No announcement yet.

Will this idea work?

  • Filter
  • Time
  • Show
Clear All
new posts

    Will this idea work?

    TLDR is below
    Right now I own a Look 795 Light RS 2018 very similar to

    I just got a new job and my new commute is 31 miles each way. I still want to bike so I can have an excuse not to have to go to the gym but, at 31 miles my commute will take me about 1.5-2.5 hours each way. I average about 12-18 MPH depending on how I feel that particular day. I do have some hills to my apt in SF but, nothing major thankfully.
    I do want to get an e-bike but, don't want to drop 7k on a Domane+ but, the cheaper e-bikes are either limited by range to about 20 miles at a high speed or by the speed with the motor cutting off at 20mph.
    I want a bike that can go the 31 miles with the max assist and reach speeds of at least 28-35 MPH. Basically I want to cut my commute to an hour each way with a high level of assist.

    I am thinking of adding the following to my bike (
    I am 99% sure the triangle battery will fit, I already have a triangle bag on my Look so it shouldn't be a problem.

    My concern is the carbon fiber of the bike. Will that hold up to the power of the motor day in and day out?
    I was thinking of buying a cheap 6KU bike off Amazon and converting that instead but, I really do enjoy riding my Look and want to keep using it.

    Any thoughts?

    IMHO, that bike is a very poor choice to convert with those very heavy conversion components. At the very least and at the speeds you want to run, unless you're riding on a closed access smooth bicycle trail the tires/wheels won't be up to it, and the brakes aren't much behind.

    That bike is excellent for its designed purpose. High power electric bikes have very different design needs (overly heavy duty, to start).

    P.S. - if I had 7k to drop on a high power electric commuter (and a safe place to put it while at work) I'd probably buy a Watt Wagon, which would also fill most of my errand needs.
    Last edited by ncmired; 08-24-2019, 11:42 AM.


    • taco3468
      taco3468 commented
      Editing a comment
      Well my commute is almost all well paved suburban streets. Even now if I pedal hard I can overtake cars due to the 25 mph limit.

      What about something like this

    • ncmired
      ncmired commented
      Editing a comment
      I'd say, "barely better" but light bike seems the platform you want to go with, so ...

      First off, the BBSHD is, I think, generally not considered a nice "ride along" motor. It doesn't have torque sensing, and its optimal cadence is sky-high.What's your optimal cadence? Hopefully well past 100 or the BBSHD will struggle helping, as it's optimal cadence is up around 140 (design flaw). A single speed drivetrain will exacerbate this weakness.

      For the battery, if you can significantly contribute at the speeds you want to go, a 14AH (better 17AH) battery will get you one way with some spare. Can you charge at work (whole bike or removable battery)?

      On the 6KU, do you have any idea what the chain line is? I'm guessing it has a 110-120mm O.L.D. rear hub. For a BBSHD (with Luna's Eclipse chain ring), it's best not be below 45mm (assuming a 68mm BB). You might be able to change out the 1/8 chain for a more flexible 3/32 if chain line turns out to be an issue.
      Last edited by ncmired; 08-24-2019, 01:55 PM.

    • taco3468
      taco3468 commented
      Editing a comment
      Can you expand on what you mean by "light bike"?

      Do you have a motor that might fit my purposes better? I was not planning on installing a throttle on the BBSHD but, if it isn't the best motor for my purposes can you suggest one? My only desire is it be a mid-drive motor that can meet my commuting needs. I went with Luna because the other motors on Amazon and Ebay all seem kinda unreliable or cheap and ive heard good things about Luna.
      I've never used a bike computer or tried to track my cadence. I've always just put in whatever effort I wanted or needed throughout a ride.

      I really don't know anything about the 6KU aside from it has the geometry I like once i put drop bars on it, and its cheap, and aluminum. I thought a fixed gear would work better with a motor since its simpler?

