Hello everyone.

I've decided that I would like to purchase or build and electric bike. I would like to use it for commuting a 25 mile round trip to work on completely flat terrain. I would have no problems charging it while on the job.

One of the few things I know about e-bikes is that whatever range you desire, you need to double it. Are there any e-bike out there with a 40 mile range? Most bikes I have seen seem to be in the 15-25 mile range.

Double the range? That's not a bad rule of thumb, in my opinion. Building your own is a lot more fun, plus you'll know the bike inside & out. Look for a kit (http://www.werelectrified.com) with at least 12Ah of battery capacity. My 13.5 mile commute (round trip) uses 2.6-2.8 Ah going to work and 1.6-2.2 Ah coming home, according to my DrainBrain (http://www.ebikes.ca). (I'm pedaling much harder coming home but usually have a significant headwind. I cruise at 19mph going in and 22-24mph coming home.) Figure you're going to need perhaps 5-6 Ah each way. Charging at work is a good idea, otherwise you're going to need a big battery pack for a 40 mile range at a decent speed.

I recharge at work, too, but designed my ebike (http://www.captmonkeyrocket.com) so that I don't have to. Still, it's easier on the batteries if I do, so I do. The only extra cost (to me) was for a 2nd battery charger.

The new Giant Twist 2.0 is supposed to have a 40+ mile range. Sadly it's only available in Europe.

My homebuild travels 48kms a day round trip.

If you have a good doner bike, (http://www.crazyguyonabike.com/pics/crazyguyonabike/docs/00/00/21/73/large/giant01.jpg?v=O) it should not be a problem.

I believe the o.p. was basing his 40mi needs on the observation that (lead) batteries don't like to be discharged anywhere near capacity. By having only 1/2 discharged batteries at the end of the commute s/he is preserving battery life. However, only lead batteries need to be babied this way and for this and other reasons I can't recommend actually trying to build a 40mi SLA system but instead build a proper 25mi Nimh or even Li system and call it good. I must admit I am confused by the way Ah are used by battery manufacturers and one of the previous posters in this thread. Are Ah a unit of capacity or expenditure and if they are a unit of expenditure shouldn't a measurement be an absolute? In other words how can poster X use "1.6ah - 2ah" on their return trip? In what amount of time over what distance? Does it matter? If a battery has 12ah capacity can you simply subtract ah units of consumption from it, if so why aren't motors rated for the ah they will subtract from one's battery over X unit of time?

H

Hello everyone.

I've decided that I would like to purchase or build and electric bike. I would like to use it for commuting a 25 mile round trip to work on completely flat terrain. I would have no problems charging it while on the job.

One of the few things I know about e-bikes is that whatever range you desire, you need to double it. Are there any e-bike out there with a 40 mile range? Most bikes I have seen seem to be in the 15-25 mile range.

What is your budget, and how often are you going to ride? What type of bike are you thinking of converting?

Check out www.ebikes.ca and try the hub motor simulator out to get a feel for speed and power requirements. A 406 hub at 36v, or 408 at 48v are good choices for legal speeds.