Electronic Drivetrain: Is it worth the hype?

[Stefan Mikes]

Current mechanical system

I keep a mechanical Shimano Deore XT 11-speed drivetrain on my Vado 6.0 and have no intention to replace it. (I will only discuss 1x drivetrain for flat handlebars here).

Pros

• Mechanical drivetrains have reached their technological paramount since the invention of the first modern derailleur by Tullio Campagnolo in 1949
• Extremely long life of the derailleur and shifter
• Works flawlessly and precisely in any weather
• Does not need any intervention on a ride (such as battery charging)
• Shimano high-end shifters allow multiple gear downshift and also pulling the upshift lever in addition to pushing it.

Cons

• Require adjusting by the barrel adjuster to fix the indexing as the cable core stretches
• The derailleur cable (or its core) needs to be replaced once in a few years
• The shifting is rather slow
• You cannot shift for the whole cassette range in one go
• Your thumb might hurt after a day's ride

Electronic drivetrains

I gave in to the hype and tried to equip my sporty Vado SL with an electronic drivetrain. I absolutely didn't need to do it. The conversion only freed up the inner of the frame for fitting yet another mechanical cable, possibly for the mechanically actuated dropper seat post. So the saga began, and it came with a buyer's remorse repeatedly.

Electronic wireless drivetrain pros and cons

Pros

• One cable less
• No need to adjust the drivetrain, and if it is needed (e.g., a derailleur hanger bent on a ride), the adjustment is very simple and can be done in an app (or by the shifter "adjustment mode")
• The shifting is very fast and the shifting speed can be further enhanced at the cost of the derailleur battery life
• The shifting is crisp and precise
• You can shift for the whole cassette range with a single shifter button push, or limit the shifting to 2 or 3 gears at a time
• Your Gear Number can be displayed on a bike computer (such as Garmin or Wahoo). Also, the battery levels.
• Additional features such as Auto Shift are available for specific e-drivetrains and compatible e-bikes
• Your thumb will certainly hurt less

Cons

• Extortion prices
• Need to recharge the derailleur battery from time to time, and occasionally replace the coin batteries in the shifter
• Electronic drivetrains can -- reportedly -- fail under frosty weather conditions
• In case either battery is flat, you are stuck in the current gear
• As any electronic device, the derailleur or the shifter can break, leaving you with no bike.

Electronic totally wireless shifter and derailleur: Options

Historically, it all started with Shimano Di2 in 2009. The Di2 was a wired system, where the mechanical cables were replaced with electric wires, and the battery resided inside the seat-tube. As SRAM came with a totally wireless Eagle AXS drivetrain and integrated derailleur battery, it took Shimano long five years to develop a competitive system. Meanwhile, the Chinese were working, too...

• Wheeltop: Works with any 3-14 speed cassette. Integrated (irremovable) battery. Excellent shifter.
• SRAM AXS comes in two flavours:
  • The one for T-Type (Transmission) SRAM drivetrain and Universal Derailleur Hanger (UDH)
  • Another for any derailleur hanger (Upgrade Kit)
  • The number of gears (speed) is fixed, and it can be either 12 or 13 speed
  • Only good for SRAM cassettes.
• Shimano Di2 MTB wireless comes in several versions:
  • -250 is for any 12-speed bicycle. -260 is for Shimano and newer Bosch e-bikes, and it is partly wired to the e-bike system
  • 9- is for XTR, 8- for XT, 6- is for Deore
  • All these systems are mutually compatible
  • Only good for 12s Shimano cassettes.

CAVEAT EMPTOR: Once you have upgraded from the mechanical to the electronic system and you had removed the shifter cable, it is very hard to return to the mechanical (at least mentally). Consider whether you really need the electronics!

 

[Stefan Mikes]

Wheeltop EDS OX 2.0

An electronic derailleur and shifter made for any 3-14 speed cassette. Its 93 mm version is long cage, and it is good for up to 10-51T cassettes.

Cost and setup
The kit cost is €400. The kit contains anything you might need: the derailleur, the shifter, the magnetic charging cable (Micro USD with a USB-C adapter) and a sheet with a QR code to download the Wheeltop smartphone app. The app is “illegal” (outside of the official stores) so you need to allow your smartphone even downloading and then installing it. You need to register yourself in the app before you do anything else.

