How to Correctly Choose Spare Parts and Add-ons for Your Ebike

No other means of transport, or leisure companion, is as closely related to our body, our habits and needs as ebikes. Consequently, we need ebikes spare parts not only to replace worn-out elements, but more often to better harmonize our ebike with our riding needs. Moreover, since ebikes constantly evolve, updating some components can improve their performance. In the end, to best enjoy our ebike, mastering spare parts knowledge is paramount.

Follow the links here to discover how to correctly choose each spare part, in alphabetical order:

Batteries | Brake pads | Chain rings, cassettes and chains | Crank arms | Discs | Displays | Lighting | Range extenders |  Shifters |  Spokes | Tires

Searching criteria

Your ebike exact model and model year are essential to identify compatible parts. The exact type of motor can be sufficient to correctly choose transmission parts, displays and batteries. If you don’t know what motor your ebike features, just search on Google, filling in your ebike model and model year. Bosch spare parts often refer to the generation of the motor, which is as follows: Gen1 from 2011 to 2013, Gen2 from 2013 to 2018, Gen3 from 2018 to 2020, Bosch Gen4 from 2020 to 2024, Smart System from 2022, Gen5 from 2025. There are exceptions, though. See teh image below.

AI can help

Try to ask ChatGPT what part fits. It works well, with some caveat.

Choosing the right battery

There is a specific battery for every motor, although sometimes you can choose between two different wattages. In case of doubts, measures of your battery emplacement should correspond to the new battery. See also  Tips to Increase Your Ebike Battery Duration and Range. Choosing the Right Battery. Bigger is Better? Not Always! and Dual Battery, Range Extender Or None, How to Choose.

Finding a compatible range extender

Not every ebike is compatible with the range extender of the same brand. Compatibility depends on the type of motor, and also on the possibility of installing the range extender on the frame with attachments, fastening bolts, etcetera.

Choosing the right shifter and or a derailleur

You can always install a shifter and or a derailleur which is different to the original, provided it’s compatible with cassette, chain and chain ring. See Correctly Using your Shifter Greatly Improves Your Ebike Experience and Cleaning and Lubricating Your Ebike Chain and Shifter, Tutorial: How to Efficiently Adjust Your Derailleur.

Chainrings, cassettes and chains

They must be compatible with each other. Check number of teeth and number of speeds. You may mount a bigger chain ring, then you will have to find a longer chain. The chain should be replaced so that its number of links can correspond to the increase in the teeth of the chainring.

Chainrings

It’s quite common to want a larger chainring. To make the right choice, note the following: carefully check its compatibility with the type of motor. Check the offset of your original chainring; it must be identical to that of the new chainring. If you have a boost hub, 148 x 12 mm, choose a boost chainring or at least one that has the necessary offset to be in line with the middle gears of your cassette. If you buy a chainring that is not direct mount, consisting only of the ring, you will need to buy a spider with the correct offset. To attach it, you will need to measure the BCD (Bolt Circle Diameter) of a 4-arm chainring, which is the distance between the centers of two diametrically opposite holes. The BCD of a 5-arm chainring is the distance between the centers of two adjacent holes.

To choose the number of additional teeth, check that the chainring does not touch the chain guard or the front derailleur if you have multiple chainrings. Look for a number of teeth that allows you to ride as long as possible with the middle gears of the cassette. For example, if the cassette has 11-13-15-17-19-22-25-28-32-36 teeth, and you prefer to ride with 17 teeth, with a chainring with 2 or 5 more teeth you can use the same gear ratio with the 19 and 22 teeth gears respectively, which are more central. The more you use the gears at both ends of the cassette, the more your chain will be slanted, increasing friction with the gears, wear, and noise. The chain should be replaced so that its number of links matches the increase in chainring teeth.

See Tutorial: Changing the Transmission of Your Ebike: Chainring, Cassette and Chain.

Choosing the best tires

It’s essential. Original tires are not always best fitted to your writing habits. See Correctly Choosing Tires for Your Ebike, for Road or Trail, Do-it-yourself Bike Repair on the Road: Tubes & Tubeless Tires, and Repairing by Yourself a Punctured or Damaged Tire on the Road.

Replacing and tightening spokes

If replaced, they should be as similar as possible to the original ones. See Ebike Spokes: How to Choose, Tighten and Replace Them, and also straighten your rims, provided they are not too bent. Also: How to Replace a Spoke on the Road or in Your Workshop

Disc brakes

Larger disc brakes will hardly fit, unless there is a specifical adapter for sale and calipers fit.

Crank arms

To choose the right crank length, you can read Choosing the Right Crank Arm Length to Get the Best of Your Ebike. Keep in mind that long cranks increase the risk of hitting the ground with the pedals when cornering. You also need to consider the Q factor, which is the distance between the insides of the two cranks, which is twice the chainline. It’s normally 168 millimeters, sometimes 156 mm, and varies depending on the crank offset, which is stated on our website (if not, ask). Also consider the length of your legs. For example, if they are short, a Q factor that is too wide could cause problems in your knee joints.

Saddles

To understand the importance of choosing the right saddle for your electric bike, calculate the ratio between the square footage of your saddle and the square footage of your favorite chair, and compare it with the time you spend on your chair and the time you spend on your saddle, respectively. At least three times as many hours per square centimeter on the saddle, right? Then you can decide whether or not it’s worth reading this brief tutorial on choosing a saddle. See What saddle choose for your ebike? Sleek & light, or bulkier & comfortable?

Replacing brake pads

Worn brake pads squeak and squeal, and their metal backing will scratch the disc. They must be replaced before their metal backing damages your discs! Pads should be suitable for the type of brake, normally indicated in the ebike specifications. Creating paths deliver better breaking power then metallic ones, but we’re out quicker. See How to Service Disc Brakes and Replace Pads.

1. First, tighten the brake cable adjustments on the levers clockwise. This will allow you to use them to tighten the brakes when the pads are slightly worn.
2. Remove the disc brake caliper, which is normally secured by two hex nuts. The pads are attached by a small pivot that passes through their upper hole. It is normally screwed in place and must be removed to take out the worn pads.
3. Now, using a flat tool, preferably made of plastic, push the brake piston(s) all the way in to maximize the space for inserting the pads from below.
4. Insert the brake with the pads onto the disc. If it sticks, you have not pushed the pistons far enough apart. Insert the pivot.
5. Tighten the caliper with the two nuts, screwing them in simultaneously. Activate the brake lever five or six times to restore pressure to the hydraulic circuit.

Choosing compatible displays

Each display is compatible exclusively with certain specific motors and control units.

Lighting

First, headlights and taillights must be conveniently fastened to handlebars, racks, seat post and the mud guards. Adaptability must be carefully checked out. Most lights are compatible only with certain motors. Plugs and cable connections to the motor must be compatible. Their energy consumption is minimal, from 4W to 12 w per hour.

Last but not least

When asking information about any spare part, keep in mind that your professional interlocutor needs as much relevant information as possible. Year and model year of your ebike are essential.