Query: “I have this go kart and I want to make the rear tires bigger. If I change the diameter of rear sprocket so that it increases correspondingly with the rear tire, will the performance of the go kart suffer? In other words will the go kart go slower than before and will the go kart have really poor off the line acceleration?”Good query, I’ve usually considered that myself. I’ve usually stated that the rule of thumb for a go kart to have optimum efficiency is to have the rear sprocket be almost 85% of the rear wheel diameter. The query is, does that apply only for 12 inch diameter wheels or does it apply to 16 inch rear wheels too?The reply to that query might shock you. It shocked me. Once I ran by means of the calculations a humorous sample emerged:- A 12 inch diameter tire with a 12 inch diameter rear sprocket yielded a pace of 22 miles per hour at 7.three toes per second squared of acceleration.- A 16 inch diameter tire with a 16 inch diameter rear sprocket yielded a pace of 22 miles per hour at 7.three toes per second squared of acceleration.I believed that was faulty so I ran an entire slew of tires sizes with corresponding sprocket sizes and nonetheless got here up with the identical numbers.So the reply isn’t any. No, your efficiency won’t undergo should you enhance your sprocket dimension correspondingly with the wheel dimension.What’s going to occur if you don’t enhance your sprocket dimension is that the clutch will grow to be over loaded and smoke. The go kart would require pushing to begin and can have horrible low finish efficiency.However should you enhance the diameter of the sprocket in order that it’s 85% of the rear tires diameter, the efficiency ought to keep almost fixed.That’s an surprising end result, however one you possibly can rely on if you’re designing a go kart from scratch. The rule of thumb stands: “The rear sprocket should be nearly 85% of the rear tire size for optimum acceleration and speed performance.”The belt drive system for instance is sort of depending on this relationship. The reason being that the drive pulley for a belt drive will be fairly massive, 1.75 inches in diameter, and requires that the rear pulley be as massive as doable.Within the case of the wooden go kart that I designed, with a purpose to maintain the ratio a easy one to 1 system (versus including a jack-shaft) the rear pulley needed to be the identical dimension because the rear tire. I used to be capable of get by means of this drawback by making a wooden pulley which was sturdy sufficient to deal with highway situations, low cost sufficient to make myself and better of all gave the efficiency that was wanted for good acceleration and general pace efficiency.
