newb not so ultimate commuter build

[dakh]

The internals swap between the standard Cutes and the H, but not the CST. Different width stators I believe.
Besides, moving a Cute from frt. to back doesn't change much.

After riding this rig a bit more I'm really jonesing for something a bit lighter and with better balance.

Like when you had a sm. lipo pack at the bottom of the frame?
Can you go back to it and only use the monster battery only when you need the range?

Bummer about CST not swappable, thanks for saving me some $$ trying I could do 16S pack with 201 wind I guess, or 10-12S with the high RPM wind and bump up the amperage, or use 26" rim with skinny tire.

In my mind no reason to use LiPo, if I'm going for a lightweight build I should be using Tesla cells sine they're twice more energy dense. Heck I could just split one of the packs I have, make one 14s2p and one 14s3p 14s2p would handle my current setup that draws 14A max just fine actually. Since I already have loose cells I have room to experiment, and I love me some DIY engineering. Look forward to posts documenting myself trying to fry all this equipment in the future

I will have to feel it to believe it on the front vs. back motor. So far my conclusion is front motor changes bike handling a lot, even with light battery it was already a substantial compromise. Maybe it's because the wheel build I'm using with the powered hub is more burly/heavy than a somewhat fancy/light hub/rim/spokes I compare it to. Instinct tells me I'd like rear wheel drive, battery weight near the crank a lot more. Of course no way to verify that until I ride one. I get substantial (and practical) air time on regular basis on my commute, so say I always use backpack over panniers and no super skinny tires. Having a heavy and not easily manageable weight on the bike makes me slow down for shit I usually fly over, which pisses me off.

 

[dakh]

What really is the hub interface on the 100H type rear wheel motor? I don't mind tearing up a 10 or 9 speed cassette and yanking 2-3 gears out of it, if the interface from cassette to the hub is compatible. Sounds like it's not, maybe there's an adapter available?

 

[d8veh]

You can't do that. A freewheel gear set is totally different to a cassette (freehub) set. It's not really a problem to use a freewheel set. 7-speed is adequate. Just get a new shifter.

 

[dakh]

You can't do that. A freewheel gear set is totally different to a cassette (freehub) set. It's not really a problem to use a freewheel set. 7-speed is adequate. Just get a new shifter.

Dang! Thank you for the education though. I have plenty of 9 and 10 speed chains, cassettes etc. This will just cause more questions, like: can you even use a normal 9 or 10 speed chain on that 7-speed weirdo?

 

[dakh]

..also, what kind of derailleur would work? Can I take a 9-speed and limit the range via adjustment screws?

 

[dakh]

Got some GPS tracker data from the phone on my commute.

Speed on the flats with mild pedaling is about 24mph. Overall average speed on a 13 mile commute with 1500ft elevation gain, 1300ft elevation drop, a bunch of stoplights/crossroads/sharp corners/potholes is 21.8mph. Not bad at all as far as I'm concerned.

 

[dakh]

Updates on the build:

1. Had to burn some holes in the rack bag and run a Velcro strap to make the battery more solidly attached to the rack. Otherwise the bike would handle too funky especially standing up and mashing -- it'd sway too much.
2. Bent the shit out of the rack itself so I think it's about not safe to use anymore at this point, will have to replace with a different design. I got this one because it was supposedly disc brake friendly but the frame has the caliper inside the rear triangle so I think I can use any rack really.
3. Wiped out trying to back it in on a gravel road the other day.. Keeping it pinned and having the front wheel pulling plus sliding with the rear brake works pretty good -- until it doesn't. I think the battery being so far back and up messes up the balance of the bike, so once lean goes above a certain angle, the back end just tries to fall in and front gets uncontrollable. Almost killed a perfectly good Chrome bike shoe trying to save that one by sliding it across the gravel.
4. Got into situations where I needed to park the bike in not so friendly places a few times so now really putting priority on an easily detachable battery and possibly controller. I think it'll be a Topeak MTX rack and bag but I'm concerned that I'm going to destroy that one too, so going to buy that at REI to be able to get replacements.
5. Once I get the detachable battery/controller solution figured out I will likely leave this one alone and start building another version, this time with a better battery storage solution, 17-20A controller instead of 14A that I have now, and hopefully rear wheel drive.

 

[dakh]

Oh yea. Will have to use something other than Anderson connector from controller to the battery, or figure out some way to secure it. Current one pulls itself apart a lot so I have to stop and re-connect. Not fun.

 

[striider]

Oh yea. Will have to use something other than Anderson connector from controller to the battery, or figure out some way to secure it. Current one pulls itself apart a lot so I have to stop and re-connect. Not fun.

