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Blade-Runner 06-19-14 10:35 AM

Electric Hub On Tandem
 
I've been thinking about buying an electric hub motor for our tandem. One of the systems I'm looking at is the BionX S350 DX. The reason why is to help us with the longer climbs out here in Las Vegas and to help keep us keep up with riders on single bikes. My wife is more of a recreational rider and I'm a CAT 1 XC and CAT 4 road rider. I'm thinking the added power would make riding the tandem more enjoyable for both of us.

Has anyone else installed an electric hub motor on thier tandem(s)? Any recommendations and your thoughts would be helpful.

Team Fab 06-19-14 01:47 PM

One thought would be to compare the price of the hub installed the price of some light weight parts for the tandem. Rather than add 20 pounds to the tandem take off some weight. Wheels may be a great place to start.

fietsbob 06-19-14 01:59 PM

Hub motors are weak on hill climbing torque, but OK on Flat land speed boosts ..

only by gearing the whole motor output thrugh the whole drivetrain * can you get the motor spinning enough

then it's the gearing that creates the Torque to move a mass up a slope.

Stoke monkey (pat) uses a cross over drive .. were you to hire a Machine shop to create a way to fit it between the seat posts .. that may be possible ..

The company uses An Extracycles extended rear space to fit the Motor where the rear wheel would go on most Bikes . $3K + ?

merlinextraligh 06-19-14 02:00 PM

Quote:

Originally Posted by Blade-Runner (Post 16864850)
My wife is more of a recreational rider and I'm a CAT 1 XC and CAT 4 road rider. I'm thinking the added power would make riding the tandem more enjoyable for both of us.

Dude, you should be able to climb, even if she isn't pedaling, just a bit slower. Just think of it as a better workout.

Blade-Runner 06-19-14 02:26 PM

Problem is climbing times on the tandem are around 50% slower vs my times on my road bike which sucks the life out of me.

attached is a profile map of one of our favorite places to ride, 34 mile loop.

http://rivermountainstrail.org/site/...on-profile.jpg

Team Fab 06-19-14 02:27 PM

If you are riding with singles it is always hard to keep up on the climbs. You can try to time a move to the front of the pack with the start of the climb. The pack will then slowly pass you during the climb and hopefully you can tuck in at the end of the pack at the top of the climb.

Blade-Runner 06-19-14 02:29 PM

Our climbing miles are long, up to 10 miles or so long.

fietsbob 06-19-14 02:30 PM

Get a motorcycle , fit a stayer roller behind it & you can tow everyone over the mountain. motor pacing ..

Bad1 06-19-14 02:50 PM

Quote:

Originally Posted by Blade-Runner (Post 16865566)
Problem is climbing times on the tandem are around 50% slower vs my times on my road bike which sucks the life out of me.

attached is a profile map of one of our favorite places to ride, 34 mile loop.

http://rivermountainstrail.org/site/...on-profile.jpg

looks to me like about 10 miles and a 700 foot vertical climb, that's pretty gentle climb. Did 117 mile Fondo 2 weeks ago, at 40 miles in the hill climb race kicked in 4 miles 1000 vertical, 7000 for the whole ride. Rule # 5 Velominati ? The Rules

Blade-Runner 06-19-14 05:19 PM

Quote:

Originally Posted by fietsbob (Post 16865582)
Get a motorcycle , fit a stayer roller behind it & you can tow everyone over the mountain. motor pacing ..

Total worthless post, adds nothing to the topic.

fietsbob 06-19-14 05:25 PM

Motor pacing is part of training to go faster .. you should know that..


You didn't get the message about hub motors wont lift you over a mountain like you wish :roflmao:



good for battling headwinds over flat country though..

vrooom3440 06-19-14 07:29 PM

Wow talk about an unsympathetic crowd :(

One path to improvement would be to give the stoker more seat time to develop. You did not tell us how long she has been riding? I have found a gradual improvement there just from seat time for my stoker. Since she was starting from ground zero it has been a noteable improvement.

I am having issues with the descriptions given above. Any electric motor will generate some amount of torque. This is what makes things go and whatever the motor generates is torque you do not have to generate or torque added to what you DO generate. This will be a boost on the flat or going up a hill either way. What you will need to pay close attention to is the torque rating of the electric motor. I suspect most are familiar with pretty low power motors, and you will notice the most difference in speed on flat ground where you are merely overcoming aero drag.

