Im mulling the idea of converting my SS Genesis Day One to an Alfine 11 speed.
Ultimately go to make it a touring bike, its got Topeak panniers/bags, dynamo lights, Shimano Di2 hydraulic brakes I fitted.
What I would like to know is those who run an Alfine Di2, what advantage over a mechanical Alfine is there? How long does the battery last with Alfine motor?
I have several Di2 equipped bikes but these are derailleur bikes.
I could potentially use this bike on mega distance tours, with several days without being able to charge from mains supply. I could use the dynamo to provide top up supply to Di2 battery
Im gearing down the bike with a 32 or 34 chainring to allow for heavy loads and climbing hills. The Alfine 11 has a greater gearing range than the 8, so I wont compromise the top speed too much, should be able to get 25mph top speed at 85rpm.
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I've gone Alfine 11 Di2
I've had a frame built specifically for it so that I can fit it with a Gates Belt drive. However, the bike is unfinished due to several problems.
Problem 1 is you cannot source, for love or money a left brake lever for drop handles without a Di2 switch. Shimano lists it, but I can't find one.
Second problem is that I cannot, for love or money, source a Di2-compatible Gates drive sprocket front and back. It isn't standard Gates drive because Di2 requires a 2mm offset to get the chainline right and clear the drive motor on the hub. I've fitted standard chain and sprockets for now.
My goal is to have Alfine, Di2, drop bars, hydraulic brakes and Gates. This required a custom frame, exotic bits and pieces which exist only on paper and, plenty of cash - more than I wanted to spend when I started the project.
Further, the Di2 Control unit - the Shimano Di2 SC-MT800-C won't wake up when connected. I've sent one back already, thinking it was an out-of-box failure but the second one is also dead. There seems to be an incompatibility with either the battery or the junction box. I've managed to confirm that the shift lever work, the hub motor unit works and the battery works, in another Di2 setup I have. What I cannot test is the control unit and junction box because they're incompatible with the other unit. It is a sad story.
At this stage, I have a beautiful custom frame, great wheels etc. all just sitting on a half-built bike 'cause I can't find a left lever or get the MT800 to wake up.
To answer your questions. The Alfine Di2's advantages over manual? None other than the lack of cables. It is essential the same hub bar one small item. The Di2 Alfine hub is different from the mechanical one in that it doesn't have a return spring. The motor pushes and pulls, where on the mechanical one the cable pulls and the spring pushes back in the other direction. The two cannot be retro-fitted or interchanged.
The battery will last just as long as it lasts on a derailer. It is essentially the same motor, just in a different configuration. On both the derailer and Alfine, the motor works when shifting both up and down.
I can't see how you're going to get the dynamo to charge the Di2 battery. The dynamo produces AC at 6V. The battery wants 5V DC and, requires a special plug and, is chipped to not work with any charger other than Shimano's. Also, the dynamo's wattage will be too low for a charge. A standard Di2 battery gives you more than enough life for a long tour in anyway.