I had that issue, but just had to extend the lead so it had more cable and room to move. Things seems to shift and move more than you think on these bikes. You could just solder in and heatshrink some more wire in between connectors to keep from having to add more connections.

As far as racks, Tubus makes all steel ones that are damned expensive, but at least you won't have to worry about it anymore. Doubt a topeak will hold up for you. I also bent an aluminum disc brake one to shit already. I got a steel rack with one of my kits I ordered, but the design is dumb, it goes all the way around the axle so you have to thread your wires through it and flat repair should be fun. The main supports were also too short for my bike so it would tilt back and try to jettison my battery, so I don't use it. Maybe I will get the welder going and add in an inch or 2 and weld a mounting plate to the proper rack mounting points. Currently I am using another aluminum rack that I had on my wife's bike that has straight supports down to the mounting points, but haven't given it a true weight test really. It carries a 20ah lipo with no issues so far though, and has carried a 25ah LiFePo for 28 miles.

Alternately, you could get rid of the heavy duty rack and bag dependency by moving your battery back to the triangle, where it should be. Here is the setup I use, and love it SO much better with the weight in the triangle. No reason not to use all of that triangle real estate imho. http://endless-sphere.com/forums/viewtopic.php?f=4&t=29211&start=200#p1057460

 

[dakh]

Thanks for your reply striider. As much as I like the simplicity of a triangle bag I don't see how that would fare well when I need to lock the bike in the city -- too much work to undo all the straps. And the bag itself is fairly expensive so taking contents out will still be a problem, someone'll yank the bag itself. So for off the shelf solutions I only see the latching trunk bag so far, or some custom contraption that mounts towards the bottom of the triangle.

I totally agree on trunk being a bad place for the battery as far as bike handling goes, but I just don't have time now to engineer and make a proper solution. Bike works great for me otherwise, been riding it all over so I'll keep improving it in small steps.

For Andersons, again the issue is I need to have some kind of quick disconnect coupling to be able to take the battery with me. If I leave the controller on the bike... Actually I don't really want to go there if I could help it. Not that I care much about $15 piece to be stolen, but the hassle of re-wiring stuff and waiting for replacement to show up would piss me off big time. So it'll have to be some fairly complicated connector, or maybe two - one for phase wires, one for the rest of the crap (hall, throttle, etc.). Any suggestions?

 

[dakh]

Well, I'm continuing to put the hurt on this thing and finding weak spots. Front wheel now is pretty well out of shape, can't ride hands-free without a pretty bad wobble. The $.02 connector for throttle fell apart again, got pretty exciting for a bit with it suddenly going wide open as I was slowing down for an intersection.

So far my conclusion is pretty much anything that does look like it'll fail, I manage to make it fail. So on to find some good connectors, on/off switch, new front rim

 

[dakh]

The story took a fairly unexpected turn here.

My package with new motors got stuck somewhere in HK so I was roaming around the garage figuring out how to prepare for when stuff shows up.

What came out is this. I had this Kona Rove frame which I stole the steel fork from, so I decided to transfer existing parts to that frame so that I can build up a rear wheel drive bike with carbon fork that came with the Coda.

I also got a Topeak MTX rack and bag so I needed to install that and see how that works out.


Well, while I was working on building up the new frame, and so not looking forward to dealing with derailleurs etc I realized that I could totally live with this thing being single speed.

And lo and behold, even though Rove frame is not a single speed frame, the chain length was literally spot on perfect for the 42T track chainring I had and 13T cog I stole from an old cassette. So a bunch of spacers later I now have a newly built single speed bike with removable battery.

Experiments show that controller is definitely not happy sitting inside the bag so now I need to decide if I want to mount controller on the bike somewhere and only have 2 wires to connect when putting the bag on, or mount controller on the bag and make some big connector thing happen that would do phase wires, throttle and Hall sensors in one go.

 

[dakh]

 

[dakh]

..so after I figure out the connection story and some sort of U-lock mount I'd be able to leave this thing locked up for some time without a bunch of hassle -- with the MTX bag it'll only take a push of a button and disconnecting a wire to be able to grab controller/battery and go.

 

[dakh]

One more beginner question: can I remove or lower LVC on those $14 elifebike controllers? These Tesla cells can go all the way to 2.5V without much problem, current cutoff at 41v is 2.93 which is too high. Those cells also don't die at even lower voltages so I'm quite willing to forego LVC altogether. I'll know the voltage is way down from the way the bike feels anyway so it's not that useful to me.