    Don’t get discouraged. Just keep researching, this is a great site for it, and you will find the right setup for yourself. Personally I ride a BBSHD on a cruiser bike. It’s a fun pedal assist bike at low speeds and basically a moped at higher ones.
    I use it for errands around town. I’m not really in it for the exercise, just a convenient vehicle I can bop around town on and throw in the back of my truck. It saves me a lot of time to be able to park on the outskirts of town, hit all the spots I need to go on the bike, and not have to drive around in slow ass traffic place to place.


    • taco3468
      taco3468 commented
      Editing a comment
      Building a DIY bike seems to be a much more complicated endeavor than I originally imagined. Im not discouraged but, a guide would be nice. Most guides are for DIY fat/mtb/cruisers but, nothing for high-speed road bikes.

    I wouldn't put a bbshd on a road bike. You will be under tired and under braked. As an alternative I used a Lightspeed Unicoi, It was designed as a softtail (1” rear suspension) mountainbike. The goal was an ebike alternative to my road bike. Also a cushier ride. It came with a 80 mm front shock, which I recently swapped out for a carbon fork. Mavic Crossmax wheels with tubeless 2" tires. Weight without the motor is 23 lbs. I added the bbshd kit and use the mighty mini battery. Weight is 40 lbs. Currently setup with a 42T Luna Elipse and Sram 10 speed with a 11-40 rear cassette and Shimano disk brakes. For more stopping power you could go with 4 piston calipers. While I use the gear sensor, I don't use the ebike brake cutoff, that gives you more brake choices.
    Now that Luna offers bigger ring gears you should be able to get the max your after. I'd also get the Luna black box for programming ease.
    This is an older shot with the suspension fork.
    Click image for larger version

Name:	updates small.jpg
Views:	391
Size:	174.8 KB
ID:	92294


      'Morning all;

      Here's a watts versus speed graph, which I hope will illustrate part of the speed problem:

      Click image for larger version  Name:	file.jpg Views:	1 Size:	91.6 KB ID:	92300

      taco3468 would like to go nominally 30MPH. For simplicity, let's just say he needs 1KW one way or another - 5 times what he can probably consistently generate just pedaling. I suspect he'd really want to go even faster, in hopes of travelling the 31 miles to work in an hour. Nothing wrong with hoping!

      So, using a, at least 1KW-capable mid-motor, his bike's drive train, frame, wheels and tires needs to be able to absorb, say 1500 watts (just a little overhead) of misery, with no suspension, at speed, over bumps. He'll need to add about, what, 22lbs of motor and battery to make the range with a little overhead.

      Road and fixie bikes tend to focus on low weight and just enough strength components. What I look at first (and cringe) are the wheels - on my first build using a typical Taiwan special, that's what failed first. 11-speed chains running on superlight cogs and chain rings worrry me next both have caused others here issues.. Finally, stopping from significantly higher speeds draw me to the brakes and tires. Tires also matter when looking for ways to reduce the higher road impact pressures.

      As an alternative to a road or fixie bike but with drop bars, I'd start looking at cyclocross bikes, and/or like Harold chose. 'Bents would be on the table, too. IF the terrain is flat, for the speed desired, I'd also investigate high power direct drive hub motors.

      P.S. the graph also illustrates what beasts the hour record holders are/were.
      Last edited by ncmired; 08-25-2019, 07:01 AM.


      Yes, the Cinelli fits the ebike conversion needs much better. A few things:Best of luck on your build, and please post how it goes!
      Last edited by ncmired; 08-26-2019, 08:48 AM.


        It's been 2 years since this thread began- probably too late to add my 2cents. I recently converted my Sycip with a Tongshen tsdz2 motor. It's middrive, torque sensed. The 750w gives me more power than I need. The 860c display let's me see my cadence and the motor speed (among other data). If my cadence is too high, the motor speed turns red so I back off. I have a 42T chain ring : a 50T ring would keep my cadence lower and give me 35mph speeds. Only 26mph with my 42T before I get to red zone.
        I love the 860c display but it is quirky. If pedals rotate while it's waking up the motor doesn't work. It has 20 assist levels. Lower and higher than other displays.
        . Hope you are happy with whatever setup you decided on.