For example: If your drive wheel is 100 mm running at 3000 rpm motor, then the speed of the 12 mm wheel will be 25000 rpm. Therefore bearings will not last long if you don't have a way to reduce the drive wheel speed. It's a must that small wheels operate a much lower belt speed.
The Bearings can be replaced when they get worn-out. You will be able to easily source them cheaply. At this high speed, there is no difference between cheap and expensive bearings. Set Includes the following wheels dimensions.
All wheels are 65 mm wide made from Steel. The item "Pulley Wheel Belt Grinder Small Wheel Holder Set Fits Smart Grinder S1, L1" is in sale since Thursday, May 2, 2019. This item is in the category "Business, Office & Industrial\Power Tools\Grinders\Grinders". The seller is "smart-grinder" and is located in Skierniewice. This item can be shipped worldwide.