LTWOO eR9: two years with a Chinese electronic groupset

The LTWOO eR9 is an electronic road groupset (2x, configurable for 7- to 13-speed cassettes) at half to two-thirds the price of Shimano Di2. The author's is one of the early versions and has done more than two years. The shifting and the electronics have given me nothing to complain about. The brakes, some of the finish, and the support are another matter.

The eR9 groupset. Photo: L-TWOO

What I liked

The number of sprockets is set in the app. The group can be configured for 7- to 13-speed cassettes, so you can build the bike around the cassette you have rather than the one the group was certified for. Neither Shimano nor SRAM gives you that freedom.

Per-sprocket derailleur adjustment. The app offers fine adjustment for every gear, plus a "half step" for the front derailleur that you trigger from the shifter while riding if the chain rubs the cage. SRAM AXS does not offer this at all.

Ordinary batteries. It runs on standard 14500 lithium-ion cells (plus CR2032 in the shifters), which cost next to nothing on any marketplace. The cells slot into a separate housing: assembled it is a solid stick barely bigger than two 14500 cells. Inside, weight-saving has left it flimsy — taken apart it is a nest of very thin wires, so open it carefully.

USB-C charging. Early versions charged through a magnetic connector; newer ones have USB-C in the front derailleur, so any power bank will do on the road.

Price. This groupset was bought for $400 including delivery; an electronic Shimano group cost around $800 at the time. Prices may have moved since.

Electronics and shifting. Two years, not one failure, not one missed shift. That is the whole point of the exercise.

What I did not like

The brakes: pad self-adjustment. This is the main complaint. On early versions the pads do not advance as they should and the bite point wanders. Bleeding does not fix it: the author bled them three or four times.

What it looks like: video 1 and video 2.

The stock L-TWOO hydraulic caliper

The cure is replacing the calipers: either with Shimano ones (fully compatible) or with ZRACE XG — two-piston, machined from a single piece of aluminium.

About the pistons

The caliper apart, with a titanium piston fitted

The stock LTWOO calipers use ceramic pistons, like Shimano. The ZRACE XG ships with aluminium ones, and that is their weak spot: aluminium conducts heat far too well, and on a long descent that heat goes straight into the fluid. This build uses titanium pistons bought separately: lighter, and much less heat into the fluid. They are sold as a separate part — for example for Shimano's 105/Ultegra/ Dura-Ace road calipers; you pick the size by diameter.

Weight and price. ZRACE quotes 97 g per caliper (one reseller lists ~113 g; no independent weighing has been published). Shimano quotes 120 g front and 110 g rear for the Dura-Ace BR-R9270. So the ZRACE is at worst no heavier than top-end Shimano, and lighter once the pistons are swapped for titanium. Meanwhile it costs about $40 per caliper against $120–200 for Dura-Ace — three to five times less.

Why ceramic is worth leaving behind. Current 12-speed Shimano road calipers use resin pistons; earlier generations and the MTB line use ceramic. A cracked ceramic piston as the cause of total brake failure is documented: one case saw braking lost on a descent, and Shimano's own warranty response named a cracked piston. Yes, these are isolated cases — but Shimano brakes are on so many bikes that there are plenty of them on YouTube, and nobody wants to join that list mid-descent.

The rest

The front derailleur cage. Subjectively it looks plainer than Shimano's. In two years it has given no trouble at all, so treat this as an observation rather than a verdict.

Support. Effectively absent. The author reported the pad-adjustment problem and the AliExpress seller kept suggesting he "bleed it once more", although the messages had said plainly that it had already been bled several times. This is not an isolated case: reviewers note that no clear warranty is stated and that everything goes through the reseller rather than the manufacturer. Buying LTWOO, count on yourself.

Automatic front-derailleur trim

The feature has come full circle. It worked when this groupset was bought, then vanished after one of the updates — forums linked that to patent pressure from Shimano. In June 2026 LTWOO brought it back: the release notes for app version 2.8.6 list the addition of automatic "half-gear" for the front derailleur. The author has not tried the newer versions.

Why LTWOO and not Wheeltop

Wheeltop offers some of the same features. But by reputation and in the author's experience Wheeltop is worse on material quality where it does not matter structurally, breaks more often, and has a noticeably worse app — the last point is one reviewers agree on.

Who it suits

If you want an electronic groupset for sensible money, you service your own bike and you are not counting on warranty support, the LTWOO eR9 is an excellent choice and the shifting will not let you down. If you buy one, budget for new calipers from the start; everything else works as promised.