Recumbent Conversion

[Rusty123]

Two weeks out from my first conversion (Bafang BBS01 350W/36V on a non suspended mountain bike) and I'm already thinking about my second. This must be a disease.

Anyway, I've got a Ryan Recumbent (LWB, USS) that I'd like to set up for long distance (as in 100 miles per day) self contained touring. I am a fairly competent pedaler, so the motor would primarily be for assist (mainly on hills), which will help with range. However, with a full load, plus motor and battery, this will be a heavy beast.

Question: which would be more efficient in this application, the BBS01 (350W/36V) or BBS02 (750W/48V)?

I'm told that a mid drive conversion provides better efficiency than a hub motor, due to the use of gearing. And I really like the Bafang conversion so far. But with this application, the mid drive seems to offer some special challenges, as follows: Since most kits replace the front crank, I lose the wide gearing that is so critical to recumbents (which tend to be slow on hills due to weight, but fast otherwise due to aerodynamics). Also, The configuration of controls on the Bafang doesn't lend itself to a recumbent with under seat steering, since the handlebars aren't visible to the rider (see photos in next post).

For these reasons, might a hub motor be a better solution? Perhaps one particularly selected for low speed torque, vice top speed? (Like the Bafang BPM or Grin eZee)?

 

[Rusty123]

Ryan Recumbent info:

[



http://ryanownersclub.com/vanguard/rcn29vanguardreview.htm

 

[crossbreak]

recumbents are heavy, but they have little drag. So you will go quite fast on the flats....50kph+ i guess...for this you will need around 350W. The bbs-01 should have its peak efficiency at around 200W, while the bbs02 will have it around 350W, so I would go for the bbs02.

A hubmotor with additional bbs01 for hill climbing would also be an efficient option, but you will have to interface 2 throttle inputs. not that easy, but possible with DIY electronics (arduino...). If you only do flats I would go for the hub alone. If you go on hills often, then the bbs02 (or a converted hubmotor with overdrive )

 

[crossbreak]

most recumbents have a small wheel, so they need a big chainwheel for reasonable speeds. You may want to thínk about an overdrive to speed up your drive chain like most converted hub users do, warren did this with a not converted hub (without making the axle spin).. he is more the efficiency guy than a hi-power/hot-rod guy so this is just perfect for his purpose http://endless-sphere.com/forums/viewtopic.php?f=28&t=23259&start=125#p540457

 

[Rusty123]

Some good ideas here. Wondering if a stoke monkey type arrangement will work - Warren's ride reminds me of that. (I have a 26 inch wheel in back, 20 inch in front).

I'm really just looking for hill climbing ability. I can make it go about as fast as I care to on the flats with pedal power alone.

 

[crossbreak]

stokemoney is about the same for hill assistance only I would go for the bbs01

 

[Rusty123]

stokemoney is about the same for hill assistance only I would go for the bbs01

I would be quite happy with the BBS01, except for the fact that I would give up my chain rings. No granny ring for climbing, and no large ring for speed. For sake of efficiency and range, I'm leery of giving these up, since I then would be dependent on the motor. For shorter trips or commuting, no big deal, but for long range loaded touring, I would like to be able to limit motor use when desired.

 

[crossbreak]

If you need only 2 now, you will need only one with additional 250W at hills

 

[samsavvas]

I would be quite happy with the BBS01, except for the fact that I would give up my chain rings. No granny ring for climbing, and no large ring for speed.

You could always use a BBSxx and just rebuild the rear end with a SRAM Dual Drive...

Savvas

 

[Rusty123]

I would be quite happy with the BBS01, except for the fact that I would give up my chain rings. No granny ring for climbing, and no large ring for speed.

You could always use a BBSxx and just rebuild the rear end with a SRAM Dual Drive...

Hmm -- I wasn't even aware such a thing existed. That would seem to resolve my concern. Any idea how stout it is (i.e. will it hold up to a crank drive)?

 

[Warren]

I have a standard 559 mm (26") rear wheel, like most recumbents, and most MTBs. I do not have an oversized chainring. I started with a 53 tooth, went to 52 teeth, but now run a 50 tooth. These are all standard road size rings. I only run one chainring, and a 12-34 cassette. I carry 1-5 pounds of water and about 5 pounds of tools and spares. This gear range is fine for all kinds of terrain on pavement.

My 50:34 gear has me doing 8-9 mph in low, and pulling ~450 watts on 17% grades. On these grades, on an unassisted bike, I am doing 4-5 mph. If I was touring, I would be carrying an additional 20-30 pounds of gear, and would definitely want lower gears for the added weight, and if/when the assist failed. I can get home unassisted with my current system in a pinch, but I'm hurting on steep climbs. Far from home, or a shop, I would want a granny gear for sure.

Either Bafang unit may work, if you run a SRAM Dual-Drive. I can't vouch for its dependability.

