Long Distance High Efficiency

Well, it's time to hoist my idea up the flagpole, see who salutes and who throws tomatoes. Any attention is better than no attention, so here goes:

Mission:
35 mile-each-way commute to work. 25mph or faster, two significant hills each way, about 4% grade. Pedaling OK, but want to make sure I'm getting some "bite" at 25mph without having to spin.

Proposed Bike:
Road "performance hybrid": 700c wheels, no shocks, rim brakes. Aluminum frame, 700x35 tires. One 48-52T ring up front (no front derailleur), 36-11T in back.
Fenders, rear rack, flat bar. One shifter one side, throttle/buttons other side. Battery down low in the triangle. Stealth would be nice, but not sure if that's so important or not.

E-parts:
Crystalyte HS3540, 72V/40A controller, Cycle Analyst (ebikes.ca) 52v/11A LiFePo (cell_man).

Questions:
1) The bike I want to convert is an aluminum road bike with 700c wheels, rim brakes. I can't put 26in wheels on unless I do some kind of welding for tabs to accommodate disk brakes. I see nothing bigger than 26inch wheels for builds. Is a 700c wheel with rim brakes feasible at 25mph, or is it just not going to be rigid enough?

2) Is a road bike even a good idea? I keep seeing the same theme over and over: 26" wheels, hybrid, front or full suspension. Does ANYONE ride a converted road bike with 700c wheels, or is this just a no-go?

3) Assuming a 700c wheel IS feasible, isn't it more efficient?

4) I need the features of a geared motor, but I'm afraid for the distance and load I'll be putting on it, I simply have to do a direct drive hub motor, otherwise, I'll be chewing up gears and replacing them every year or so. Thoughts on that?

5) At what speed are shocks and beefier frame important? 25mph? 30mph? And of course, does battery size and weight also force the choice of a mountain bike?

Thanks all! Your feedback sought!

JKB

jkbrigman said:

52v/11A LiFePo (cell_man).

Click to expand...

Excellent battery from a proven supplier can't go wrong there however, i think it might be a tad on the small side for the distance your wanting to travel, hard for me as i don't pedal at all (unable to) so judging how much further one can go with pedal input is difficult, 35miles is a loooong way for a 52v 11ah Lifp04 though, i would have thought ~20ah worth would be better suited seeing you have a couple of hills?

RE: Motor...The MAC motor Cell_MaN does with latest version gears is oober reliable, my mate Matt.P (1000w on ES) has one and its been faultless with the new gears, i wouldn't discount geared frock to quickly. There's a handful of Aussies here using them as daily commuters with great success racking up some impressive miles before servicing is needed. Geared motor on 52v is going to cope better than a DD frock on 52v when it comes to hills at least. Usually upwards of ~60volts is needed for DD frocks before they begin to 'shine'

Best of luck with the build...

KiM

JKB, not too many do road bikes. They are usaly to flimsy. The small tires have no cushion to do 30mph if you hit any potholes or what ever.

i have a BMC V1 on my wifes Rielegh 700 hybrid with rim brakes. Top speed is 22 on 36v. Wife would rather to ride POS wally world NEXT with 26" tires and crap suspension that that.

There has been a lot of members here asking the same thing about road bike conversion, but I think the reason not to was small dropouts and a weak frame. Most were asking mainly as a samll motor assist not a full blow commuter, like you are planning.

I'm sure others will be throwing tomatoes soon.

Dan

I am of the opinion that for the ultimate efficiency (including good hill-climbing), you will need to give the motor some gears. My research leads me to a cell_man geared hub that is driving the bottom bracket (BB). Also, higher voltages reduce the amps needed at any given moment so I'd start my plan with 48V at a minimum.

If you agree, then, this will limit your frame choices. Plus it may require some custom brackets to be fabricated from scratch.

20 amp hour 36v battery on a 8T MAC motor, pedaling the entire time, will do this.

You will have ran your battery down to completely dead however.