You start with attaching the magnetic plug to a clearly marked socket on the derailleur, which wakes the device up. Then you pair both the derailleur and the shifter with the Wheeltop app.

Installing the derailleur is very easy. After you have removed the old system, just screw the main derailleur bolt into the derailleur hanger.

Before you do anything else…

Start the app, and go to the settings, specifically to the “Change cassette” item. Choose the proper number of speeds for your cassette. Then you can install the chain.

Important: The tension pulley (the bottom one) is Narrow-Wide. Please pay attention to install the chain the way it “sits” on the proper pulley teeth!

Critical
The OX2.0 can only be adjusted when the H limit screw has been used to align the chain for Gear 1 (the smallest cassette sprocket). There is a very clearly marked place to start the work. You will need a 2 or 2.5 mm (I think) Allen key to remove the screw holding the housing in place. Remove the housing. Identify the H screw. Using an Allen key, perfectly align the chain with the smallest cassette sprocket. Do not close the housing yet as you might apply the L limit screw later as well. If you miss this step, the derailleur adjustment will be virtually impossible.

The gear adjustment
While it is the best to just hang the bike on a work stand, I did all adjustments by setting my e-bike on a kickstand, leaning the bike to the left, and raising the rear wheel that way.

The derailleur is set for the Shimano cassette sprocket spacing. However – and it is unique for Wheeltop – you can adjust the derailleur electronically for any gear individually. There is an Adjustment section in the app. First, rotate the crank to determine whether the chain moves smoothly in the Gear 1 (the smallest cog). Then, graphical arrows in the app allow you shifting into each lower gear. There, you can adjust the alignment using arbitrary “units”. Your task is to make sure the chain moves smoothly on each gear.

This procedure is mandatory for SRAM cassettes, which have a slightly different sprocket spacing to the Shimano one.

Once all the gears have been adjusted, work delicately with the L screw to prevent the chain skipping towards the spokes. (I suggest overdoing it. Work with the L screw as much as the chain cannot jump onto the largest sprocket. Easy up on the L screw until you can downshift into the lowest gear and everything works smoothly). Now, close the cassette housing.

Eventually, locate the B-screw. Work with it until the guide pulley (the top one) teeth are 8 mm apart from the largest sprocket teeth (you can check it with an 8 mm Allen key as a measuring tool).

(Of course, you will need to install the shifter on the handlebar, too).

A known fault
Sometimes, the derailleur “thinks” some gear (for instance Gear 5) is Gear 1. There is a procedure to re-learn the derailleur where the Gear 1 is using the app.

Ways of waking up the derailleur
Any stronger shake of the bike or the rotation of the rear wheel triggers the accelerometer and instantly wakes the derailleur. Also, charging the battery (which is done on the derailleur) will wake the device up.

Experience

I was absolutely bought by the Wheeltop system once I understood how it really worked. I was especially delighted with the shifter. It is big, with two distinct buttons (the top one is intentionally recessed) and with different patterns on each button.

You can “reverse” the gears in the App, so the largest sprocket becomes Gear 1. The current gear is reported in Garmin or Wahoo always starting from the largest sprocket as 1.

The Lemon
The Wheeltop drivetrain served me for exactly for 3 weeks. As I upgraded the freehub body/cassette to 12-speed and used the “Change cassette” option in the app, the derailleur moved the chain to Gear 5 and… died. No shaking, no charging would wake up the device again! Moreover, it has disappeared from detectable Bluetooth device list.

The technical support and warranty
So far, the most disappointing. Wheeltop respond once or twice a week and behave like kids that understand nothing. They requested sending me a video, which I did, and no response since.

 

[Stefan Mikes]

Shimano Di2 9250 with an -R switch clamp

It is not enough to buy a Shimano e-derailleur. You need an Upgrade Kit that includes:

• The derailleur
• The shifter (-IR for Shimano I-Spec brake levers or -R with a handlebar clamp)
• The derailleur battery
• The charging bracket with an USB-C cable
• A spare 12-speed Quick Link

Shimano delivers 6 distinct Upgrade Kits: 6250, 8250 or 9250 for regular bikes and e-bikes (totally wireless) or 6260, 8260 or 9260 for Shimano and Bosch Smart System e-bikes (with a wire to connect the derailleur to the e-bike system for powering and control).

