Full suspension Kona build, need some advice!

M

matt912836

100 W
Joined
Nov 25, 2012
Messages
126
Location
New York
I recently purchased a Kona Kikapu FS frame of CL to build my next ebike on. Came with a Fox rp23 rear shock. I chose full suspenison because with past experience, anything faster than 24mph on a hardtail is uncomforting hitting the slightest bump. I also want the ability to do some very light off roading and have no problems hopping off curbs and not having to baby the bike. With this setup I am planning to use 4-6 36v 4ah batteries mounted in the triangle. How they are wired depends on which route I take on the motor. I want this setup to have good low end torque, and a top speed of 25-30mph (don't see the point of going FS if any slower). I'm also looking for the most efficient setup possible to maximize range. I DON'T want to throw thousands of watts into a motor, 500-1000 max, so it will definitely have to use the efficiency of using gears. Not trying to bust the bank either, this is a budget build. With that in mind, I'm looking at two options right now:

[strike]A brushed geared mid drive kit:
http://www.ebay.com/itm/24V-350W-DIY-MTB-Electric-Bicycle-Accessories-Kit-Geared-Brush-Motor-Conversion-/151872590818?hash=item235c4fd3e2:g:cCEAAOSwKsRWFhCu&vxp=mtr

Or, a brushless geared hub motor:
http://www.ebay.com/itm/36V-500W-Geared-26-Front-Rear-Ebikeling-Electric-Bicycle-Conversion-Kit-ebike-/271923152076?var=&hash=item3f4fe204cc:m:mDQBWD22DB6VOvwhv_g145g

For the brushed kit, I chose the 24v 350w version since it will spin faster at 36v than the 36v 350w version. I don't care about noise, if anything I'd rather you hear me coming when I'm at speed than be silent. Hopefully that will get me somewhere in the 25+mph range, as its supposed to do around 20-22 stock. Since its a mid drive it will inherently have lots of low end torque in the right gear, do you think I can acheive 25mph+ with a 24v motor @ 36v in one of the highest gears? Ill wire all the batteries in parallel with this setup and about 500w. Only thing about this setup is the way the motor mounts to the bottom bracket, the rear suspension pivot is right above the bottom bracket and might get in the way and require slight modification of the mount.

If I chose the brushless kit, I was planning on swapping out the stock 36v 500w controller with either a 72v 500w or 72v 800w controller to acheive a higher speed. I wouldn't want to go past 800w on this 500w motor to avoid any burning out issues. How would this motor perform with double the voltage with the same or a little more wattage? Since its geared and higher RPM's are always better with geared I assume it would have better low end torque and a higher top speed with around the same amount of wattage, just bumping up the voltage and trying to keep the watts under 800. One thing i did notice is the dropouts on the kikapu are very small and circular, no "flatness" or "deepness" to hold the flat part of the hub motor axle firmly, what can I do about this? I'd assume i'd need torque arms if i plan on going to 72v even if it is less than a thousand watts. Could someone recommend torque arms that would be good for the kikapu?

Any input is appreciated![/strike]

I've decided on a mid drive approach, this mid drive kid by SBP seems to fit the bill at a decent cost:
http://www.sickbikeparts.com/catalog/product_info.php?cPath=26&products_id=180
Has a 36-72v external controller vs the internal in the bbs02 that can't go past 60v.
Also seems to be more adaptable to my frame's bottom bracket.
 
you seem to be confident with ebikes but I don't understand why bother with the very cheap brushed mid-drive kit.
If you want a cheap mid-drive get the popular cyclone 3000w(350$) and use lower amperage to maximise range.
At low power it will be more reliable than what we usually hear from this mid-drive.

The bike seems great (I got a cannondale scalpel with bbs02) but why waste your time on very cheap ebay kit when there are better options for a little more money.

I have no problem with your choice of cheap hubmotor, but the mid-drive is harder to install(kind of) and will be a pain to repair if broken because of the custom mounts.

Either get a hubmotor and torque arms (check out ebikes.ca) but the cyclone seems to be what you want.
 
Kikapu is a great bike. I have a Kona Stinky Ebike I've been riding for 9 years, which is like the Kikapu's older, bigger, steroid using brother. They make very strong, capable bikes that can be run anywhere.

