Search found 4073 matches

by Jeremy Harris
Dec 01 2007 2:55pm
Forum: E-Bike General Discussion
Topic: Human/Electric hybrid velomobile?
Replies: 54
Views: 7684

I've done some quick drag calculations and it looks like the penalty for having exposed wheels(albeit fitted with discs) is pretty small, less than 5% drag increase over enclosed wheels with open wheel arches. Having a flat composite beam spring will help. I've already made a semi-elliptic carbon co...
by Jeremy Harris
Nov 30 2007 4:18pm
Forum: E-Bike General Discussion
Topic: Human/Electric hybrid velomobile?
Replies: 54
Views: 7684

Malcolm, I'm thinking along similar lines. I'd feel too vulnerable riding around in something as low a conventional recumbent trike, so would prefer something that's around the height of my SWB recumbent bike, which has a seat height that's around the same as that of a small car. Having a high seat ...
by Jeremy Harris
Nov 29 2007 1:21pm
Forum: E-Bike General Discussion
Topic: Human/Electric hybrid velomobile?
Replies: 54
Views: 7684

Some thoughts on regen: As I understand it, typical BL controllers just shut off all the FETs at zero throttle. It should be possible to just fit a three phase rectifier to the motor, with it's output only switched on when the throttle is at zero. One other snag is that the motor will most probably ...
by Jeremy Harris
Nov 28 2007 4:30pm
Forum: E-Bike General Discussion
Topic: Human/Electric hybrid velomobile?
Replies: 54
Views: 7684

Brilliant! The one in the lower pictures is parked next to the wooden car I linked to earlier, which means it has to be here in the UK somewhere. It looks like it's made using "stitch and glue" ply, like some small boats. I shall do some more digging and see what I can find - I already have a contac...
by Jeremy Harris
Nov 28 2007 1:26pm
Forum: E-Bike General Discussion
Topic: Human/Electric hybrid velomobile?
Replies: 54
Views: 7684

Many thanks for this, Miles. It looks like someone has had this idea before me! Still, at least it shows that it has some merit. I agree about the lack of an inverse Speed Drive, that would really be better, as the 2.5:1 jump of the Mountain Drive is a bit much. It would be possible to use the Speed...
by Jeremy Harris
Nov 28 2007 12:35pm
Forum: E-Bike General Discussion
Topic: Human/Electric hybrid velomobile?
Replies: 54
Views: 7684

I've been having more thoughts on this. I have a Prius, which has a limited engine rpm range, essentially just five stepped speeds at it's most efficient, as it uses a modified Atkinson cycle. On it's own, this engine would not be driveable, due to it's poor power delivery curve. In many ways this e...
by Jeremy Harris
Nov 22 2007 5:09pm
Forum: Battery Technology
Topic: Two Interesting New Lithium Breeds At BatterySp.
Replies: 19
Views: 2439

These look to be German Gaia AKKU cells. See here for the full range: http://www.gaia-akku-online.de/ENG/SEIT ... dukte.html

Jeremy
by Jeremy Harris
Nov 19 2007 3:01am
Forum: E-Bike General Discussion
Topic: eLation V2 Pictures now on web
Replies: 74
Views: 9854

Guys, It might be worth bearing in mind that many people in the market for an ebike or kit will surf the net to do some research. The chances are they'll find this forum, as I did, and read this stuff. My advice (which is only worth what you paid for it) is that airing commercial grievances on a pub...
by Jeremy Harris
Nov 17 2007 3:21am
Forum: E-Bike General Discussion
Topic: Full suspension VS no suspension
Replies: 28
Views: 3190

For really big bumps, then I doubt that there's any significant difference between a the energy loss from a suspended bike or a rigid frame. However, when looking at the very small deflections from uneven road surfaces etc, (which is what I was referring to, as it represents the vast majority of rid...
by Jeremy Harris
Nov 16 2007 3:32pm
Forum: E-Bike General Discussion
Topic: Full suspension VS no suspension
Replies: 28
Views: 3190

First the wheels leave the ground termporarily (expending energy lost) For energy to be "lost" (in reality just converted to another form, most likely heat) work needs to be done. The bike just jumping up a bit in the air won't do much work against the air around it, so little energy will be lost. ...
by Jeremy Harris
Nov 16 2007 1:26pm
Forum: E-Bike General Discussion
Topic: Full suspension VS no suspension
Replies: 28
Views: 3190

The suspension power loss isn't from the drive, in the main (so called "bobbing loss") it's from the deflection of the suspension itself and the energy that it absorbs from bumps. The really easy way to show this is to ride an air shock bike hard over some bumps then feel the heat in the shock. That...
by Jeremy Harris
Nov 13 2007 12:22pm
Forum: E-Bike General Discussion
Topic: Human/Electric hybrid velomobile?
Replies: 54
Views: 7684

