KMX E Cobra

[greenerwheels]

Back in April I bought a KMX Cobra from FFR. Tommy treated me right and I got the trike very fast. Well right after I got it, my wife was diagnosed with Breast Cancer and pretty much all activity stopped on the bike before it got started. My wife is doing much better now and I've finally gotten to the point where the bike is almost road ready.
A few corners had to be cut for financial reasons, but its on the road. I'm using a Crystalyte 408/411 motor on a 26" rim with a Maxxis hookworm tire, the bike comes stock with a 24 inch wheel, so I was a little concerned about fitting the 26 inch wheel with a massive hookworm tire but it fit with about 3/4 of an inch to spare.
The bike is powered by 4 Bosch fat packs, 2 more to come later, I retained all of the original battery and can disconnect a battery from the pack and slide it right into my drill when I get to where I'm going. I really like the idea of being able to multi-task my battery packs. And the Bosch drill is a monster. The pack is clamped on to the frame. Each pair hangs off the side and are clamped in place.
I've taken it up to 35 mph in my neighborhood on a slight downward grade. It feels like a rocket on rails. Yesterday I a few hours riding around the neighborhood doing donuts. Oh the stock bike comes with a dual brake on the right bar (for both left and right front wheels) and a locking brake for the rear. Since my hubmotor doesn't have a disk I took off the rear brake and removed the right side dual brake lever and replaced the two brake levers with two standard brake levers controlling the left and right disk individually, the brake cables are very short and react better than any bike I've ever owned. The beauty of individual control of left and right front wheels, so its a lot of fun cutting a turn while braking in the direction of the turn. Power slides are a blast on wet surfaces (like yesterday) however today wasn't so wet and my wife and neighbor were outside talking while I decided to whip around the corner and slide on past, only there was no slide just me and the bike rolling over in front of them. The bike came out better than me, no taco'ed wheel, no scratches to the paint, just a nice road rash on my arm, strange for a minute I thought of every cut scrape and bruise I did to myself when I was 12, Right on! Any there are a few things that need to be changed and I really can see the need for a torque arm. But I had to take it out for a ride. I also really want to say thank you to Tommy and FFR for treating right and getting me the bike of my dreams anyway have some pictures.

 

[AmpEater]

Wow, that is incredibly clean looking. Those packs are right at home there. Very well done

How twitchy is the steering at higher speeds?

 

[greenerwheels]

Its not twitchy at all, The bike fly's straight and mostly goes where you point it. I'm thinking I'll save the stupid stuff for when the roads wet (which seems to be most of the time here anyway) I don't think a Catrike or a TerraTrike would have survived the roll I did today, of course the KMX was made for crazy stuff.

 

[USAEBIKECO]

wow that recumbent is awsome! I bet its so fast.

 

[knoxie]

Really nice build there!! well done it looks almost like an off the shelf bike, very nice indeed, I havent been on mine for over a year must have a whiz about on it at the weekend, hope your wife is on the mend too thanks for sharing.

Knoxie

 

[zap]

What a nice clean looking vehicle.
The way you did the batteries looks like something from the factory.

 

[greenerwheels]

Commuted to work today on my Cobra, 5 miles each way, consumed about 2.8 Ah each way. I tried using imapmyride app on my iphone, but managed to get as the crow flys route so somewhere I screwed up a setting. I'll try again later. I also mounted a pannier on the left side and put a larger uglier flag to be better seen. Commuting on a tadpole trike is an interesting experience, low to the ground even Honda's seem tall, only came across one driver that thought the white bike lane stripe was an alignment guide. F350's are exceptionally tall when they drive past within a foot. I'm running 4 Bosch fatpacks, I'm thinking 2 or 4 more would give me more headroom and allow me to modify the controller for more current, got home with 34.8 volts available, I did both legs without charging at work. Anyone know where I can find a big, 4 hole chain-ring for the front? Currently I've got a 44 tooth ring and pedaling is useless when the motor is up to speed, I think I'd like a 58 or 60. I had removed the front derailleur and shifter to install a throttle. I have quite the box of unused parts from this bike. The Crystalyte hub probably needs the spokes tightened, I haven't yet found a spoke tool large enough and my kit didn't come with a tool. Overall the ride was a blast, I'll try to ride again on Thursday and figure out imapmyride or replace it with something better. Next additions with be a Iphone mount and a left side mirror.

 

[adrian_sm]

First off, great looking bike you have there. Really neat installation.

As for chainrings, here is a list I made for myself when searching for the biggest, reasonably priced chainring for my mountain bike. Hope it helps.