DD motors are less efficient on hills, but more efficient on flats when they can maintain their maximum efficient speed. You may need more along the lines of a 25AH battery to do the trick.

There is nothing more or less efficient about a certain type of wheel, it's all on the tires and 700c wheels usually are intended for narrow tires with low rolling resistance.

You will definitely want at least a front disc brake with all that additional weight and speed.

( this is why most of us are using mountain bikes. )

My first ebike was pretty much what you are thinking about. It wasn't exactly a road bike but rather a touring bike which came stock with drop handlebars, 700Cx28 tires and cantilever brakes. I converted it to flat bars, 700Cx35 tires and though I primarily ran a small Bafang front motor for a while I did have a front (9x7) 9C motor installed. The bike on 48V was capable of close to 30 mph.



So yeah given the right frame you can build what you want though a touring or hybrid frame would be better choices than a pure road frame unless that's what you have already. A touring or hybrid frame will more likely have a steel front fork (if you want a front motor), a 135mm rear spacing compared to a road bike 130mm (for a rear motor) plus they will have eyelets for racks and fenders.

Some things to keep in mind;

One important thing for a 30mph capable bike is brakes and the original canti's on the Raleigh above were definitely not up to it. I did eventually swap them for a good set of V-brakes which performed far better.

The battery you spec will never get you 35 miles at 25 mph, for that you'll need 48V/20AH.

You don't need a 40A controller for 30 mph and 4% grades, a 20-25A would be just fine and won't subject the dropouts to as much torque.

Finally, if you're building an ebike mainly as a means of transportion where pedaling efficiency is not much of a concern then there's little reason to choose a road bike frame as a basis, which is one of the reasons why most folks don't use them.

-R

PS, I decommissioned the bike above permanently becasue it simply was too harsh on bad roads and bike paths. I still place a premium on pedaling however so my third ebike build is just a refinement of the original concept as it re-uses a number of the parts from the first one but with a nod toward a bit more comfort with the front shock;

You don't want a 15lb motor on a 20lb lightweight road bike. There's really no good reason to want a road bike unless you are running very low power <400watts and have a very light motor and battery. You can ride 26x1.5" tires at 80psi if you get the good ones. They will handle rough roads tremendously better than a 700x25c road tire, especially with a heavy hub motor. Even good roads aren't perfect and you will want some meat on your tires. Every imperfection will send that 10 or 15lb hub motor straight into your seat on a hardtail - not good after a while. Even on 26x2" tires. Look into full suspension unless you really do have perfect roads.

You will need at least an 900watt hour battery, minimum. 6 turn Mac hub on 36v 25ah would do it if you assist on the hills and get aero. 35 miles if your distance then charge, right? Don't cut it too close, some days will have nasty wind and eat more power.

If you want efficiency, build your bike to go 30mph (sounds like the top speed you want) and NO MORE. Running higher voltage that is capable of 35 or 40mph will cut into your efficiency of what you could be getting while at 25-30mph. Your goal is to be full throttle at the motors most efficient speed at your target speed. 6 turn Mac on 36v will go 32mph. 48v on an 8 turn Mac may be a better choice since you can get a 48v 20ah battery easily. Don't skimp on battery size.

The CA will be great in that you can limit your amps to fine tune the balance of performance/efficiency that you want. Lower amps will boost efficiency a lot.

Listen to veloman, he knows.

I only have 1 stickler point with what you said. The slower you go, the better the efficiency, especially above around 15-20mph.

I rode the tiny 250w geared motor for a month or two, and could get up to 14 miles on 5ah doing 18mph solid. Now on the same battery with the MAC motor, i'll do 10 miles on that same 5AH doing 26mph solid.

That's a big difference in efficiency.

Thus i say, stick to the initial 25mph ldea if possible. It means you will need a few less amp hours to do the same job.