The least expensive M6250-R Upgrade Kit is €442 and the M9250-R SGS (long cage, clamp shifter), Upgrade Kit is €690. These prices include Euro tax but exclude the shipment cost.

Setup
I already had a Shimano CS-M8200 12 speed, 10-51T cassette on my rear wheel, and no mechanical drivetrain parts. I started with charging the battery in the provided charging bracket, then installing the E-TUBE Project Shimano app, registering myself etc.

Installing the derailleur was very easy: just bolting the derailleur to the hanger and installing the chain. Note: No Narrow-Wide on any pulley. Easy.

Installing the battery
Easy peasy. It is easy to remove the housing, insert the battery and replace the housing.

Pairing the derailleur, shifter, and the app
Although it all can be done on the devices, I went the app way. There is a tiny button on the derailleur. You depress it as long as there is a blue LED flashing next to the button. The App will pair the derailleur. Next, you pair the switch (it is the shifter for you) by scanning the QR code of the switch housing.

The switch/shifter will not work until you Disconnect the derailleur in the App.

Adjustment
The H, L and B screws are easily accessible. I would start myself with setting the H limit screw first. However, Shimano suggests switching to Gear 5 first… …but if your derailleur hanger is bent even a little, it is impossible Note: At this moment, you can only switch gears using the E-TUBE Project app!

The digital adjustment can be done for -18 to +18 arbitrary units globally for the entire cassette (the system relies on the manufacturing precision of Shimano). So, if you can shift to Gear 5, your task is to adjust the derailleur the way the chain runs smoothly in that very gear. Then you need to switch to the smallest sprocket (still using the App), adjust the H-limit screw, then downshift to the largest sprocket (still using the App!), adjust the L-limit and B screws. Eventually, you must disconnect the derailleur in the app.

In case you cannot switch to Gear 5, remain in the smallest sprocket. Use the H limit screw to align the chain with that sprocket. Then apply the global adjustment in the App until you are able to downshift. Eventually, work on L limit and B screws in the largest sprocket.

Extra options
Using the app, you can change the behaviour of the shifter. For instance, you can swap the paddles. Or you can assign D-FLY Mode 2 to the third shifter button to swap the data pages on Garmin or Wahoo.

You can also allow shifting across the entire cassette range or limit it to 2 or 3 gears at a time (for deep shifter paddle pressing)

Ways of waking up the derailleur
Unfortunately, Shimano is very conservative to conserve the battery charge. To have the derailleur activated, you need to give the rear wheel a real spin, and you must switch a gear using the shifter. It is not immediate! (I guess pushing the derailleur button once would wake the device up)

Experience
The top-end Shimano e-derailleur per se is very good. Combined with an expensive 12-speed cassette it is precise, crisp and fast shifting. I, however, dislike three facts:

• The derailleur wake up takes too long after the pedalling start
• The derailleur data take ages to appear on my Wahoo after the ride start
• I am not happy with the switch-shifter at all!

The shifter has two short paddles. These are a way shorter than the comfortable mechanical ones. Moreover, the rear (upshift) paddle can only be pushed but not pulled! I experience issues to reach that paddle in my setup. To compare: Wheeltop shifter buttons are large and easily accessible! Shimano could have done a way better work… Even the SRAM shifter I had a chance to test was a way better than the Shimano!

The Japanese brand took a lot of care that the electronic paddles felt like the mechanical ones. The outcome? My thumb hurts

The Lemon
The top shifter paddle detached and disappeared on the first longer gravel ride. Which tells me a lot about the current Japanese workmanship.

The technical support and warranty
The seller, BIKE24 asked for pictures, which I sent. I was offered a €20 refund and a suggestion to buy a €15 paddle in a specialist German store. I disagreed, so BIKE24 will buy and send me a new paddle in several weeks. Well, I thought I had a 2-year warranty on the shifter…

Please feel free to join the discussion now.