Shimano Nexus 3 and 4 G T belt drive

Discussion in 'Transmission / Drivetrain' started by rananthan3, Jun 15, 2015.

  1. rananthan3

    rananthan3 New Member

    I purchased a Shimano Nexus 3 speed internal hub along with the 4G T belt drive transmission. I am trying to calculate the final drive ratio given that the Shimano rear sprocket has 19T

    I have a 20T belt pulley driving a 100T pulley that is connected to a 12 tooth drive sprocket. This is connected to the 19T rear sprocket via a chain.

    The gear ratio for the nexus 3 speed can be found here:

    Gear 1: 0.733
    Gear 2: 1
    Gear 3: 1.364

    Final drive ratio = (100T / 20T) * (19T / 12T) * internal hub ratio

    Gear 1 drive ratio : 5.80
    Gear 2 drive ratio : 7.92
    Gear 3 drive ratio : 10.80

    These seem low which would give slow acceleration and poor hill climbing but high top speed. Has anyone experienced this?

  2. The_Aleman

    The_Aleman Active Member

    You're definitely going to need to reduce that further using a jackshaft or a much larger rear sprocket. You don't have near enough gear reduction.


    I doubt that is even usable. 1st gear is much much taller than my own setup's 5th gear (14.62:1) and I'd smoke my clutch taking off in that gear.