Pretty much agree with most of the tomatoes. You are talking about 70 miles a day right? For one thing, road bikers that do that kind of daily mileage do have to do a lot of bike maintenance. In particular, if the road is rough wheel tuning can be needed quite frequently. Thin tires cut easy on road trash. Plus you have the usual stuff, pounded ass, hands going numb, etc.

For those reasons, most who end up with a nice full suspension E bike are not going back to a no suspension frame. An ebike generally has a 15 pound motor wheel(motor tire tube) and a 10-20 pound battery. When you ride a bike, you can stand the pedals and let the wheels rocker back and forth with a suspension like rocker action. Strap 15 pounds of hubmotor to one wheel, plus battery somewhere on the bike, and now the heavy wheel gets a real pounding. So for me, truing wheels went from weekly to twice a year when I switched to FS bikes.

The battery is going to have to be big to do 35 miles at 30 mph. This isn't the first thread like this. At 15 mph, you could do it on 36v 20 ah or 48v 15 ah. That would be a harsh on the battery, twice daily 100% discharge too. A bit of wind, and now you run out of power, say, 10 miles from home? I think to do this commute at 30 mph, you'd be looking at 48v 30 ah, to reliably make it in all weather conditions. So,,,, 25-35 pounds of battery?

Is it just me, or is this seeming like quite a load for road bike wheels and no suspension?

Here is the part where I point out what a much better tool for the commute a small motorcycle or scooter would be. Something in the 125cc minimum ballpark. If you don't have wide open road with no stop signs, a 25 mph average speed means at least 3 hours a day on that bike, 4 if you have lots of stops on part of the commute. Not saying don't try to do it on an ebike, just that a motorcycle is much more practical for 70 miles roundtrip. 30 miles roundtrip is my commute, and it works just fine. 40 is still doable, but beyond that takes up a shitload of time on a bike.

But you want to bike, so what do you do? One method is to compromise. At one point I was using motors that melted if I tried to climb the large hill up to my house. The hill was six miles from home, so I drove to the valley floor, and then biked 9 miles to work. You'd solve a lot of problems if you found a place about 15-20 miles from work where a car can be left for the day. Then ride a distance that is not so hard to do at 25- 30 mph. Cut the mileage in half and then the road bike option doesn't seem so dumb after all with a 10-15 pound battery aboard.

On the subject of efficency, just some numbers for you. Only the really incredibly fit cyclists can put out much more than 100w for more than an hour. You might do better, but 30 mph takes about 600-800w of power, including the losses in the system. While your 100-200w might not lose so much of it to heat like a motor does, you still don't really contribute that much to an ebike going 30 mph. At best, I can sustain adding 2 mph to my speed for a short while, and 1 mph to my speed for the long haul, if I'm traveling above 25 mph. However, since 15 mph may only take 250 watts, you see how an ebike ridden much slower can get hugely more efficient, especially if you put out your 100 watts or so.

Somewere in the middle is where lots of commuters travel. 20 mph is way more efficeint than 25 or 30 mph. And even just slowing to 18 mph is suprisingly more efficient than 20.

Lastly, since it's all about the wind resistance, a recumbent bike can be the most efficeint way to go. So if you really want to get the 70 miles a day done, a recumbent bike might be the way to go. Comfy seat helps with the bikers ass, and less drag means you carry a smaller battery to go a reasonable long commute speed, say 25 mph instead of 30. The bike can be capable of 30, but for me, I get better efficiency if I can't go that fast.

Dogman has it right. Get a dual 26" wheel recumbent. The longer the wheelbase, the less need for suspension, if you keep the motor and battery weight in the center of the wheelbase.

Real life example. I am 64 years old, 165 pounds, not particularly fit. These days, I can ride a roadbike at 16+ mph for an hour max. I can ride at 12 mph all day.

Speed kills...efficiency.

On my bottom bracket drive, 61" wheelbase recumbent, I ride 60 miles at 21.5 mph, 11 Wh/mile. I can ride the same route at 18 mph and 7 Wh/mile.