I ran the SRAM Dual-Drive set-up on Sheldon Brown's gear calculator, and the low range, with a 46 tooth chainring, and a 36 tooth biggest rear cog is still running over 5 mph at 80 rpm cadence...still a little high with a touring load, and a non-functioning e-assist.

My personal choice would be a classic Stokemonkey setup, and a 24:36 low gear, but you'd need to make sure it clears your remote steering linkage.

 

[Rusty123]

Thanks Warren. You've confirmed my suspicion that the BBS0X, with only a single chainring, is probably not the optimal solution for a long distance loaded touring recumbent.

 

[Rusty123]

I notice that it is possible to purchase a custom adapter that will allow the use of chainrings as small as 32 tooth on the BBS0X (here's one: https://endless-sphere.com/forums/viewtopic.php?f=31&t=56288).

According to Sheldon's calculator, a 34 tooth chainring, combined with a 11x34 cassette on the Sram Dual Drive, yields virtually the same gearing as with my current triple chainring (24/36/48).

The drawback of these custom (small) chainrings is that they move the chainline to the right in order to clear the BBS0X motor housing. In a conventional bicycle, this might be an problem, but with a recumbent, the chainline angle is reduced, since the chain is so long. Any guesses whether this setup would pose an issue? (I would probably stick with the 350W/36V BBS01, so that I could use the same battery on both bikes, so drivetrain stress would be substantially less than with the 750W BBS02).

 

[Rassy]

I have recently put a 48V 500W BBS02 on a bike for my sister, and the idea of hanging one on the front of my tadpole trike is intriguing, but I doubt I'll do it since I am pretty happy with the current mid-drive setup. I will enjoy following what you do with the recumbent.

About five years ago, before my brother suffered a stroke, we were planning a cross country ride. He and the other guy would go pedal only, but I was planning to use my LWB USS Vision with electric assist. I put a low speed (wound for a 26" wheel) geared Bafang in the 20" front wheel and another low speed bafang in the 16" wheel of a BOB trailer. Both were 48V and completely independent with a thumb throttle on the right side for the bike and a thumb throttle on the left side for the trailer.

Even though we never did any touring, the setup worked good, providing lots of space to carry the batteries and gear, and giving good redundancy, what with retaining the 27 speed pedal system along with the two independent assist systems.

One thing I currently miss with my mid-drive is the fact that since the pedal system and assist system are integrated, if anything goes wrong with the drive train you lose the ability to use either system. Plus, if anything goes wrong with the assist system the extra weight and lack of gearing options can make the trike difficult to pedal. Anyway, just my two cents, but if planning a long tour I think I would still favor a little hub motor over a crank drive.

 

[jkbrigman]

I used a hubmotor for my first ebike conversion, a SWB recumbent: http://endless-sphere.com/forums/viewtopic.php?f=6&t=35076

It performed beautifully and was superbly efficient. I chose a 9c 2810, which is a low speed hub motor. I fed it with 72 volts. The bike made 30mph easy, although it was a mega loser on uphills. Even though the base bike weighed 38 lbs and the loaded bike weighed 80lbs, it was a bullet. And I never did have a fairing. I even tried an experiment where I converted the pack to 22S and did a test run, hit 41mph no problem.

I "de-converted" the bike because it was very unstable and I was afraid if I hit a pothole and the front wheel collapsed, EMS would be getting me up off the pavement with a sponge.

Your bike would be very happy with a 2807-style hubmotor. There should be no need to drive it at 74 volts (18S LiPo). I'd drive it with a 12S (48v), a 12-FET controller and CA v3. With a fairing and 4P, you could probably make 100 miles with moderate pedaling at 20mph or better, average. (about 13Wh/mi X 100 = 1300 Wh)

I'm currently running an upright bike. It's big, beefy, heavy and sucks a lot of power. But for the job of commuting, it's been good so far.

However, I do have a LWB USS frame hanging on my wall waiting for a future conversion. I believe in e-recumbents, just not SWB versions.

JKB

 

[Warren]

Rusty123,

The chainline offset would be no problem at all. I would leave the front derailleur on, without the cable or shifter, and the stop screws set in to keep it in position. This will prevent the chain jumping off on bumps, etc.

I would suggest using a steel chainring, as it is small and you will be in it all the time, to reduce wear.

http://www.jensonusa.com/!MPGFK4Vt84ac7-5BWV19Ow!/Surly-Stainless-Steel-Chainring?utm_source=FRGL&utm_medium=organic&gclid=COjsrbeglbwCFWUOOgodnlwAMQ

I don't buy the hubmotor arguments. If your chain breaks, you are not going to ride very far, uphill, with a small hubmotor, on a loaded touring bike, with no pedal assist. I carry a small chainbreaker,

http://www.parktool.com/product/mini-chain-brute-chain-tool-ct-5

4" of chain, and two quick links for emergencies. As for weight and drag, with the Dual-Drive's gear range, the Bafang bb drive should be no different than a geared hubmotor in that regard. I suppose the motor freewheel could lock up, making unassisted pedaling like pedaling a direct drive hub motor. What are the chances of that?

