Shimano Alfine gearbox adaptation

[The Great Boffo]

I'm sure most of you are going to hate this, but I'm posting it anyway.

I'm a fan of the Shimano Alfine 11-speed hub. Nice gear range, can shift while stationary, and uses single-speed cogs and chains, which are more durable. What I'm not a fan of is being dependent on an expensive, custom-built wheel to go with it. If it needs re-truing, your bike is out of action for a few days, and if it gets damaged, you have to fork out for another one. But what if there was a way to have the benefits of an internally geared hub, while still using cheaper, interchangeable, off-the-shelf wheels?

There is. As long as you don't mind riding "The bike of Frankenstein."

The idea was simple: to mount the hub to the frame and use it as a gearbox which would then drive the rear wheel with a second chain. Making it actually work required some headscratching, and this version is my second attempt (the first version worked, but had a few issues like chain misalignment and not staying properly located.)

This kid-size BMX frame provided the rear forks to mount the hub. By a fortuitous coincidence, the bearings from an old bottom bracket are a snug fit inside the bearing housing, which made mounting the forks quite easy. An old crankshaft will go through the bearings and the mounting plates attached to the frame.



The rear forks cut from the frame, some gaps filled to keep out water. It needed some gentle persuasion with a hydraulic jack to widen it enough for the hub. Next to it is a suspension component from a previous bicycle (written off in an accident,) that will be crucial to mounting it on the new bike.





This pic shows how the two parts will join together:



Everything looks better after a little paint:




This is the hub, with adaptor plate that lets me mount the output gear:




Overview of the completed project:




Had to grind down the right hand crank arm to get clearance, but there's still plenty left:

[The Great Boffo]

Closeup of the mounting plates that sit underneath the BB bearings. The fork mount is between these, held in place by an old crankshaft.



Last pic shows how the crank drives the hub, which in turn drives the rear wheel after providing the gear change:|



So, mission accomplished. I'm expecting three main responses here:

1: "It's ugly!" Yes, don't care.

2: "It adds weight!" - yes, but not much. The hub itself weighs more than the forks and strut.

3: "You lose efficiency by running two chains!" - undoubtedly true, but I didn't notice any difference on my ride to work, so I still don't care.

While I'm sure half of you are collecting pitchforks and torches, the bottom line is, I built this to meet my own requirements, and I'm happy with the result. Feel free to post your opinions.

[Thoglette]

I built this to meet my own requirements, and I'm happy with the result. Feel free to post your opinions.

Way cool!
Nice to see that it’s turned out as you hoped.

Any chance of a profile shot? I imagine it looks a bit like a hub motor setup?

<mode=silly>Now, on the basis that nothing exceeds like excess, one needs to add a 11 speed hub at the back for -drum roll- 121 gears!
</mode>

[MichaelB]

Gotta admire the effort and getting it to work !!

Well done

[The Great Boffo]

I built this to meet my own requirements, and I'm happy with the result. Feel free to post your opinions.

Way cool!
Nice to see that it’s turned out as you hoped.

Any chance of a profile shot? I imagine it looks a bit like a hub motor setup?

<mode=silly>Now, on the basis that nothing exceeds like excess, one needs to add a 11 speed hub at the back for -drum roll- 121 gears!
</mode>

Lolz to the idea of adding a second hub!

BTW: you could retro-fit a Pinion gearbox the same way - it would actually be easier. But a 12-speed Pinion with shifter etc. runs about $2K USD, whereas the Alfine conversion cost me just over $800 AUD all up.

[baabaa]

I'm sure most of you are going to hate this, but I'm posting it anyway.
Not sure I hate it, but without a front dyno hub powering up a battery which is used to shift gears on a Alfine Di2 is looking a little under-engineering to me.

[robbo mcs]

I like a bit of ingenuity, like a pinion . Get ready for people to ask you about your e-bike

[The Great Boffo]

I'm sure most of you are going to hate this, but I'm posting it anyway.
Not sure I hate it, but without a front dyno hub powering up a battery which is used to shift gears on a Alfine Di2 is looking a little under-engineering to me.

Lol! I really didn't see any advantage to the electronic shifting. Besides, a dyno hub means a custom-built wheel - the element I wanted to remove.

[The Great Boffo]

I like a bit of ingenuity, like a pinion . Get ready for people to ask you about your e-bike

Yeah, they already have! Which is understandable. I've never seen anyone do this with a hub before. (Yes, someone might have, just saying, I haven't seen it done.)

[bychosis]

Its cool. Sure it's not thw prettiest thing, but looks like it works.

Interested to know what the drive ratio is compared to standard setup. I can see the crank chainring appears to be bigger than the gearbox end and the gearbox end looks quite large too. Have you set up the rear wheel as regular single speed? Does it run a tensioner?

[The Great Boffo]

Its cool. Sure it's not thw prettiest thing, but looks like it works.