 

[dnmun]

One more beginner question: can I remove or lower LVC on those $14 elifebike controllers? These Tesla cells can go all the way to 2.5V without much problem, current cutoff at 41v is 2.93 which is too high. Those cells also don't die at even lower voltages so I'm quite willing to forego LVC altogether. I'll know the voltage is way down from the way the bike feels anyway so it's not that useful to me.

you could use a 36V controller that has the 30V LVC or you can go hack the resistor divider that sets the LVC on your current controller.

pushing large currents through a battery cell that is discharged to low voltage tears a lot of cycle life off of the cells.

 

[dakh]

you could use a 36V controller that has the 30V LVC or you can go hack the resistor divider that sets the LVC on your current controller.

pushing large currents through a battery cell that is discharged to low voltage tears a lot of cycle life off of the cells.

So 36V controller has the same guts and can deal with 58V? I just go by what the experts say about these specific cells I have, discharging to 2.5V (loaded) is Ok so ~35V LVC is ideal. Quote: 2.5 is minium for good cycle life, 2.8 leave a decent buffer .

With a 5p pack and 14A controller I'm doing a bit below 1C draw per cell, is that still "large current" for the purposes of cell life? Actually I guess the question I should be asking is how much useful capacity am I actually missing out on if I can't discharge that last .5V?

 

[dakh]

Getting close to done with this one.

Rode it a bit more and single speed setup works great for me. Good training to vary the cadence. Have to spin a bit faster than optimal on flats and stand up and mash on steeper uphills. The only thing, riding-wise, that isn't so great about this setup is the battery is so high it ends up producing a weird swaying feeling when mashing. Well, and of course if electric assist goes belly up it won't be very rideable on anything but flats with this gearing but I'm good with that, hopefully won't happen very often.

Also I got the battery charged to 4.2V/cell for the first time the other day, was charging to 4.1V before. I think the speed this bike gets at 4.2V/cell 14s is pretty much as fast as I'm willing to go for commuting purposes.

Decided to get the controller mounted under the rack rail. First I was thinking I'll just hard-wire everything and eliminate all connectors, but it turns out that wasn't necessary. So I just snipped all the wires I wasn't using out of the controller, shorted out the on/off switch wires, put a bunch of shrink-wrap on everything and called it good. Rattle canned controller housing in "shitty black" (c), so it looks delightfully unappealing now -- a very good thing in this case. So at this point I can U-lock the bike in the city, grab the bag off the trunk rail and go. One Anderson connector and it's done.

Few fit and finish details left but I'm pretty damn happy with how this turned out so far.

 

[dakh]

 

[dakh]

One more thing I did differently this time. Previous version had the battery pretty firmly tied up to the rack. This time I stuffed the bag with fairly thick foam padding so the battery has a bit of a suspension. That made a big difference in the way the bike feels when going over bumps and jumping, a lot smoother. Maybe Kona Rove frame is a bit more soft than Coda but I think battery suspension is key.

It only is made possible by the Topeak trunk. It is pretty darn stiff and with the plastic base that slides into the rack the battery doesn't wobble around at all.

 

[striider]

Super clean setup, I love it. I need a harder sided bag like that.

BUT: I have the same aluminum rack exactly. It bent where the three supports come together after a about 3 weeks of commuting and a good sized pothole. My battery weighs 13 lbs. I fear it's just a matter of time for you too. YMMV, but others warned me this would happen and I didn't heed the warning. No big deal since I was keeping an eye on it, but it could be when it cracks or contacts the rear tire....

I am currently using another rack I had laying around and putting off modifying a steel one that came with my wife's kit. THe rack I am using has straight supports down to the mount points instead of disc brake spacers (since I don't have discs). Also taking a look a long hard look at Tubus racks.

 

[dakh]

Thanks for the warning on the rack! My battery is 8lbs and I did put a pad between the battery and the rack, it's holding up so far but yea I don't dig the funky rack. I do have disc brakes but they're inside the triangle so it's not exactly necessary. Will keep an eye on it for sure.

 

[dakh]

Actually the worst thing the rack could do is bend the bike frame tabs. That would really suck. Gotta really keep an eye on it.

I'm running 700x28 tires, maybe also up the ante and get 32mm wide ones.

 

[dakh]

Came back here to check out what's new, decided to give an update on this bike build.

almost 3 years, probably 4 sets of tires, the thing is still going strong. I had to rebuild the front wheel since whatever crap build there was kept losing spoke tension. New set of spokes and a chubby Velocity rim, haven't had any problems at all.

The "raw" Anderson power connector still gives out a fat spark when plugging in, but it still works just fine.

Motor now has 260RPM gears and I'm thinking of getting 328's.

Still running the same 14s5p Tesla battery brick, same tiny controller -- all still work great. I'd say about 50 to 60-mile range with some hills.

Super happy I've built it.