Especially those who want to take older e-MTBs on long tours in steep terrain should take a closer look at the gear ratio. Because if you can still conquer steep climbs in Eco mode thanks to lower gears, you will save a lot of battery power. Incidentally, the conversion to lower gears is relatively harmless for private individuals from a legal point of view. Dealers should check with the bike manufacturer.
Converting the cassette on an e-bike
This is how it works: Firstly, it is best to clamp the e-MTB in the assembly stand. Be careful with carbon frames: It is better to pull out the seat post slightly and clamp it to the seat post. If you don't have an assembly stand, you can also turn the bike upside down (be careful not to scratch the display, handlebars or fittings). Shift into the heaviest gear, deactivate the clutch (Shimano) or lock the rear derailleur in the extended position (Sram). Remove the thru axle and then remove the rear wheel.
Loosen the old cassette. To do this, insert the cassette tool into the lock nut and loosen it anti-clockwise while holding it with the chain whip. The larger the sprocket on which the chain whip rests, the better the leverage! Once the nut has been loosened, it can usually be unscrewed by hand.
The cassette can now be removed from the freewheel. The first sprockets are often not firmly attached to the rest of the cassette and should not be lost, nor should the spacer rings between the sprockets. If the cassette is firmly seated, it has usually seized into the freehub body and can be released with careful levering.
Clean the freewheel. The freewheel must be replaced if it is badly worn, but slight notches are not a problem. Replacing the freewheel is a little more complicated with many wheel manufacturers and is a job for a specialist workshop or experienced mechanics. Exception: Microspline freewheels such as those on DT Swiss hubs. Here, the freewheel can simply be removed.
Mounting: Shimano 11- or 12-speed cassettes with standard HG or Microspline freewheel
Always grease the freewheel to prevent it from cracking, then fit the new cassette. Pay attention to the asymmetrical grooves in the freewheel and align the cassette accordingly. The easiest way is to align the widest groove on the freewheel upwards and position the cassette here. Then push the cassette onto the freewheel as far as it will go and screw in the lockring by hand.
Mounting cassette with Sram XD freewheel
Grease the thread and teeth generously, as grease-free XD freewheels from Sram tend to crack. Then fit the cassette and turn it until it can be pushed onto the grooves. Then screw on the lockring by hand. Note: Some cassettes for XD driver bodies, for example from E-Thirteen, must be fitted in two steps with a separate lockring. Normal Sram cassettes, however, are fitted in one piece.
Tighten the lockring to the specified torque (usually over 30 Newton metres). Then refit the rear wheel.
Converting the chainring ratio on an E-MTB
Fitting a chainring with direct mount
To change the gear ratio on the chainring of your E-MTB, you need a new chainring. The first step is to remove the chain from the chainring. In some cases, it may be necessary to remove the chain guide. However, if you can remove the chain despite the chain guide, you should leave it at that, as some chain guides are fiddly to fit.
Dismantle the crank on the drive side. For some cranks (e.g. Sram), an 8 mm Allen key is sufficient to press the crank off the shaft. For other cranks, you will need a press-out tool suitable for your crank.
The lock nut of the direct mount chainring is now exposed and you can remove it. Unfortunately, this often requires another special tool. Common systems are available from Bosch and Shimano, for example, but some chainrings can also be removed using classic bottom bracket tools. Attention, screwdriver tipThe lockring of the chainring has a left-hand thread, so it is loosened in a clockwise direction. The best way to do this is to apply the tool and prevent the rear wheel from turning by applying the rear brake.
If the chainring is loose, it can be removed and replaced with the new chainring. The mount for the chainring should be cleaned and generously greased afterwards to avoid cracking noises. The tightening torque should also be observed here during assembly. The left-hand crank helps to counterhold the lockring so that it can be tightened accordingly. The right-hand crank can then be refitted and tightened. It goes without saying that the angle between the two cranks must be exactly 180 degrees. In the final step, replace the chain and fit the chain guide.
Fitting a chainring with spider
With the Spider - the chainring is mounted on the arms of the crank with bolts - the assembly for converting the gear ratio is slightly different. First, however, the chain must be removed from the chainring. In some cases, it may be necessary to remove the chain guide. If the chain can be removed despite the chain guide, the guides should remain on the bike because they are often impractical to fit.
Use a suitable Allen key - usually five millimetres - and a second Allen key or a special chainring spanner to loosen the screw connections between the spider and the chainring. Put the bolts safely to one side. Then remove the chainring from the spider and thread it over the crank. The new chainring can then simply be fitted in place of the old chainring. Screwdriver tipNote the direction of rotation. The lettering on the chainrings usually belongs on the outside, the inside is often kept simpler.
Screw on the new chainring and tighten it according to the specified tightening torques. Put the chain back on and, if necessary, return the chain guide to its original position. This is how easy it is to fit a different gear ratio to the chainring.
>> A simple way to make your e-mountainbike more off-road capable is to change the crank length. In the article Short e-bike cranks: tuning for off-road use we explain the conversion and its effect.
>> When converting to a smaller chainring, the gears sometimes have to be readjusted. In Adjusting the MTB gears: In 5 simple steps you will learn all the tips you need to do this quickly.
>> >> For all those who have installed or upgraded a new Sram AXS, we show in Sram AXS: This is how easy it is to set up the electronic gearstick Everything from the first pairing of the components to the firmware update.
Adrian Kaether
Editor
