Announcement

Collapse
No announcement yet.

set of gears for 15% slope

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

    set of gears for 15% slope

    Hi all,
    I will be using a 29" 2.15 tires bike with BBSHD under 52V.
    I will get a 11-34 rear gear set and I was wondering what to get as a front chain wheel. 42 or 46.
    I will get the maximum power under a 8 to 15% slope for an elevation gain of 1600 feet.
    I was about to go for the 42 teeth but then I was thinking it would be maybe better to keep some rear teeth to catch the chain power and I am thus thinking about a 46 teeth.
    did you experiment the wear of the chain and teeth ?
    I would expect to ride at 80 rpm legs turns with 46-20 teeth to 25 Km/h (about 15 miles/h). some software are then calculating a power of 1200W. so I will be close to this setting.
    more over the 20 teeth gear will be in the middle of the rear gear set. so chain might be in line.

    thank you for you opinion and feed back on this choice !


    #2
    The widest capability for many people, including me is a 42T chainring and a 11-46 rear cassette.

    Some people need motorbike road speed or to climb insane gradients and will go for bigger or smaller chainrings.


    Comment


      #3
      If you want to stay away from your 11 tooth sprocket go with the 46 tooth chain wheel.

      Comment


        #4
        I would recommend the smallest chain ring possible because you mentioned a 15% climb.

        Comment


          #5
          thanks for your answers. I will reword my question. I want to keep quite big rear gear to have a safe use for the chain.
          my question is about feedback. do you think I can get to 15% using a 46-20 gear or 46-30 on a 29" wheel (see the chart attached with the speed for 80 legs rpm). or is it too big.
          total weight will be 230 pounds (105 Kg)
          I have no idea if the BBSHD is powerfull enough. I guess I do not need 42-42 because I get to this slope with road bike with such ratio (28-28).

          Comment


            #6
            tommies juste said in an oter post, that the best operating point for the BBSHD is around 120 rpm.
            so maybe the 42 teeth is the best then. target is about 25 to 30 Km/h.
            Click image for larger version

Name:	image.png
Views:	1
Size:	10.8 KB
ID:	64802

            Comment


              #7
              Don't bother with anything larger than 42T unless both you and the bike are very light and you have flat ground to burn over as well as hills. My 42x11T is great for allowing me to pedal along on PAS at 28 mph with the bike (BBSHD). However, my top speed on 42x11 is the same as it is on 42x13. 42x15 only loses about 2 mph. So... the motor is lugging at 42x11 and the only reason it is usable at all is to accommodate my desire to pedal... not because its a smart gear for the motor.

              I am building a bike that will live in steep hills right now. Using a Shimano HG400-9 cluster in 12-36. I expect to stay off the 12 and live in the lower gears. 42x36 is fine and with a long cage derailleur it will be simple to wrap the chain I need to utilize the full range (I use a KMC x9e with 136 links and take off about 8 or 10).

              Comment


                #8
                thank you MoneyPit. I start to understand the spirit and way to use the motor at his best rate.
                so 42 will be my choice. I have 11-34 and will start with that and see if I change for a 12-36.

                Comment

                Working...
                X