As fredfire points out, The brushed motor makes no sense. You want efficiency, and that will have none. Brush motors are 1990's tech. we've come a long way since then.

And you aren't going to hit 30+ on a 350w motor without melting it. it takes around 1000 watts to go 30mph. Your motor will need to be capable of sustaining that. Many 500w motors could do it for the length of time your little battery would power them.

The second motor isn't going to take more than 48 volts. Mine protests loudly with extra gear whine at just 44 volts. expect it to melt at 72. It will start struggle above 20mph, and higher speeds are going to destroy it. I have one. I love it, but it's not a fast or powerful motor. It's very much a street only motor.

For what you want, there are 2 good choices. The BBS02, or the MAC
 
How about this kit instead? http://www.sickbikeparts.com/catalog/product_info.php?cPath=26&products_id=180 Seems like the lowest cost quality brushless mid drive, and motor is rated at 800-1600w so there's plenty of headroom for power. Only thing I am worried about is installing the left side motor mount on the bottom bracket. This picture of the kikapu shows what I mean, the rear suspension pivot sits sticking out right above where the mount goes around the bottom bracket. On the chain ring side its just flush enough that it wouldn't interfere, but on the left side it definitely would get in the way what looks would be a good cm or two. Would it be possible to just shave down whatever gets in the way on the mount with something like a grinding wheel on a dremel? Its aluminum

$_86.JPG
 
Wish I had your bike, but I wouldn't want any bike built to your plans.

Or rather, not if I wanted what you want. I'm not going to sugar coat this. You just need to understand a few things.

1. You aren't pedaling any at 30 mph. The bike is not geared for it. And it might be impossible to put larger front gear, because it will rub the chain.

2 but don't worry, at 30 mph, all you can pedal hardly matters at all for efficiency. It's like 10% at best, of the 1000w or so it takes to go that fast.

3 speaking of wattage, forget being efficient in any way at 30 mph. It just takes power to bull through the wind. No getting around this on an MTB. But if you limit the controller to 20 amps, and go to 72v, you'll have a bike that runs at 1500w max, and can reach about 35 mph. A better result might be to stick to 48v, but use a 40 amps controller. (2000w) It will top out at 27-30 mph depending on the motor winding choice, but have great take off. The 72v 20 amps setup will still be a bit sluggish leaving a stop. And, a 48v setup is all you need to cruise at the fastest speed your bike will be able to pedal. You can do a bit better stretching your efficiency by pedaling briskly at 23 mph or so. Now your pedal wattage is more like 30% of the total.

4 So don't buy the 36v hub motor. Get the 48v direct drive kit, which comes with a 25 amps controller, then swap for a 40amps when you have a battery that can hack the 40 amps controller. BTW, those cheap 48v kit motors can tolerate 2000w ok, and in any case at 48v it would run at full speed cruise on about 1000w. As for the brushed mid drive, forget that!!! If you want a mid drive, get a modern one like the BBs02.

5 re the geared motor, that is not a 500w rated gear motor that can take 1000-15000w. It's a 350w rated motor pushed to 500. get that only if all you want is a bike that goes 20 mph. But you could get a Mac, or similar 500w geared motor. They stand up well to 1000-1500w use. That would be a controller in the 48v 20 amps, to 48v 30 amps range. But if you really want to cruise at 30 mph, the faster wind direct drive motor is the thing. They can be found in "48v 1000w" kits very cheap.

6 The battery sounds adequate, but 12-16 ah of 48v is what you need. Unless you want to go 40 mph, then go to 3000w, 72v 40amps.
 
I realize 30mph is far from efficient which is why I wouldn't be cruising at that speed. Maybe I wasn't clear with my goals for this bike. I definitely won't be cruising at 30mph all the time with it. I'll most likely be cruising around 20-25mph the most of the time. I don't even like how it feels going faster than 25mph, being only 120lbs it feels like I'll be tossed over if a hard wind blew at the wrong time. I just want the ability to go jump up to 30 if needed in traffic or something or if I needed to get somewhere a little quicker, just to have that headroom.

