was to use a quality RC charger. The Hyperion was the one I felt was best designed. I then made a DB25 board to use as the balance plug. Here is the board attached to 4 6S 5000mA Turnigy packs. This setup is a 12S 2P configuration giving you 10ahrs at 48volts. The balance wires are just long enough to plug into the DB25 board. You need a second one at the recieving end of the charger.

DB25 board.jpg (64.93 KiB) Viewed 264 times

As you can see the board is attached to the end of the pack. The balance wires are just long enough to fit. There is enough room for my smart switch which would make this pack completely stand alone. Allowing me to let others use the pack without worry.

12S setup.jpg (64.41 KiB) Viewed 264 times

The bag used is a Topeak RX. It uses an integrated sliding mechanism for easy removal.

Topeak bag.jpg (85.44 KiB) Viewed 264 times

I padded the pack to protect the lipos

Padded lipos.jpg (55.14 KiB) Viewed 264 times

I balance charge during every charge, this setup makes it easy to do.

Balance charging.jpg (103.36 KiB) Viewed 264 times

I could of shortened the wires going from the charger to the DB25 board but the wire pattern is not 1:1. You would need to wire it, instead I just used short extension cables. I used ribbon cable for the connection between DB25 boards. This allows for hardly any wiring.

I still have boards available for anyone wishing to go this route.