A tandem is a much bigger load and you will have to do some careful analysis and engineering to make sure you get the right good parts. And they will probably be pricey.

Electric stuff has come a long way. I have read of someone building an electric recumbent tadpole trike that could literally smoke the rear tire. And a couple days ago I test rode an electric motorcycle with over 100 ft-lbs of torque and a 0-60 MPH time of 3.3 seconds. Now THAT was a fun ride :D

JanMM 06-19-14 08:07 PM

Maybe someone in the Electric Bikes subforum will have some insight and info related to tandems. There is seldom any mention of electric assist in this forum.

Bad1 06-19-14 08:34 PM

If you really think you would like some electrical help check this out for a tandem specific electrical bike.
https://mobile.twitter.com/EBikePete...26816794394624

chojn1 06-19-14 08:46 PM

Our very first tandem was a $150 ebay clunker that I heavily modified in order for it to run at all. After upgrading to our second tandem, I played around with that original frame adding an electric hub I bought from some guy from California also via ebay. I modified that system to work with a 48v lithium battery I had lying around.

That contraption was heavy at ~60lb but it was fast. It can do 30 mph without any rider input. The gearing will not allow it to go any faster. We will just spin if we try to pedal past this speed. Riding that thing was just like riding a moped. After a few months we got bored with it and went back to our human powered tandem.

Yes, the motor will help you up that hill. But, it is so much more gratifying if you did it with your team's own power. As your stoker get stronger, you'll find that you will not need or want that motor. It'll just become extra weight you don't want to lug around.

If you still want to try, let me know what info you need.
Have fun experimenting,
CJ

Carbonfiberboy 06-19-14 10:59 PM

Stoker power is the way to go. I almost never ride my single anymore. Why would I train myself and not her? If I go out, Stoker goes out. Stoker loves it and has become much stronger. True, we still climb about 50% slower than I would on my single, but so what? We have fun. As far as singles go, we ride a little differently than I would on a single. We get aero and drop them on the descents, vanish on the flats, and then sometimes they catch us on the climbs and sometimes we wait for them at the top. If there's no big climb coming, we just ride with the group normally. For major pass climbs, we leave a little early. On small rollers, we accelerate from the back, pass everyone, and go like the devil on the bump. When we go past the lead rider with a 10 mph speed differential, no way will they grab on. It's a little weird, but they'll get used to it. Use the Force and deny them the Vortex.

Team Fab 06-20-14 08:24 AM

Quote:

Originally Posted by Carbonfiberboy (Post 16866724)
Stoker power is the way to go. I almost never ride my single anymore. Why would I train myself and not her? If I go out, Stoker goes out. Stoker loves it and has become much stronger. True, we still climb about 50% slower than I would on my single, but so what? We have fun. As far as singles go, we ride a little differently than I would on a single. We get aero and drop them on the descents, vanish on the flats, and then sometimes they catch us on the climbs and sometimes we wait for them at the top. If there's no big climb coming, we just ride with the group normally. For major pass climbs, we leave a little early. On small rollers, we accelerate from the back, pass everyone, and go like the devil on the bump. When we go past the lead rider with a 10 mph speed differential, no way will they grab on. It's a little weird, but they'll get used to it. Use the Force and deny them the Vortex.

+1

waynesulak 06-20-14 11:46 AM

Everybody has their own value system but a couple comments:

- I get very frustrated at slow climbing speed unless I forget about how fast I would be climbing on a single. Might as well think about how fast a whole different person would climb. It is just not comparable to most couples' speed. If it is then you have a very fast stoker.

- My wife/stoker would never sit on a tandem with an electric motor. She would rather not keep up than ride with a motor in a group.

- For us the best idea is to get a slower group or ride alone. We have done both.

