Where is the best place for an ebike battery?
As the battery is a heavy component of the bike, it will significantly alter the weight distribution of your ebike. Depending on what the bike will be used for, some placements can be better than others.
The rear cargo rack is an excellent place to hold your battery, there is a reason why when people go touring they mount their luggage at the rear of the bike - it keeps it out of the way. This mount has its drawbacks however, particularly if the bike has a rear hub motor. As all of the additional weight will be towards the back of the bike, lifting and storing the bike can be awkward as it will be very unbalanced. If you are commuting or touring with additional luggage on the rear rack this imbalance will only be emphasized. Additional weight at the rear of the bike may pose a hazard if turning at high speed as the back wheel will be more susceptible to sliding out like a muscle car. The only drawback to placing the battery here is that the front and rear of a bike experience the greatest amount of shock and movement when riding over things and placing a battery here may make it susceptible to damage from vibrations or sharp changes in position. The area in the middle of the frame will move the least when the front and rear wheels go up or down.
A popular place for a battery mount is in the middle of the frame similar to a water bottle mount or some higher end models house the battery in the tubing of the frame. This position provides great balance to the bike as the weight is located very near to the center of the bike. Mounting the battery here requires it to be slim and not jut out much wider than the frame to prevent the rider knocking their leg on it while pedaling. Mountain bikers prefer this position as they rarely ride on flat ground and require the bike to be as equally balanced as possible
The best position we have found to mount the battery is along the downtube underneath the saddle. As this is where the force of the rider’s weight is applied through, the additional weight will affect the bike as if a heavier rider is using it. There is ample space to store a battery here without interfering with the gears or tyre, particularly if the ebike is a hardtail (without rear suspension). This location also allows for the battery to be easily removable.
As the battery is quite an expensive component of the bike, replacing it before the end of it’s natural lifespan can easily be avoided. If you know that you will be riding off-road or on uneven terrain, checking out the battery housing and placement is definitely worth doing. If the battery is housed in or at least mounted on pads to absorb shock it will go a long way in preserving it and keeping it out of harm’s way when you ride on bumpy ground.