Electric Bikes - What bike gets best speed with electric kits
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09-05-08, 12:57 AM
I'v been riding my 24v Synergy for about 5 years now and I'm ready to try my hand at kitting out a new bike. I live in Fresno so its pretty flat, so no great challenges there but I do want more speed and range. I am looking at Amped but trying to decide on a bike to put it on. I don't really want a 48v system because the battery mount looks cumbersome. I like Synergy's midframe mount and I'd like to stay with that type on the battery so it will probably limit me to 36v. I am also trying to make a decision on front vs rear hub. Front looks like an easier install, but what are the drawbacks?
My biggest question is: the Synergy is a 7 speed mountain bike and I pass most bikes on a regular basis, but every once in a while a non-electric paces or even passes me even though I'm pedalling along with the motor and they aren't pedalling any harder than me. Its usually someone that you can tell is an avid rider and has a nice bike and I'd kind of like to know what experience anyone has had looking at doing a kit based on a fast bike then looking at the motor/battery setup. If so what kind of bike would you recommend?
09-05-08, 10:57 AM
The fastest electric bikes around are usually based on POS walmarts or old junkers found at garage sales. Once you move over into electric, its not the bike that goes fast.... its the motor/batteries/controller.
If you arent dealing with lead acid cells you can fit quite a bit of power into the center triangle. In some of the early versions of my bike, I had 72v 20AH worth of batteries mounted in the center. Ive since moved to mounting them forward of center and off the side to better balance with the motor in back. Also im not sure if you've ever tried to carry an 80 pound bike without lifting from the cross tube, its a little on the hard side..... In short, dont limit your design opertunitys, it might turn out that there are better options then you think.
09-06-08, 01:57 AM
I have a Trek 700 cross training bike, half way between a road bike and a mountain bike. I was thinking of adding a small hub motor and Li batteries to that. Something like that might be what you are looking for. It is very light.
If you are constantly riding above about 25 mph, you need to consider the stress on your frame. I would be more comfortable on a sturdy mountain bike.
Use slick tires if you are mostly on pavement.
About front vs back, I like to lift my front wheel over curbs (mini wheeley), which would be more difficult with a front hub because of the weight, and no assist to help of course. Front wheels can slip going uphill on rainy pavement. Most of the time, there will be no difference. On rear wheel drive bikes and cars, the motor torque shifts the weight to the rear wheel(s), so it is probably better for getting out of the hole fast.
09-06-08, 01:00 PM
Another consideration for higher powered kits is that the front fork and dropout is not nearly as strong as the frame and drop out where the rear wheel is mounted. At the rear, the dropout is at the intersection of two frame members, while at the front, you are pulling on the end of a lever. With enough force the fork will break off.
With e-bikes, it may be wise to pick a bike that would be considered quite slow if it were a motor-less bike - you will lose less time to breakdowns if you pick a bike with strong and heavy wheels and tires, and with a stronger-than-necessary frame (at least the part where your motor attaches).
09-08-08, 10:38 AM
I'v been riding my 24v Synergy for about 5 years now and I'm ready to try my hand at kitting out a new bike. I live in Fresno so its pretty flat, so no great challenges there but I do want more speed and range. ...
I have no e-bike experience, but that's not a major factor here.
The best way to improve speed/range is to cut aerodynamic drag, and the most comfortable and practical way to do that is a long-wheelbase recumbent with a front fairing and body sock.
A long-wheelbase recumbent would be something like a Tour Easy (http://images.google.com/images?um=1&hl=en&safe=off&q=tour+easy&btnG=Search+Images). A Tour Easy costs around $2500, but there are other similar bikes for about half that much.
The front fairing is the Lexan bubble thing on the front, that you see in many of those photos. Figure $400 or so for the front fairing. Zzipper (http://www.zzipper.com/) and Mueller Windwrap (http://www.mueller-hp.com/) make fairings; prices and quality of products from both companies are generally held to be comparable.
A body sock is a fabric covering, as shown here: http://www.bentbodysocks.com/.
Ideally you would have a full hard fairing like on IHPVA record bikes such as the Varna Diablo (http://images.google.com/images?um=1&hl=en&safe=off&q=varna+diablo&btnG=Search+Images), but the cost and overall practicality of these shells leaves a lot to be desired.
A fairing+bodysock can be added to most long-wheelbase recumbents pretty easily, it provides most of the benefit that a full hard shell would and because the bodysock is soft, it has some "give" in crosswinds making it much easier to handle than any hard shell will be.
If you can't stand the idea of using a recumbent, then Zipper makes a fairing designed for semi-upright bikes--as shown in the middle photo here mounted on the RANS Zenetic: http://www.zzipper.com/
(-I don't know that Mueller makes a fairing that is applicable to any upright bikes, you'd have to ask them-)
The RANS Zenetic is a semi-recumbent, but I'd think that the fairing should also fit on an upright bike too. The base Zenetic msrp's for $1400, but the Fusion and base Dynamik models are around $1000: http://www.ransbikes.com/
The body sock would need a rear frame to attach to (you may have to make that yerself) and the material itself is just lycra fabric.
09-08-08, 05:26 PM
The number one thing you can do to improve speed.... switch out knobby fat tires to something slicks that runs around 32mm. I'd also get a steel cyclocross frame so you can put 700x32c slicks on there. You could go a little faster with 700x28c but they usually require 120psi and for electric bikes you'll want to max out at around 85psi (unless you're really good at avoiding bumps and potholes).
The cycloscross frame will also get you into a more aerodynamic position. Not quite racelike which is uncomfortable, but better than a mountain bike.
09-08-08, 10:06 PM
Thanks for all the suggestions. Top speed isn't my only concern, I am trying to find a balance in terms of good performance and ease of ride. I do want comfort too - but I want a faster bike than what I have now in case I am not using the motor. I have had a few occasions on my Synergy when I ran out of juice and pedaling was slow going. I thought the motor didn't create any drag, so I was wondering if it was just a slow bike. I know the battery and motor weight (not to mention mine - 5' 11" 225 43 yrs old) doesn't help
What about putting a kit on a fixed gear cruiser? Any thoughts on that? I've been doing some research and am leaning towards a hybrid - is that the same as a cyclocross?
09-08-08, 10:21 PM
Crystalyte kits with front or rear hub drive are well known. You can choose 24 to 72 volts. The higher the voltage, the faster you go, depending on the type of motor as well. The 5300 series, I think I got the numbers right, is probably the fastest. A 72 volt system with good batteries will do about 60 to 65 kmh.
I presently have the schwinn electric bike that comes with 24 volts and a currie 300 or so amp motor that's got brushes and stock it goes about 28kmh. I hooked up to 48 volts and now it goes 45kmh. The higher the voltage= speed.
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