How does cruiser bikes with 1800-1900cc engines has a top speed of only 120-130kmph like Indian Chief Dark Horse while this speed is easily achieved with bikes with 250-350cc engines ?

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How does cruiser bikes with 1800-1900cc engines has a top speed of only 120-130kmph like Indian Chief Dark Horse while this speed is easily achieved with bikes with 250-350cc engines ?

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I don’t think that’s the case for all cruisers. For example HD road king has a top speed of 160 km/h, and even that is electronically limited, which means it could probably go faster. (Upon further research the Indian Roadmaster has a top speed of 184 km/h, the Honda gold wing 224 km/h.)

A lot of factors determine the top speed of a bike or car. Aerodynamics, gear box ratios/final drive ratio, designed purpose, etc. You’re right in that 250cc bikes will do 120 km/h, but just like an F1 car will do 320 km/h easily with a 1.6L engine while some cars struggle doing 220 with a 2.4L engine (think old Toyota camry.)

I suspect that despite the weight of most cruisers, the aerodynamics aren’t great on them, and they’re not sport bikes that are meant to be ridden fast; their drive ratios are probably also not designed for top speed but rather torque, for hauling its own weight and whatever passengers and/or luggage it has to carry.

Designing for a particular goal in mind.

Small displacement sportbikes are a lot lighter, and geared for maximum speed, not long life.

For those who can’t understand the whole question, [this](https://www.indianmotorcycle.com/en-us/chief-dark-horse/specs/) is Indian Chief Dark Horse.

A pretty beefy motorcycle, weighing in at about 650 lbs. empty, and as described, packing a near 1900 cc motor. As a cruiser, its gear ratio is designed for just that: cruising. A long lifespan at a moderate speed, making peak torque at only 2900 RPM, and an upright-aka non aerodynamic but comfortable to sustain for hours-stance.

Contrast a [300 cc sportbike.](https://en.m.wikipedia.org/wiki/Kawasaki_Ninja_300) Weighing in at only half as much for starts, designed with aerodynamics in mind, and with a gearbox made for maximum speed above all, blazing that tiny motor at 10,000 rpm wide open. That motor may be smaller in displacement but it’s spinning three times faster, which makes up for a lot-at the cost of also wearing out faster.

Big displacements mean big parts, they like to move slower but have a large burnchamber, so they produce lots of newtonmeters.

Gearing and wind resistance.

I’m not much of a bike guy, but I know cars. My 125 HP Plymouth Sundance could pull 115 mph in 4th. I was limited by tires. They got squishy at that point. My 190 HP minivan at the time could pull 115 mph but ran out of gears. My Dodge Neon could do 125 with 135 HP limited by gears in 5th.

My buddy had an old Suzuki 1200. That one could pop a wheelie in 5th gear. It was so fast that he got rid of it. It wasn’t safe. My uncle bought one too at one point. He also got rid of it because it just wasn’t safe. Too fast. The right gears, the right shape. It just flew.

All machines work differently. Technically, you only need 15 horsepower to hold 55 mph in any standard car. You could probably do it with much less on a bike.

It’s all in the gearing.

Let’s just focus just on the engine aspect. You need horsepower to go fast. Horsepower is measured as work done over a period of time. Let’s pretend a big engine and small engine are hooked up to devices to carry and transport bricks. The big engine can carry 90 bricks but it takes longer to transport since you can’t spin the engine too fast or it will explode. The smaller engine can’t do a lot of work (maybe carry 45 bricks) but it can transport it faster since you can spin the engine faster. Let’s say it can make 2 trips for every one the big engine makes. After 1 hour, you’ll see that both have done the same amount of work. Bottom line, a smaller engine can do as much work as a bigger engine but you have to make it spin faster (rpms)