 

[Warren]

I think the Bafang bb drive will be as reliable as any geared hubmotor in your application.

My one concern, if I was going to do a long tour on any e-assist, is failed hall sensors. The Bafang units haven't been around long enough to know if they are better than most hubmotors as far as hall quality. But assuming they are no better, I would not go on a long tour on any bike with a sensored controller. With sensible use, mine lasted 8000 miles, but they can fail much sooner.

 

[Rusty123]

I think the Bafang bb drive will be as reliable as any geared hubmotor in your application.

My one concern, if I was going to do a long tour on any e-assist, is failed hall sensors. The Bafang units haven't been around long enough to know if they are better than most hubmotors as far as hall quality. But assuming they are no better, I would not go on a long tour on any bike with a sensored controller. With sensible use, mine lasted 8000 miles, but they can fail much sooner.

Not much (none) experience with controllers here -- I assume with the Bafang BB, since the controller is integrated into the motor casing, that a controller failure is non-field repairable. Another good reason to maintain a wide gear range, independent of the motor.

 

[Geebee]

I was wondering if you coould just drill the chain ring that comes with the BBS01 and fit a second ring and either use the original deraileur or manual shift. I have a recumbent trike and as others have said chain alignment is a non issue.

 

[Rusty123]

I think it would take some custom machining (spider) to fit a dual chainring. Anything is possible though.

 

[Warren]

Rusty123,

Multiple chainrings won't work on the Bafang BB drive, or most other BB drives. The motor and/or gearbox are too wide to allow it. The stock chainring is offset to the inside, and is still further out than a normal big chainring. You may be able to put a smaller, second chainring to the inside of that one, but the chain wouldn't clear the motor.

http://endless-sphere.com/forums/download/file.php?id=128008

http://endless-sphere.com/forums/download/file.php?id=128394

How far do you plan to ride in a day on tour? Are you really ONLY going to use the assist on hills? These are questions you need to answer before you pick a system. If you only want a little assist on hills, and are fine with bicycle speeds up those hills, then you can run a small motor and battery. You aren't going to comfortably balance a long wheelbase recumbent at less than 4 mph, so you need approximately 16-17 gear inches...the equivalent of a geared hubmotor in a 16-17 inch wheel to use the smallest motor/battery/least energy.

http://www.recumbents.com/wisil/tetz/E-AssistMetric/default.htm

If you want to go faster up steep hills, you will need a bigger motor/battery/more energy. With the bigger motor/battery load, you will probably find you want to run the assist more often to deal with the extra weight/rolling resistance. It is a vicious circle. I designed my setup with the desire to average 20 mph for 100 miles, with constant pedaling. A bigger/heavier motor would not help. I would need a bigger battery. I might just get away with a "250 watt" motor, instead of my "350 watt" motor, but I'd run the risk of overheating it in hot weather.

 

[wineboyrider]

I was wondering if you coould just drill the chain ring that comes with the BBS01 and fit a second ring and either use the original deraileur or manual shift. I have a recumbent trike and as others have said chain alignment is a non issue.

Why not get a sram dual drive?
Seems to me that the type of riding you are doing is optimal for a bbs02 500w with a sram dual drive 9 or 10 speed cassette. Sure, a lot of gears are multiples, but eventually you will find the right one regardless of hill or terrain and the BBS02 should shut down if you are running too hot.

 

[Geebee]

Warren, I was thinking of putting a ring on the outside as with a 2+ meter chain line alignment is just not an issue.
If it is to bad I could always make a boom with an offset BB, one advatage of a trike

 

[Warren]

Geebee,

"I was thinking of putting a ring on the outside as with a 2+ meter chain line alignment is just not an issue."

It appears there is enough room between the crank arm and the chainring to add a smaller chainring outside, and it could be as small as 24 teeth.

http://endless-sphere.com/forums/download/file.php?id=120723

Of course, you would be shifting by hand. This would be fine for dead drive emergencies, or maybe climbing the Rockies. But I can't imagine using it on the Appalachian Mountains. You'd be stopping and hauling that chain up or down every five minutes.

 

[Warren]

wineboyrider,

"Why not get a sram dual drive?"
Seems to me that the type of riding you are doing is optimal for a bbs02 500w with a sram dual drive 9 or 10 speed cassette."

The SRAM Dual Drive is definitely a much cheaper solution than a Rohloff for use with this drive. I would not run a 9 or 10 speed cassette, however. You can buy just the hub and "clicker box". I'd run a regular SRAM 3 spd trigger shifter,

http://www.ebay.com/itm/like/380743212539?lpid=82

and a standard 8 speed shifter. An 8 speed cassette will fit this hub just fine, and the chain and cogs will be cheaper and more durable.