Converting a bike – hardtail vs. fully

First things first: The main difference between a hardtail bike and a fully bike is that the hardtail does not have a rear suspension. Due to the lack of a shock absorber, it is “hard” or unsprung.

In principle, (almost) every bike can be converted. Some are easy, others require one or two adjustments. However, you should pay attention to a few things beforehand:

• Measure the bottom bracket width so that the right motor can be selected
• Check battery location (where is the battery mounted?)
• Determine the right chainring so that the chain line also fits after the conversion

The easiest way to convert is usually with a hardtail, as these usually offer enough space for the battery in the frame (1). Depending on how much the swingarm (2) is tapered, spacers may need to be added so that the mid-motor can be mounted correctly. The chain line should also be taken into account so that the chain does not run permanently at an angle after the conversion. We will write a separate blog post about this. The geometry of the down tube is also important in this area: on a hardtail, the down tube usually rises quite quickly. This ensures good ground clearance after the conversion. To select the right mid-motor, the bottom bracket width (3) must also be measured. This is important so that the axle length of the motor matches the frame width of the bottom bracket.

Fully bikes usually have the disadvantage that no bottle cage battery can be placed in the frame triangle due to the suspension. Alternatively, this battery can be mounted “hanging” on the down tube (no. 3 in the following pictures). It is also possible to use a custom battery in the frame triangle or a backpack battery.

With full suspension bikes, the frame geometry in the bottom bracket area should also be taken into account for the correct selection of the mid-motor: On some bikes, the down tube usually runs horizontally for a few centimeters in the area of the bottom bracket before it bends upwards (1). If you choose the Bafang BBS01, BBS02 or BBSHD mid-motor, it “hangs” quite low as it cannot be turned upwards (low ground clearance). If you mainly ride “onroad”, then this can be neglected. If, on the other hand, you ride your bike a lot “off-road” and also want to overcome steps, you should choose a different frame for this – such as the following marking 2. This means that you also have sufficient ground clearance when choosing the Bafang motors. This is not very important when choosing CYC X1 mid-drive motors, as this mounting concept also allows the motor to be mounted in the frame if necessary.

We hope that this article has provided you with a few points about the conversion and a comparison of the geometries. If you have any further questions, please feel free to contact us (welcome@fasterbikes.eu).

Have fun with the conversion!