- A few times we actually met my usual single group and started with a head start or used a prearranged shortcut while the group tried to chase us down. This can work out to be very fun as the group has a rabbit to chase but extreme care has to be taken calculating the handicap. If you have a route history of GPS files on your tandem alone to compare to group GPS files it can be done. Somehow my stoker has no problem with this. In fact I think she has worked harder and longer on these rides than any other type of ride.

colotandem 06-20-14 01:51 PM

Quote:

Originally Posted by Carbonfiberboy (Post 16866724)
Stoker power is the way to go. I almost never ride my single anymore. Why would I train myself and not her? If I go out, Stoker goes out. Stoker loves it and has become much stronger. True, we still climb about 50% slower than I would on my single, but so what? We have fun. As far as singles go, we ride a little differently than I would on a single. We get aero and drop them on the descents, vanish on the flats, and then sometimes they catch us on the climbs and sometimes we wait for them at the top. If there's no big climb coming, we just ride with the group normally. For major pass climbs, we leave a little early. On small rollers, we accelerate from the back, pass everyone, and go like the devil on the bump. When we go past the lead rider with a 10 mph speed differential, no way will they grab on. It's a little weird, but they'll get used to it. Use the Force and deny them the Vortex.

+2

I will add that you CAN get faster. Our best time on a local climb (6-8% grade for 4 miles) is nearly as fast as I could climb it. It is surprising. My stoker is very strong and quite driven, so I'll say that I'm very fortunate. Now that I think about it some more, maybe she is the strong one and I'm just holding her back??? :rolleyes:

One comment regarding the originaly poster's question. I believe that Santana has a prototype electric assist tandem that may or may not be ready for prime time. You should inquire.

reburns 06-20-14 02:58 PM

Quote:

Originally Posted by colotandem (Post 16868405)
+2


One comment regarding the originaly poster's question. I believe that Santana has a prototype electric assist tandem that may or may not be ready for prime time. You should inquire.

We were at a Santana rally recently where Bill and Jan rode an electric assist tandem. I'm sure you can get more info from Bill McCready.

waynesulak 06-21-14 04:28 AM

For better or worse Bill M. Does think outside the box.

DubT 06-21-14 12:25 PM

Here are some things to think about. What does your stoker want? Does she enjoy riding with groups of singles and trying to keep up. Would she prefer to ride the tandem with you as a means of building a better relatonship. She may not be comfortable in a pack situation, mine is not! We will ride by ourselves 99% of the time and that is the way we prefer to ride. We thoroughly enjoy riding the tandem but at our pace, we are both retired so we can ride when we want to, where we want to and we ride nearly everyday.

We did ride a tandem rally and one team had the electric assist that you are talking about, from what I heard they really like it and it did a good job for them. If I was looking at a particular electric motor I would be calling the manufacturer.

Remember that for the long haul you must keep your stoker happy!

Blade-Runner 06-21-14 05:09 PM

This thread has got to off topic, I didn't ask to be talk out of it, I asking for info from those who have valid input on electric motors on tandems.

drbenjamin 06-26-14 05:39 PM

Quote:

Originally Posted by Blade-Runner (Post 16871003)
This thread has got to off topic, I didn't ask to be talk out of it, I asking for info from those who have valid input on electric motors on tandems.

Yeah it really did. Blade-Runner, I am in the same spot as you. New to tandemming, I ride 4000+ miles a year. My wife has tachycardia and cannot have her heart rate go above ~120, so on long climbs she cannot pull her weight. I can get us over a few hills but not the 60 mile 4000 ft elevation rides that I love to do. I am really enjoying riding on a tandem with her, so I've been researching a motor to get us up hills, with no assist on the flats. Here's what I know
1) I will use a mid-drive setup, one that provides power to the crankset so that the bike gears allow the motor to spin quickly even if the bike is moving slowly. This is critical - at low RPM the electric motor efficiency drops so that its actually an electric heater. Hub drives (even geared ones) are no good for climbing for this reason
2) This year a couple of excellent aftermarket kits have come out. One in particular is being modified and resold by a guy "lightningrods", index.gif He makes his own brackets and is working w/ me to allow the kit to drive the captain's crankset. It is similar in concept to a motor called the stokemonkey, but the latter has a large motor that I don't think will fit on our tandem
3) This stuff is not cheap - the motor will be ~$600 and the batteries the same or more
4) There is a forum called endless sphere http://endless-sphere.com/ where there is a ton of info on e-bikes.

Hope this helps and good luck w/ your search!


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