My MAC is a 350 watt on 12 cells. If I had cell_man's "1000 watt" motor on 24 cells, I could pull about the same amps, losing about the same percentage to motor heat. In theory, I could average about 28 mph on about 22 Wh/mi. I would need to almost run out my 1.1 kWh pack, 70% DoD, to do your 35 miles. And since it would be a 24 cell, 15 amp hour pack, instead of a 12 cell, 30 amp hour pack, the doubled C rate would probably waste the last 10% of charge heating up the pack!

And at 28 mph, I would want wider tires, which would eat up even more watt hours.

I'm setting up my first ebike for a similar purpose. Thought i'd share my rather different looking ebike plan as some food for thought.
My planned Journey:
Only just over half the distance at 25km(15.5mile) ride each way with 1 200mtr steep climb.
I have the option to sometimes get a lift half way with my wife depending on schedule or take the bike on a train for a part commute.

Other Critera:
Time is important and I need to be in the 30mph+ ballpark for a stretch of highway that will soak up too much time compared to scooters and car if done slower (yeah, efficiency, I know. Tell it to my kids if I don't get to feed them dinner or see them in the morning because of efficiency)
I'm in Wellington NZ so one way or another this bike will experience heavy wind and hills.
Must look like a bike, not a frankenwiring mess or crazy motorbike thing. I don't want attention or funny looks on the train or road.
Some offroad fun can be had through some sections of my commute and on the weekend.

At 36 I'm way out of shape so I'm keen to peddle to get my fitness up but am realistic about my output relative to the blue box and black disc
I've done many thousands of kms touring on bikes when younger and am keenly aware of comfort and maintenance issues when clocking a lot of miles. Full susp, big, tough tyres and the right seat are the way for me.


My planned Setup with much help from Kiwi (member here and local e-bike expert):

Specialized Enduro Comp 07 Full Susp freeride bike. really strong. Big travel on the front shocks but still pedals well.
Hookworm Urban assault balloon tyres (I see roadies patching tyres almost every day on my commute. I ain't doing that)
9C 2808 rear hub motor - wound for the hills and to hit my required speed with some wind headroom at...
72v via 2 x 36v 10ah Ping LifePo Batteries Likely mounted on a..
Seatpost rack with custom brace for added strength. (may try other config's later)
Custom Rear 8mm Torque Arm courtesy of Kiwi.
50a programmable Speed control.
throttle speed control.
3 speed cruise control
Regen Switch (hopefully setup to be controlled via throttle with the programmable SpeedController)
cycle analyst
1600 lumen magic shine led light

My kids will also not be appreciative of me failing to make it home in time because I am dead so:

AGV Blade scooter helmet - I just don't think a mtb helmet is going to be enough at 30mph in traffic. Looked at snowboard helmets but I think the visor will be a real plus if the weather turns pear shaped and it doesn't look too bulky for a bike. Just wish it had a twin shield like the rjays tss tomcat but I can't imagine wearing that one on an ebike.
666 core saver - might be too hot but got one very cheap so i'll see how it goes.
bright yellow/green jacket and back pack cover.

I'd be interested to hear how you get on

BIG FAT EDIT. Ignore half what I say for the next page or two about emergence. I thought he was saying a hill 1200 meters tall. He's talking about 1 hill, 200 meters tall. Duhhh.

Recipe for disaster emergence. Your idea of what your performance will be up a steep hill ( at least 10%?) is in la la land.

10 amps continuous from your pings won't provide near the wattage you will need, and if you pull 20 amps continous you are too likely to stress the one weak cell in the assembly, and kill a cell group. Under full load up a hill, a 50 amp controller could easly be drawing your ping at 3-5c! That won't fly, and using less you won't be flying up that hill either. You'll be going a lot slower.

At the very least, you will need a much more capable battery. 72v 15 ah A123 might do it, or lipos for a frankenbattery. It might even take more ah. Just depends on what your continuous wattage actually is. Bottom line, you will need a big battery and at the very least need big panniers. A cargo bike might even be the best way to go.

