When your kart is handling badly, you look to make more aggressive adjustments. Think axle & seat. But when you’re just trying to fine tune your setup, hubs make a smaller difference that won’t drastically change the balance of the kart.

Let’s first look at the different adjustments we can make with our hubs; the length & material of the component.

Hub Length

Depending on what you’re trying to achieve, hub length plays a pivotal role in the amount of grip a kart will have.
If you are changing from your standard-length hub (cadets around 45mm & seniors 90mm) a shorter hub will release grip. The shorter hub will allow the axle to flex more (as there is more axle showing). A longer rear hub (often referred to as a “double knuckle”) will increase the rear grip by stiffening the axle. We see the “double knuckle” hub used in the wet conditions predominantly and sometimes in the shifter category to help with rear stability and traction.
The hub length can also be adjusted on the front of the kart if drivers aren’t using a bearing rim.
The same principles apply as the rear, a shorter front hub will reduce steer, so best utilised if the front has too much oversteer, and you want the steering to be less responsive. A longer front hub will increase the front steer, so best suited to wet conditions or if the kart has too much rear grip and is understeering. If your steering becomes heavy, a longer front hub should help reduce that.

Magnesium vs Alloy

Hubs are also manufactured in different materials to alter the handling characteristics.
Some karts are distributed with magnesium as a factory setting (Kart Republic, CRG, OTK) and others are sent out with alloy components (Arrow, Parolin).

Magnesium components main advantage is to reduce the heat retained in the part. So, in this instance we are discussing the hubs. More load is transferred to the rear hubs as there is more g-forces with the engine, axle, weight, and tyres. If your kart is gripping up too much, bouncing, losing pace the longer the session goes on, then a magnesium component over an alloy hub will provide a real benefit.

If your kart takes too long to get grip, or its wet, or you’re a cadet driver, then an alloy hub might be sufficient to provide that additional grip over the magnesium.

In past races, I have been known to use alloy rear hubs (to increase grip) and left magnesium front hubs as this provided the best balance on used tyres, so it isn’t a set rule you need to adhere to.

One thing I would recommend, is that if your kart was designed around a certain material (magnesium with OTK) then try sticking to that material first and alter other areas of the kart to add or remove grip. The karts were tested, manufactured, and designed with this material, so it’s advised to try stick with the factory settings where possible.