Chainring / bottom bracket - wear

Switching systems

In the course of model development, Stromer has used a wide variety of drive systems, gear ratios and shifting systems. These include Shimano, Sturmey Archer, Pinion, Schlumpf.

Gears

The number of gears in the chain drives ranges from 5 to 27, in some cases with a triple chainring at the front and a 9-speed cassette at the rear.

With Pinion, these are the C-Line gearboxes C 1.6 / C 1.9 / C 1.12. with corresponding 6/9/12 gears.

The Sturmey Archer has 5 gears.

The Schlumpf 'Speed Drive' transmission with Shimano XT-9 cassette on the ST1t / ST1s (2016/2017) offers a doubling from 9 to 18 gears.

Chainring wear

Wear in the chain drivetrain mainly affects the chain and sprockets. The long gears are particularly affected. They are generally used the most.

While at least the smallest sprocket (if individually possible) should also be replaced when replacing the chain, the situation is not quite as clear with the chainring. The frequently used combination of 52T chainring and 11-42T cassette (ST1 2019 & ST1 LCI / ST3 / ST5 / ST5 / ST5 ABS) is fitted with a chainring from Gossamer Gear with narrow/wide teeth.

A visual inspection will determine whether a replacement is necessary. Here is a comparison of old / new.

Bottom bracket / bottom bracket axle wear

Here are a few more pictures showing a replacement of the bottom bracket (often referred to as the bottom bracket) and the bottom bracket axle.

While the bottom bracket, chain guard and chainring are available separately on the Stromer models mentioned above, the bottom bracket axle is not. Only the entire crankset can be replaced.

Removal / installation

Crank handle: How to remove and refit the crank arm on the left here.

Bottom bracket: Special tools are required to remove the bottom bracket. This depends on the crankset or bottom bracket used.

The Stromer models mentioned above are fitted with an FSA bottom bracket.

The FSA MegaExo BB-7100 Bottom bracket shells have the tightening torque, the installation side in the direction of travel (R / L) and the tightening direction (arrow) printed on them during assembly.

If you want to loosen the shells, turn in the opposite direction to the arrow!

During assembly, the order of the components is as follows: from left to right.

Left: ┘Crank arm left - shaft washer - bearing shell left
-Bottom bracket shell -
Right: Spacer 2 mm - Bearing shell right

The axle (with chainring/crank arm┌) and the 2mm aluminum spacer ring previously pushed on are inserted from the right.

The torque must also be taken into account when tightening. It is usually around 40 Nm.

A possible alternative to FSA is a Shimano Saint SM-BB80 (housing width=83mm)