If the Wheel Top EDS OX was the first Chinese electronic derailleur (that I was aware of), the LTWOO eRX was the first electronic derailleur from an established Chinese derailleur manufacturer, and was the first Chinese road electronic derailleur, complete with drop-handlebar levers and the rest. It's a small landmark, but a landmark nonetheless.

It's a tidy object that looks well built and well finished and seems to work plausibly well. When it was released, in 2023, it established a new low-price level for electronic derailleurs. But in the way of all things that are both electronic and Chinese, this was old news by 2024 - when LTWOO launched the even-lower-priced LTWOO eR9 (R8001).

The eRX system works with wireless levers and a main battery unit in the seat tube connected by wires to the front and rear derailleurs.

I am a little unclear about the precise history of of the eRX. Some history might be:

• In 2023, the first versions that I saw (being demonstrated at trade shows) were gloss black with glamorous gold graphics (a bit like my LTWOO RX (R5012 M C). I think that this version possibly had the model number R9001.
• In 2024 the p-knuckle and outer parallelogram plate changed colour to 'Technology Blue' and the graphics became silvery in a polychromatic kind of way. This version is possibly referred to as 'v2'; or 'v2.0'. It is also possible that the model number was changed to R9101.
• In 2025 people started referring to the 'v3' or 'v3.0', which I take to imply that the electronics had been updated in some way. Inexplicably, I think that the model number may still be R9101.

All these changes took place over a period of relatively few months - so they are difficult to disentangle.

This example is an R9101 and enjoys the benefits of 'Technology Blue' elements. Whether it is v2.0 or v3.0 is unclear to me.

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• Derailleur brands: LTWOO
• Country: China
• Date of introduction: 2024?
• Date of this example: 2024?
• Model no.: R9101
• Weight: 284g
• Maximum cog: 32 teeth (Source: LTWOO)
• Total capacity: unknown
• Pulley centre to centre: 93mm
• Index compatibility: 10-12 speed
• Chain width: 3/32”
• Logic: top normal as much as it is anything
• B pivot: unsprung
• P pivot: sprung
• Materials: mainly aluminium with a composite p-knuckle and outer pulley cage plate

Ref. 2228