I don't want a 30mph bike to run it at 30mph all the time, not only is it super inefficient with wind at that speed, but I also know constantly pushing a motor to its max speed continuously is also not the most efficient thing either, which is why I would want it to be 30mph capable, so my 25mph cruise won't be even close to pushing limits. Basically I don't want to have to full throttle to achieve my cruising speed. I want higher top speed more so that when my batteries are less than 50% charge I can still go 25mph.

I plan on sticking with 36v. The batteries I'm using allow a modular installation of 36v 4ah packs (42v fully charged). This allows me to place the batteries in the triangle in different configurations to have the most space efficient way possible rather than having to mount one giant pack somewhere. I can throw 3 in the triangle if I don't need much range for 12ah and want to save on weight, throw two more in parallel if I want more range for the day. Each 4ah pack has a 60amp fuse and each single cell is rated at 22amps. It's a 10s2p pack so to me these are strongest safest pre made modular lithium packs I can find without having to go Lipo. These put out lots of amps like Lipo but without the Lipo dangers. I've overcharged these packs, over discharged them, shorted them more than once by mistake, I even had one pack which had a cell that was punctured from shorting out the terminals on one pack to the shell of a cell in another. I've abused these batteries beyond belief and never dealt with any fire. Had I done any of these things with Lipo I definitely wouldn't have been so lucky. 3 or 4 in parallel could easily do 60a continuous. Not that i ever plan going past 1000watts, but once again that headroom means I'm never stressing the batteries. (Buying new batteries for this build, not using over abused punctured cells in this build! Those batteries were stolen along with my old ebike)

With that being said can anyone recommend or have experience with the SBP mid drive? I already considered direct drive for its simplicity, reliability, and durability, but they are not the best with stop and go commuting which is something I'll definitely be doing (I live in NYC). I also simply cannot imagine putting 22 pounds into the rear wheel. An 8 pound geared brushed motor mounted in the rear made jumping curbs uncomfortable. I definitely still want to maintain the bike feel and 8 pounds mounted in the middle vs 22 in the read is a worlds difference. I feel direct drive is better when you constantly want to go 30-35+ and have tons of battery to throw power at it. Along with a beefy frame and 6-8" of suspension. At that point I'd consider that more a lightweight motorcycle with pedals than a high speed electric bike. Definitely want to build one of those one day, but for now I'm aiming for as normal a bike feel as possible.
 
everybody will recommend a known mid-drive , the bbs02.

I suggested the cyclone because recently lunacycle got it'S hand on and you'll have usa support if it fails.

unless you get one of these, get a 1000w direct drive hubmotor and size your controller and batteries accordingly (it can be on 36v).
 
Can you please specify what batteries you are discussing. A link would clear that up.

Mid drives are the less developed more complex option for an ebike. Consequently, cheap ones like gng and cyclone tend to also require modification and fanning about. Each to their own, but too much hassle for me. I prefer to ride mine than play with it.

Alternatively there are more refined products. Bafang and tangent Daves mid drives are perfect examples. But be prepared to spend more for a better product. With the power you want, tangent Daves mid drive would be what I would be buying together with a 25r batt most likely from Luna.
 
I think you would benefit by going back to the drawing board and work backwards, forgetting about the kits and batteries you have already looked into for five.

Make solid decisions about what you need starting with speed and unsprung weight, decide on hub vs middrive. Now choose your kit. That will determine your voltage and current requirements.

Then choose your battery. This should be rated about what you need in terms of capacity. Voltage and current output should match the kit.

Done.
 
I got a bit confused by your first post.

You mentioned 25-30 mph, the need for it to be full suspension to go that fast, etc. I definitely got the idea you wanted to cruise at 30 mph.

Then start talking about 36v 800w, which in general, gets you to more like 25 mph at the very most, speeds at which you may not need full suspension at all.

Then you say you are considering a 350w kit, which will struggle to go 20 mph. Hell, with the wrong winding, it might top out at 15 mph.

Now that you clarified your needs, BBS02 if you want to reach 25 mph on 36v. Not one person on this forum is going to advise any brushed kit. Unless you only want about 15 mph.

On 36v, you won't reach much more than 22 mph with a larger 500w geared motor like the Mac, in 10t winding. I DONT recommend a faster winding Mac, in a large diameter wheel running 36v. That would ride very sluggish and have terrible efficiency leaving stop signs.

