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  1. #1
    mtbr member
    Join Date
    Feb 2005

    eTandem for OLD Folks

    I recently installed a Bionx D500 e-bike system on our Ventana ECDM Full Suspension 26" MTB-Tandem.

    D 500 DV - e-bike, electric bicycle systems | ridebionx.come-bike, electric bicycle systems |

    Bionx D500 DV - Electric Cyclery

    Our first ride was a 14 mile road loop with 1,000+ feet of climbs from our house. Although the real proof of the pudding will be a ride on the local technical off-road trails - my impression is that this system will be AWESOME for this application and help keep our OLD team on the trails a while longer.

    The essential requirement of a power system for Technical Off-Road Tandeming is smooth strong controllable torque at VERY low speeds - like 2 to 5 MPH (when crossing logs, climbing short but very steep inclines and traversing rock gardens that require a lot of power to maintain enough speed to balance and avoid getting stalled or stuck in gaps between rocks). The unique design of this new technology extremely large diameter hub motor really provides that LOW speed torque. The Torque Sensing Variable Pedal Assist makes it just as controllable as the human power that it is assisting.

    The display and controls are informative and intuitive. With the battery mounted on the bottom tube just behind the front cranks, the total system weight of 17 lbs. is quite low. Cassette drive makes gearing choices unlimited. (We have a 20/34 front with a 9 speed 12/36 rear and a BioPace captain chain ring). The icing on the cake is that the wiring is fairly simple and protected and the motor is virtually silent.

    E-powered range depends on which of the 4 Torque Sensing Pedal Assist levels is selected and on how much human power is applied. The bar that displays "Power Remaining" isn't precise but it indicated around 70% left after our 14 mile ride. Off-road power usage will be MUCH higher but it appears likely to last as long as our limited 144 year old human power.

    eTandem for OLD Folks-0313151557a.jpg

    Although not installed in this picture - there is usually a plastic waste basket mounted behind the stoker bars where our 13 lb pup Bandit rides! Me - the OFG (Old Fat Guy) plus Bandit weigh about 2X what our stoker the QOFE (Queen of F'ing Everything) weighs - so we're NOT a light weight team! I'll install an areo wheel cover on the back and make a fabric bag/cover for the lower triangle where the battery lives to be stealthy for the occasional MTB park rides we do.

    Although we still haven't gotten to give the eVentana a real off road test - we were so pleased with the system that we have now installed one on a 1990 Santana Rio and set it up for road riding with 26" X 1.25"+ 1.75" slicks. Bandit rides in a knapsack like bag hanging from the front bars. The 3 of us - OFG, Bandit and the QOFE have now taken it on 2 rides of about 32 miles with ~ 2,500 feet of climbing. Sunday we did a 42.5 mile ride, with 7 miles of dirt and 2,860 feet of climbing (per MapMyRoute). On all three rides the battery made it all the way BUT was about 99% used at the end! On the 42.5 miler, AVS was 12.8 which is several MPH faster than we could do in this terrain on our 700c Sovereign w/o the dog (IF we could even make it???)! The rig with racks, tools, etc. but no dog or water weighs a svelte 81 lbs! The gearing is 46/34/20 with a 9 speed 11-34, barcons and a BioPace front chain ring. We've only had to use granny once - when we stopped on a VERY steep section to avoid another stopped bike - but it is there IF we ever have to climb with a dead motor - UGH!

  2. #2
    Reputation: ki5ka's Avatar
    Join Date
    Dec 2006
    Well I sure as hell hope that at an average age of 72.5 years, my stoker and I are still rocking it like you two! Funny, I just sold our Rio 4 days ago! You're making me second guess that decision AGAIN.

    Love the color btw


  3. #3
    PMK is offline
    mtbr member
    Reputation: PMK's Avatar
    Join Date
    Oct 2004
    Sam, interesting. A friend here has gone electric assist on his single MTB. His only produces power as pedal assist. So if you don't pedal it does not assist.

    Someone else, don't know who has one of the higher powered full time electric MTBs. He destroyed some trails and rode like an idiot around others. It all ended ugly where they told him he was basically riding a motocross bike on an MTB trail that is closed to motorized vehicles. He will be in big trouble if he returns.

    Diana and Gabe Mirkin, of road tandem fame, are now riding a tandem recumbent on the road. They were having issues climbing and added some electric to it. Unless you count Bandit, they may have you beat. I think their combined age is 160 plus.

    All the best with it.

    Reps! We don't need no stickin' reps!

  4. #4
    mtbr member
    Join Date
    Sep 2010
    Keep on rockin', Sam.

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