I also think an 8x8 (2808) winding is still too tall for that kind of climb, unless it's not steep. For me steep begins at 8%. Below 8% your winding would work fine, and even a 2807 would be hunky dory for 5-6%. The deal is not so much can it climb it, but will it climb it efficiently enough.

I think your best approximation of what you want is going to be a 2810 winding, and feed it about 30 amps of 72v. You'll have at least 30 mph on the flat.

You won't get 30 mph up a grade, say 8%, on a 9c motor for 15 miles continuous without melting it. Period. But 20 mph up that grade with the right winding is quite possible. Unfortunately, because I have a chonic illness, I never did a real world test of a 2810 on a ten mile 8-10% grade road nearby. So I only have real world data on 8% for about 2 miles. The 2012 definitely reached an equilibrium temp and wasn't going to overheat, and the 2810 looks like it would do the same thing, if fed about 20 amps of 72v. (likely to be 1500w measured at the CA)

Just what is the grade you will be dealing with? Sounds to me like a pretty steep one, comparable to pikes peak. You should see the pikes peak threads, that discuss a race up 25 miles of steep grade. The key is can you sustain that output without overheating.

emergence,

If you don't have hills, or stop/start acceleration on your commute (yeah, right!) the solution is easy. A human powered velomobile is great in Holland, where it is dead flat, and bikes have their own roads. In most of the uncivilized world we need to fight for our lives with two ton, engines-of-death. The bike you want/need is much closer to this:

http://www.zeromotorcycles.com/zero-xu/specs.php

And remember, if your 30 mph stretch is uphill, that 65 mph top speed...becomes 25 mph up an 8% grade!

Oops! I plugged the wrong numbers in the calculator. Make that 54 mph up that grade.

jkbrigman: I have put together two ebikes that are quite different. One is a 700c but it is a hybrid with an Xtracycle conversion with a Stokemonkey so it is quite different that yours and does not use a hub motor. The other is a 26 in front fork shock "mountain bike" with a 2610 (I think that is the correct designation) 9c. I agree with several posters that going that distance is going to require some serious (heavy) batteries. However, if your 700c tires are 38's and not road tires, I think they can handle it. I carry a 15 Ahr 36 V LiFePO4 on the 700c and can easily do 20 miles and that includes a lot of hills (edit: by "easily" I mean keeping well out of the end-of-charge range. I have been 30 before but was hitting the LVC at the end). Of course, on that bike, it does not have a hub motor (it drives through the cranks) so the motor efficiency on hills is no different than on the flats.

However, for the grades you are looking at, a hub motor will be more than fine. I would suggest mounting a pretty big tire, like a hybrid, to give you and your frame some cushion. I think a 38 would be plenty. If all you are carrying is the batteries and yourself, I think the frame will probably hold up as long as you aren't beating it through potholes. I have fallen in love with LiPO because of the high C rate, but since you will have plenty of Ahrs, the C rate is not as critical. On the 26" mountain bike, I have just 5 Ahr of 72 volt LiPO. The motor is only a 10 turn 9c but on 72 volts, it does pretty well; top speed is around 28 mph. Others have indicated they can go a bit faster. On a 700c wheel, you will be going around 10% faster I think (depends on tires). In fact, I really really enjoy flying around on the hub motor bike; the Xtracycle is a "minivan" while the 26" bike is a sports car, so to speak. The mountain bike can easily do a 14 mile round trip will significant hills and not holding back on the throttle with the 72V 5 Ahr. Probably will do more because I only went to about 50% DOD, if my CA is correct. I THINK it could do 20, which is getting close to half your range. And the battery pack is so small it is hard to believe it will go that far. And frankly, I barely pedal. A token effort at best.

In short, with larger tires, I think your road bike would work. For comfort, if it was me, I think I'd get a hybrid front suspension cheap off craigslist and start with that though. 35 miles one way is a long way but I don't see any reason why you can't do it with the bike you have. Would definitely get different tires.

