Video summary

Why Don't More Motorcycles Have CVTs?

Main summary

Key takeaways

Technology

Summary: Why Most Motorcycles Don’t Use CVTs

Core question

Why do most motorcycles not use CVTs (continuously variable transmissions), even though CVTs work well on scooters, snowmobiles, ATVs, and some cars?

Dry theory: What a CVT / variator does

A CVT/variator is an automatic, stepless transmission that transfers engine torque to the wheels while keeping engine speed relatively stable.

Unlike gearboxes, there are no discrete gear ratios. Instead, the ratio is adjusted smoothly during acceleration and deceleration.

Why transmissions exist at all

Combustion engines can’t deliver usable torque everywhere; they have an optimal working RPM range. A transmission helps the vehicle to:

  • start moving from standstill
  • drive slowly efficiently
  • accelerate to higher speeds
  • maintain speed under different loads

If an engine produced high torque from 0 RPM to max RPM (like an ideal electric motor), then a transmission might be unnecessary.

How scooter-style CVTs work

A typical CVT uses:

  • two variable pulleys
  • a belt between them

As the vehicle speed changes:

  • the drive pulley contracts/expands, shifting the belt onto a different effective diameter
  • the driven pulley does the opposite

This continuously varies the gear ratio, controlled in simpler designs by centrifugal weights/rollers, and in more advanced systems by mechatronics.

Result: output torque changes continuously.

Why CVTs are difficult on motorcycles (main arguments)

  1. Packaging / weight / size increases with torque Higher torque requirements mean CVTs must be bigger and heavier, which conflicts with motorcycles’ focus on low mass.

    • Example cited: a BMW maxi scooter (described around 63 Nm and ~60 hp) needs a “monstrous” variator size to transmit that power/torque.

  2. Efficiency loss

    • Claimed CVT efficiency: about 80–90%
    • Primary reason: friction between belt and pulleys
    • Typical geared transmissions: about 98–99% efficiency

Practical implication: losses are much higher with CVTs—framed as ~10–20 kW lost in a 100 kW comparison (versus ~1–2 kW for gears), making the system act like a heater (heat generation emphasized).

  1. Cost and maintenance CVTs are described as heavier, larger, more expensive, and more demanding to maintain than traditional gearboxes.

  2. Cultural / market resistance Motorcycling traditions and rider preferences are portrayed as a “cult,” with riders often reacting negatively to radical changes.

Net effect: due to torque/packaging constraints, efficiency, cost/maintenance, and rider preferences, manual transmissions remain the most desired on motorcycles.

Why CVTs are more acceptable on snowmobiles / ATVs

The discussion points to:

  • no shifting/gear-selection workload during off-roading
  • generally more space for the transmission than on motorcycles
  • cooling is less of a problem (relative to motorcycles)

Historical references: motorcycles with CVTs did exist

The video claims multiple CVT motorcycle examples across time:

  • 1911 – Zenith Grad(u)

    • A 6 hp model using a CVT/variator system
    • Rider action: adjusting a lever shifts the swing-arm axis to position the belt on the pulley
    • Claimed to perform well in high-speed hill climbs
    • Rivals viewed it as an unfair advantage; competition restrictions followed
    • By the 1920s, it was replaced by a cheaper traditional gearbox

  • 1912 – British variator motorcycle

    • A variator patented (in 1910) with variable pulleys (one on the engine shaft, one on the rear wheel)
    • As one expands, the other contracts to change ratio gradually
    • Claimed to break 60 mph and win a Tourist Trophy race (the year “1914” is mentioned; production discontinuation is stated as “1923”)

  • 1997 onward – Clyde Ridley’s automatic CVT-style motorcycles

    • Framed as “automatic transmission motorcycles” (not necessarily the same belt-CVT approach as scooters, but included in the broader CVT narrative)
    • Mentions early company model releases and:
      • “Autoglide” wording and a legal dispute with Harley-Davidson
      • settlement timeline: Dec 28, 2009, then bankruptcy filed next day

  • 2006 – Ridley 850

    • Said to borrow an engine and CVT from a predecessor scooter (noted as “Scooter 800”)
    • Mentions small power figures (specific values referenced) and a rider note that it heats up a lot

  • 2005 / 2008 – DN01

    • First shown in 2005, sold from 2008
    • Described as using a hydraulic CVT with electronic control, contrasted with the more common belt-driven CVT

Conclusion / stance

CVT technology is presented as technically impressive with real-world use cases, but the speaker concludes it doesn’t “belong” on motorcycles, mainly due to:

  • torque and packaging constraints
  • efficiency losses
  • cost and maintenance demands
  • rider culture and market preferences

Main speakers / sources (as given at end)

  • Crossmo channel (narrator/host) Historical figures/companies referenced: Zenith, Frederick Barnes, Ridley/Clay Ridley, Harley-Davidson.

Original video