Why was the SRAM 8-speed gearing on the woom ORIGINAL 4 replaced with the microSHIFT 7-speed gearing?
The SRAM 8-speed gearing didn't fit perfectly with the frame design of our woom ORIGINAL 4 bikes and the tilted positioning of the chain in eighth gear led to the chain coming off repeatedly on some bikes. In 2021, we decided to switch to 7-speed gearing on the woom ORIGINAL 4 to avoid this problem altogether. Due to supply issues caused by the coronavirus pandemic, our previous supplier (SRAM) was unfortunately unable to provide us with a suitable alternative. Having looked at the 7-speed gearing options on the market, we went with the corresponding microSHIFT gearing because it was the best fit with the design of the woom ORIGINAL 4. We were satisfied with all the tests, quality checks and test rides, which convinced us that the microSHIFT gearing with the twist shifter was a suitable solution we could rely on. Our decision was finally made and we onboarded microSHIFT as a supplier.
One difference between SRAM and microSHIFT is that there is a slightly different actuation ratio between the gear cable and derailleur. The SRAM actuation ratio is 1:1, while the microSHIFT actuation ratio is 1:1.7. This means that when your child moves the gear cable by a millimetre using the twist shifter, the derailleur moves 1 millimetre with a SRAM system and 1.7 millimetres with a microSHIFT system. In other words, the microSHIFT derailleur has greater leverage and changing gears requires slightly more effort with a microSHIFT system than with an SRAM system. As it stands in June 2022, we've started working with our supplier microSHIFT to check all the parameters of the microSHIFT gearing we can change, with the aim of optimising them to make the gears as easy as possible for children to change despite the leverage being greater.
If your child is finding the microSHIFT gears on their woom bike too stiff, please refer to our handy overview of all the potential causes of gear issues and our recommended solutions in this FAQ.