Re: emergence -

72v 10ah ping......... forget it if you have hills. Why not get A123 from cellman? If you can charge at work, you should have no problem getting 16 miles from two 36v 11ah batteries at 30mph. Then you can pull 3-5c on the hills.

Sorry, I didn't mean that I expect 30 mph on the steep climb, that's motorbike territory. 15-20mph would be ok for the climbing, just needs to be enough not to let the motor bog down and overheat. At the end of the climb it is the end of my journey home so its only one way and I can also go all out.

This is the gear i can easily source locally.

Exactly, the main flaw in the post was the ping. An 8x8 should climb 5-6% grade just dandy at 72v. Just a problem if you grade is steeper. Still will take a big pack to blow watts like that for 15 miles. That's part of the pikes peak problem.

By comparison, my commute is 15 miles uphill home, in hot desert heat all summer. But the total climb is only about 1000 feet up. 1/3 of yours. I can do 30 mph all the way to work, downhill, easy. But coming back up to home takes about 20 min longer. For you, the uphill part is so much longer, it will be a lot slower on the uphill leg. To climb the hill at 1500 watts with a 72v 20 amp controller should work, and take a lot less battery than doing it at 3000-4000w. At that wattage, 8 mile rides are more in the "not melting my motor" zone.

The plan might work fine with a huge motor, but it would be asking a lot of any winding of the 9c to go 30 mph up even 5% grade.

If you really want efficiency at 25mph and comfort is anywhere on your list (it better be high for 70mi/day), then nothing is going to beat a recumbent. Their tremendous wind cutting advantage is why they're outlawed for bicycle racing. Even a comfort cruiser feet forward semi-recumbent is going to beat the road bike with a little attention to aero, like a tailbox for your stuff.

My commute is 13 miles one way but with a lot more climbing than yours - 1250 ft elevation change, some of it more than once. I have a 9C 6810 and 72V 10AH Lipo on an aluminum hardtail MTB. It takes 65% of the charge to get there, and about 50% to get back, so of course I charge at both ends. I would expect my extra climbing is about the same as your extra distance, so a 72V 10AH pack might do it. I plan to go to 72V 15AH to have a bit more range and the option to not charge as often.

Most of the climbing is not too steep so similar to yours. One grade is about 10%, the 6810 goes up that at 16 mph if I pedal hard. It is only a quarter mile or so at that gradient so the motor warms up a bit but no problem.

The top speed of my setup is just shy of 30 mph and my goal was to climb pretty well at 20 and it does that. Grades less than 10% it flies up. Even on 10% I can almost keep up with gas scooters, at least some of them. I suspect I can beat a moped on that grade but haven't seen any of those lately. It definitely outperforms my old moped of college days.

Traveling at much over 20 mph on a bike is pretty rough on our roads. I have a front suspension and a thudbuster seatpost and use Big Apple tires to help soak up the road. If I was planning to travel at moped speeds (over 25) I would go for a dual suspension bike with fat tires. Think moped imitation.

My build thread is linked in my signature if you want more info on that.

Get a stokemonkey or another mid-drive. I have a similar situation - long distance, and more hills, steeper. If I tune the cycle analyst so that I have 20MPH max and 350 watts max, I can go 40 miles round trip on a 15AH 36V LiFePo4. Rolling hills all the way. Climb any hill in town, some of them wicked steep. If I get bored, and set the Cycle Analyst to 30MPH (bike peaks out at about 26mph on the flats) and 750W, I have half the range, but I can charge at work so that is no big deal.

When I have compared the efficiency I get with a mid-drive to some of the posted efficiency numbers here, I am getting maybe 30% more miles on a watt by driving the chain. THis goes dowble in hilly teritory, where the hub motor stars sucking amps hard, but the mid-drive is still spinning at 90 RPM like it is supposed to.

Hard tail? If I hit a bump at over 20MPH, I really feel it. Sometimes stuff flies out of the saddlebags. Biggest mistake I made was making this bike hardtail. Next e-bike will have suspension front and rear.