That leaves only one option that even gets close to what you want, a bbso2 kit. And to reach 30, you'll be pedaling your ass off. More like a 25mph max bike. Which doesn't really need FS unless for off road.

IMO, you are still kind of in the attitude of "this is what I want" 36v. So you gonna have to accept what 36v can do. It should be fine though, a decent 25 mph full suspension bike is still a joy to ride. 25 mph cruise is plenty fast really. You may even come to prefer about 20 mph, simply because it hugely increases the range you have.

I test rode some nice bikes at interbike this year, with the bbso2 on them, running 36v. I think you will be happy enough with that, unless you really do want 30 mph some of the time, for that, 48v.
 
At this point I'm kind of sold on mid drive. I definitely have considered a bafang, but $550+ for just a motor kit is kind of high for me. How does the SBP kit compare to a BBS02?
http://www.sickbikeparts.com/catalog/product_info.php?products_id=180
For the price of a BBS02 I can get this kit instead AND two 36v 4ah batteries for around the same price.
The only difference I can see is the BBS02 has pedal assist, and an LCD to set parameters. SBP controller is programmable but not on the fly. The motor seems like it can take a little more power than the BBS02 though? "650~1680W", so it shouldn't have a problem doing 1000w for a extended period if not continuously, which is more than enough power for me when used through the gears. Much better in my opinion than shooting thousands of watts through a hub motor. One of the comments says he gets 30mph in the second to last gear, not even the last one, this is on 36v.
 
I contacted SBP and seems like the issue with the rear suspension being in the way can be simply be solved with some spacers they have for the bottom bracket. What I also like about the SBP kit is the controller is external, runs from 36-72v. That gives me many more battery options. 72v through the gears should be interesting even with a lower 15-20 amp limit. 72v in the lowest gear should produce some serious torque. With a properly aligned drive train and in the right gear, shouldn't this be even torquier (is that a word?) and with a higher speed than running 2-3000w thru a hub motor?

BTW, the batteries I will be using are the greenworks gmax 40v 4ah batteries. $90 each. 10s2p of High power 18650's with built in BMS. 4 provide a pretty decent range (36v 16ah), I plan on running 5-6 for 20-24ah depending how many I can fit in the triangle with the cases removed. Yes, you can probably get a higher voltage 48v pack at 15-20ah for the same price or maybe even cheaper, but I prefer the modular approach rather than having one giant battery. Something goes wrong with one cell in the big battery, it'll be a pain. With these you can replace or remove one 4ah brick that might go bad or if you feel it pulling the whole pack down. And mounting one big battery can be a hassle, i can throw 4-6 in the triangle in different configurations. More in a saddle bag or top tube bag if i feel the need. Plus one of these alone can put out 40-50 amps (they have a built in 60 amp fuse), a few in parallel im pretty sure can do 100+ amps easily. Strongest safest chemistry you can go without going lipo. I've overcharged these bricks(one time to 44v), undercharged them(mid 20's), even punctured a cell or two on these, and still never had any issues with fire or puffing or even a major performance decrease. Probably a good amount of luck involved too :lol:
 
matt912836 said:
At this point I'm kind of sold on mid drive.
Matt, I'm interested in how your middrive worked out. I put a BBSHD on a Kona Kikapu a year ago, but I took it off. Even though I didn't ride hard at all, the deflection of the bottom bracket made me scared the lightweight aluminum frame would break. What has been your experience?
Click to expand...
 
You must log in or register to reply here.

Similar threads

N
experiment 36v battery on 48v 13A TSDZ2 kit.
Replies
12
Views
682
neixian
N
B
New TSDZ2B install issues: 2022 Rockhopper Sport L
Replies
10
Views
440
Bbbbrass
B
Reid_in_QC
Need help identifying Bafang geared hub motor BFY804B11346
Replies
2
Views
347
Reid_in_QC
Reid_in_QC
E
Help understanding / replacing controller please!
Replies
14
Views
1,367
encore-moi
E
T
recycles-ebike.com opinionss? anyone bought from them?
Replies
2
Views
369
tlam
T
Back
Top