# teeth / $ / Link
50T 104 £46.99 http://www.chickencycles.co.uk/index.php?cat=32&ord=0
48T 104 http://www.middleburn.co.uk/chainrings_mtb.php
50T 104 $58 http://cycleunderground.com.au/chainringdesigns.htm
48T 104 $22.60 http://www.chainreactioncycles.com/Models.aspx?ModelID=19105
48T 104 $38.15 http://www.chainreactioncycles.com/Models.aspx?ModelID=5700
48T 104 $56.52 http://www.chainreactioncycles.com/Models.aspx?ModelID=19103
48T 104 $35.32 http://www.chainreactioncycles.com/Models.aspx?ModelID=38186
48T 104 http://www.bikeparts.com/productsearch.asp?categoryName=Chainrings&manufacturerName=&selManufacturer=&selCategory=1361&strSearchString=48T&displayName=48T
48T 104 $32 http://www.bikeparts.com/search_results.asp?ID=BPC123428
48T 104 $25 http://www.vueltausa.com/products/chainrings/flat-chainrings.htm
http://www.hostelshoppe.com/cgi-bin/search.pl?category=605000
52T 104 $40 https://www.jrbicycles.com/storefront/index.php?act=viewProd&productId=2127

- Adrian

P.S. Make sure these are the right size for you before ordering. If you want to go bigger, some of the blokes around here made adapters to go from a MTB crank to a road chainring which come in bigger sizes.

 

[greenerwheels]

Adrian: Thanks for the list, The last line one, the 52 tooth RENNEN Chain Ring from jrbicycles sounds closest to what I want. I might have to try to hack my own.

Thanks again

Greenerwheels

 

[devorion]

That's a very perty looking bike you have there
if you want a larger chain ring but the option of a smaller chain ring too without a derailleur to shift between, you might want to have a look at the Schlumpf High Speed Drive, first hit on a google search will find you here http://www.utahtrikes.com/ARTICLE-33.html which is quite informative. similar weight and a slight modification needed to the bottom bracket, or in your case.. the top bracket?

nice ride

 

[Ypedal]

Very cool !!!.. I almost got one this year but it was out of budget.. next year for sure..

You will love 72v on that motor in 4011, if you like the current 36v( i'm assuming you run in 408 most of the time now ? )... it only gets better with more ( even 48v peps the clyte motors up quite alot !

 

[greenerwheels]

With my new acquisition of 6 more fat packs from etard, its time to bend more steel. I haven't been able to bring myself up to welding on my Cobra, so all my add ons have been done with the fabrication of brackets. I mocked up the addition of two more batteries on one side but I'm not sure how to address the other side as I added a pannier mount so I could carry my lunch and other assorted stuff I need when I commute to work. I've got some concern that my analog Crystalyte controller might not be up to 2s4p bosch packs when they are hot off the charger. I need to open the controller up a see what the caps are rated and consider a fan for cooling. Anyway other than the dorkie flag my wife insists I have on the bike, I'm pretty happy with it so far. I also noted with the hook worm tire in the rear interferes with the chain, keeping the last two gears unusable, I guess I'll have to find a narrower tire, not that I pedal all that much.

 

[jmygann]

Did you use the original cassette from the cobra ?
Any reason you went from 24" to 26" tire ?

 

[greenerwheels]

The choice to use a 26" wheel and tire was purely financial, I broke the bank buying the bike and already had the hub motor, plus I ended up getting a smoking deal on a new Hookworm for $20.00 from the LBS. The freewheel on the bike is the Shimano 7 speed that came with the Hub motor, turns out I can't use the two largest chainrings because of the width of the tire, otherwise the rest of the SRAM components don't seem to have a problem working with the freewheel. Currently I'm working to insure the additional fat packs I'm installing don't interfere with the derailleur. I'm trying to keep the additional weight close to the lines of the bike to maintain handling.

 

[docnjoj]

I just saw the Fatpack mount on the trike and it is sensational. I stacked mine vertically with three on each side but the Lexan holder came out looking poorly. Strong though. Thanks for the inspiration. I got my front wheels from FFR. Good folks.
otherDoc

 

[geoff57]

Hi
I readying thread through with interest, I am about to start building up my third kmx I learn a lot with each build, the first was chain drive but needed too much maintenance, chain drive systems have improved a lot since then though. My second was with a hub motor a puma lots of power but the speed was limited by the cogs in the motor as it was a geared motor, lots of fun though and a lot less maintenance. For my third build I have gon for a real workhorse a 5305, I was going to relace it into a 24" rim but after reading this thread I will stick with the 26" rim that came with it and a pick up a 26" hookworm. Btw what size of hookworm do you have the 26 x 2.5 size.
I see that you use a half grip throttle how do you find that I was going to use a thumb throttle but my mind is not set yet.
I agree with doing away with the rear brake and going for independent left and right braking, I will be using an infineon controller and making use of the regen for rear braking I will have the regen on a switch so it will not activate always when I pull a brake.

Geoff

 

[kmxtornado]

OMG! That's the cleanest KMX ebike I've ever seen! FFR has come a long way the past year in their builds! I talked to them briefly too about modding my own KMX Tornado, but the price was just a bit high beyond my budget. Cool to see that someone actually did it though! Must be soooo much fun. I'm way jealous.

Sorry to hear about your wife. I hope things are going a bit better at least. She knows you're out having fun at least. Honestly though, take care of you and your family. It's a tough world out there. Enjoy each other's company while you can.

On a brighter note, here's a picture of my super jealous KMX wishing it was an electric 50mph demon. It's so far clocked in at around 37mph going downhill buzzing down at 72 gear inches. On the flats I've gone about 25mph. Sweating for sure.