--Lawrence

Wholly Krappe! You guys are all awesome. THANK YOU THANK YOU THANK YOU. It's as if everyone "gets it" - the mission of the entire forum, no junk-talkin, self-aggrandizin crapola.
Everyone's comments are based on experience, and that's exactly what I wanted....I'll follow this message with my response but first, just a plain, flat out thank you!

I can't reply to everyone individually via the thread (it would become huge and much less nutritional) but I have read EVERYONE'S comments and I thank you, and ask you to please keep speaking up. Any real-world experience is more than I have right now!

Thanks!
JKB

John in CR said:

If you really want efficiency at 25mph and comfort is anywhere on your list (it better be high for 70mi/day), then nothing is going to beat a recumbent. Their tremendous wind cutting advantage is why they're outlawed for bicycle racing. Even a comfort cruiser feet forward semi-recumbent is going to beat the road bike with a little attention to aero, like a tailbox for your stuff.

Click to expand...

Seriously, I think if you don't have a lot of crazy city traffic to deal with, a recumbent is the way to go. An upright is just fighting the wind, and it doesn't win. 70 miles a day is a ton, and I myself would enjoy that a lot more on a recumbent with rear suspension. Then you can also add a front fairing easily, with your tailbox and REALLY cruise without sucking the watts too bad.

Now that it's colder out, I'm wearing jeans and a jacket and I really notice how much it slows me down. I don't see 30mph all that often now. Even my normal backpack adds more drag, compared to my Dueter Race.

I really want two things:
1) Live in an area where I can ride a recumbent safely (bike highways)
2) A sweet mid/low racer

I can only imagine how fast a good e-recumbent would be. I bet it would feel like sitting a rocket-sled

I like what pdf said about the tires - it came stock with 700x35's and they do a great job. Roads here are pretty nice - only one stretch bumpy that's under construction. I want to get back to that bike sometime, but for now, I'll set that subject aside and move on to something else:

You guys with the recumbents reminded me of something, so I ran out to the garage and FOUND my recumbent under some boxes I've not moved for two years:



It's an Actionbent 26" rear/20" front above-steering SWB recumbent! (that's not me on the bike - it's one of the guys from the former Actionbents.com, a pic I found cached on Google)

I'm with you 100% that this bike would cut the wind resistance dramatically, and it just so happens, that's a big concern on this ride route - the ride route outbound is largely southwest-facing, and our prevailing wind is from the west-southwest. So a recumbent would definitely help with that! What's so SWEET about using this bike is that the rear wheel is 26" (front is 20") so I could just order a stock, standard hub motor/wheel combo and use the cool Maxxis Hookworms or Kendas or whatever. I wouldn't even have to change the gearing - there's an 11-34T cluster on the back and what looks like a 52 on the front!

There's a very important point I realized about using this bike: I would not have to change out the wheels or sprockets - they are already OK for 20mph or so . Heck, the Kenda tires on it are fat enough that I might even be able to use what's installed if I add a puncture strip and innertube goop. For the other bike, there was all the stuff I'd need to do. With this one, I think I could add just the motor/controller/battery system and have something I could start experimenting with.

So, let's talk about this. Looking more at this bike as a possible conversion target, here's the questions I've got:

1) It's an insanely heavy bike for it's size - I think it's 42lbs or more. Is that no big deal, especially compared to wind resistance?

2) I guess I would have almost all choices of drive system for this bike?: stokemonkey, chain assist or hub motor (either direct or geared). The recumbent ebike riders have already praised the chain drive systems. Can I get some more feedback on this? IF power transmission via the chain (or a parallel chain drive on the other side of the wheel) is going to be much more efficient (one said 30%), can I get more feedback on battery sizes and range vs speed? (what battery do you guess it would take for 30 miles @ 30 mph?) What about regen - can systems that drive the chain do regen, or is that undesirable?