Michael, During lunch today I did a bit of digging around on the web and came across this: http://home.clara.net/peterfrost/tryaneii.html . Isn't that just beautiful? I just love the curves and wood grain on that car, it's exactly what I have in mind for an eco velomobile finish. My cousin had an ol...
by Jeremy Harris
Nov 13 2007 2:53am
Forum: E-Bike General Discussion
Topic: Human/Electric hybrid velomobile?
Replies: 54
Views: 7684

MIK, This sounds like a good idea. If I've understood you correctly, then what your suggesting is a sort of shallow, boat hull like, structural floor pan, built up from thin ply, that carries all of the structural loads. The rest of the hull could then just be a very light fairing, perhaps removable...
by Jeremy Harris
Nov 13 2007 2:43am
Forum: E-Bike General Discussion
Topic: Full suspension VS no suspension
Replies: 28
Views: 3190

I agree with all the other comments, sometimes comfort, reliability and reduced maintenance/repair costs are more important than outright efficiency. However, the original question asked about efficiency. I interpret this as being "would an electric bike with suspension use more or less energy to tr...
by Jeremy Harris
Nov 12 2007 3:49pm
Forum: E-Bike General Discussion
Topic: Human/Electric hybrid velomobile?
Replies: 54
Views: 7684

MIK, My other hobby is aircraft design, see http://www.realityaircraft.com for one that I helped design years ago, or the attachment that is my current project (the one where I built the test section fuselage from strip plank balsa - no pics yet I'm afraid, I broke the test section.......). Curiousl...
by Jeremy Harris
Nov 12 2007 3:12am
Forum: E-Bike General Discussion
Topic: New bike project. maybe
Replies: 12
Views: 1402

Here's one trick that might work for hiding wires, it's used to turn round wing struts on experimental aircraft into streamline shaped ones. Get some extruded polystyrene insulation foam (the pink or blue stuff, not the white granular stuff). Cut out some slices that have a semicircle that is the ou...
by Jeremy Harris
Nov 12 2007 2:49am
Forum: E-Bike General Discussion
Topic: Human/Electric hybrid velomobile?
Replies: 54
Views: 7684

Rassy, I'm not sure, but think that the most probable reason that your pedal contribution makes such a difference on hills may well be down to the very high torque at low speed that your efforts can provide. Maybe the hub motors simply don't have enough torque when it comes to hauling slowly up the ...
by Jeremy Harris
Nov 11 2007 3:16pm
Forum: E-Bike General Discussion
Topic: Human/Electric hybrid velomobile?
Replies: 54
Views: 7684

I've been working through all the efficiency issues to try and see how they stack up in the real world. It'd be great to improve on the inherent efficiency of the motors, generators and batteries we have, but as I'd like something practical to build, I'm stuck with the sort of 80% figures quoted. Al...
by Jeremy Harris
Nov 11 2007 6:54am
Forum: E-Bike General Discussion
Topic: Human/Electric hybrid velomobile?
Replies: 54
Views: 7684

Thanks for the link, Miles. As I guessed, others have thought this through in a similar way! It looks promising, provided that the weight can be kept down. I've just done a stack of runs using the bike power calculator website and it does look like the concept would work well in a very light, stream...
by Jeremy Harris
Nov 11 2007 5:06am
Forum: E-Bike General Discussion
Topic: Human/Electric hybrid velomobile?
Replies: 54
Views: 7684

Human/Electric hybrid velomobile?

I've stuck a 405 hub on the front of my recumbent (which works well), but have now come to realise that my "pedal power" input is very much more variable than I thought it would be. Because a 'bent tends to freewheel down even slight hills pretty fast, there are plenty of occasions where I'm not ped...
by Jeremy Harris
Oct 26 2007 10:56am
Forum: E-Bike General Discussion
Topic: Newbie - How does this look?
Replies: 7
Views: 1092

Thanks for all the tips, I already have doubts about the SLAs, but they have the overwhelming advantage as a test pack of being free.............. :D I opted for a 405 and 35A controller after running loads of different options through the simulator at ebikes.ca What surprised me was that the low en...
by Jeremy Harris
Oct 25 2007 12:25pm
Forum: E-Bike General Discussion
Topic: Newbie - How does this look?
Replies: 7
Views: 1092

Newbie - How does this look?

Hi, my second post, and thanks very much to all who have posted here - I've learned a great deal over the past couple of weeks reading all the old posts. I'm hoping that my research is OK and that the direction I've now opted to go seems sound. I have a recumbent (a SWB TW Bent USS) that I would rea...
by Jeremy Harris
Oct 23 2007 4:39pm
Forum: E-Bike General Discussion
Topic: First-timer getting down to business
Replies: 64
Views: 7093

A first post from me - I've been prompted to join and post having read the excellent summary from lazarus2405. I've also been researching options for the past couple of weeks, in my case looking for something to take the sting out of riding my SWB recumbent on a couple of low gradient, but long haul...