3) The bike has NO SUSPENSION and RIM BRAKES. Is that a show stopper, or does it matter if I plan for, say, 25mph max and cruise around 20mph?

4) Can you get a great tire like the Maxxis Hookworm for a 20" wheel?

5) The reason I've not touched this bike in two years, is that in 35 years of riding bikes, it's the only bike I've ever fallen over on. (seriously) I don't think of this bike as being very stable in turns. Now - is it just me, and I need to get used to it and quit being a whiny crybaby?

6) Since I do think it's unstable as-is, is there a way to get the motor and batteries mounted down low on the bike?

7) A tailbox was previously mentioned - I'm all for that, or even adding a front/full fairing system. Any suggestions or pointers on adding a fairing or tailbox?

Thank you Recumbent Dudes! You've made me one Stoked Monkey!

JKB

The recumbent version of ES: http://www.bentrideronline.com/messageboard/index.php


I think you need to just practice riding it more. The first time I tried a recumbent I was super sketchy on it, very unstable. Then I went to Easy Street Recumbents here in Austin TX and the owner gradually showed me how to ride in his parking lot, starting on the easy uprights. I don't think a recumbent will ever rival an upright for super technical riding like off road singletrack, but it should be enough for most roads.

You may not need suspension on a recumbent, if your roads are 'good', even at 30mph. Rim brakes.... you can do it, it's just not as safe. I ride 30mph now on v-brakes, and I've never needed more stopping power.

Weight shouldn't matter if your route is steady and the climb isn't too steep. Think of how efficient a car can be over rolling hills if it doesn't need to touch the brakes. Due to the great aerodynamics, there is much more equilibrium in regaining what speed you lost on the uphill. That's what the motor is for. Now, if you were stopping every half mile or going into hills from a low speed, then it's an issue. (though still not as big as aerodynamics).

You can't realistically have regen on a mid-drive. You don't need or want it if you are riding steady over fast roads. You will want to have no drag when you can coast down the low grades at 30mph.

I'm pretty sure there are 20" Hookworms.

Look over that forum listed above for all about fairings/tailboxes. There's even a homebuilders section.

jkbrigman said:

Wholly Krappe! You guys are all awesome. THANK YOU THANK YOU THANK YOU. It's as if everyone "gets it" - the mission of the entire forum, no junk-talkin, self-aggrandizin crapola.
Everyone's comments are based on experience, and that's exactly what I wanted....I'll follow this message with my response but first, just a plain, flat out thank you!

I can't reply to everyone individually via the thread (it would become huge and much less nutritional) but I have read EVERYONE'S comments and I thank you, and ask you to please keep speaking up. Any real-world experience is more than I have right now!

Thanks!
JKB

Click to expand...

I would take cognisance of the fact that the efficiency figures of the 72 volt battery set ups can be distorting when comparing ranges and saying such and such amps gives x kilometre/mile range. They are completely different. You are better off calculating the total watt hours of a battery pack and measuring efficiency in watt hours per kilometre/mile. For example, a 48 volt (52.8 volts nominal) 11.5 amp A123 battery gives you a total of 607 watt hours.

A 72 volt 5 amp/hour battery is 360 watt hours, a 48 volt 5 amp/hour is 240 watt hours and a 36 volt 5 amp hour is only 180 watt hours. Strictly speaking each voltage would have a bit more than that for each category as the nominal voltage is higher depending on the battery chemistry etc. However, that is just a marginal increase.

You would be better off knowing how many watt hours per kilometre/mile and get a number for efficiency. My own set up a 500 watt MAC 8 turn, 16 series 5 parallel A123 battery gave an efficiency of 21 watt hours/kilometre during a short test run (three kilometres) at full throttle hitting over 50 kph in some places. Bear in mind that I have a Veltop canopy which increases the weight of the bike further and creates more drag at such speeds.

Therefore, my 607 watt hour battery would give me a range of 28 kilometres if the short test run is anything to go by. Probably less with more hills and a headwind.