Interested to know what the drive ratio is compared to standard setup. I can see the crank chainring appears to be bigger than the gearbox end and the gearbox end looks quite large too. Have you set up the rear wheel as regular single speed? Does it run a tensioner?

Rear wheel is single speed, derailleur functioning as a tensioner. That's essential, because for some reason I don't understand, the crank mount on this bike moves back and forth with the suspension, so the distance changes.

Gear ratios are: Crank 32 T, hub input 20 or 22T, hub output 36T, rear wheel 44T.

[bychosis]

Thanks. I did spot thw derailleur after i posted. It's not unusual for a dual suspension bike chain to change effective length throughout the suspension travel.

How have you adapted two cogs on to the alfine?

TBH this seems the sort of thing that would work ok on the cheapo single speed fat bike I had but sold because single speed just wasn't working for me.

Just using a single cog and spacers on the

[The Great Boffo]

How have you adapted two cogs on to the alfine?


TBH this seems the sort of thing that would work ok on the cheapo single speed fat bike I had but sold because single speed just wasn't working for me.

Just using a single cog and spacers on the

The small cog on the Alfine is the factory one that gets driven by the crank. The larger cog is the output, mounted to the hub by an adaptor plate shown earlier:



If you were going to try this with a fat bike, I would suggest using an 8-speed hub as they can apparently shift under load (the Alfine can't.)

[bychosis]

I really should have read more thoroughly!

Unfortunately my last reply got cut short somehow, I meant to ask wether youre running the single speed wheel with a single speed cog with spacers on a cassette hub, have locked the derailleur to a single cog on a cassette or a dedicated single speed wheel?

[The Great Boffo]

I really should have read more thoroughly!

Unfortunately my last reply got cut short somehow, I meant to ask wether youre running the single speed wheel with a single speed cog with spacers on a cassette hub, have locked the derailleur to a single cog on a cassette or a dedicated single speed wheel?

Single speed cog on a cassette hub with spacers. And a rather ugly adaptor plate made from scrap aluminium I scrounged from work.








And BTW, my bad, it's a 42T rear cog.

[MattyK]

Love a good frankenbike that meets your desires.

However:

What I'm not a fan of is being dependent on an expensive, custom-built wheel to go with it. If it needs re-truing, your bike is out of action for a few days, and if it gets damaged, you have to fork out for another one.

So instead of an expensive custom built* wheel that might** need retruing, you've got a highly complex custom built frame?

*Its going to be less expensive than what you put together

** It shouldn't need retruing because as an internal hub wheel it should be stronger due to better spoke angles than a freehub wheel. and they are built like tanks so the hub shouldn't break unless you do something that would destroy any other bike. But if it ever does, retruing is easy.

Also you still have the fragile rear derailleur hanging off it - that's your real weak spot.

[The Great Boffo]

Love a good frankenbike that meets your desires.

However:

What I'm not a fan of is being dependent on an expensive, custom-built wheel to go with it. If it needs re-truing, your bike is out of action for a few days, and if it gets damaged, you have to fork out for another one.

So instead of an expensive custom built* wheel that might** need retruing, you've got a highly complex custom built frame?

*Its going to be less expensive than what you put together

** It shouldn't need retruing because as an internal hub wheel it should be stronger due to better spoke angles than a freehub wheel. and they are built like tanks so the hub shouldn't break unless you do something that would destroy any other bike. But if it ever does, retruing is easy.

Also you still have the fragile rear derailleur hanging off it - that's your real weak spot.

1: Not a custom built frame, just a mounting added to an existing frame. It's actually pretty simple.

2: No, a custom built wheel is not going to be cheaper. Most of the $800 this cost me was for the hub, shifter, and small parts kit. I only paid $40 for the kid's size BMX, the suspension arms were from a wrecked bike.

3: I originally did have a custom wheel built around the hub. It did need retruing, which is what prompted me to do this instead. And I'm not worried about the hub itself getting damaged, just the wheel.

4: The derailleur is attached by a sacrificial bracket which is cheap and easy to replace should it get broken.

[MichaelB]

I gotta sort of agree with MattyK, but also understand your view.

Re :
1. Yeah, a standard frame to start with, but with a custom add on, so pretty custom ...
2. I'd disagree - a hub laced to a wheel is not that expensive or hard, and probably less effort than what you did, but again, can't argue with your effort
3. Wheels are pretty easy to true and only requires a spoke key and a bit of practice.
4. The setup also requires a very long chain and has an RD that doesn't do anything. Maybe a simple tensioner (like on a SS conversion) would be better ?

[The Great Boffo]

I gotta sort of agree with MattyK, but also understand your view.

Re :
1. Yeah, a standard frame to start with, but with a custom add on, so pretty custom ...
2. I'd disagree - a hub laced to a wheel is not that expensive or hard, and probably less effort than what you did, but again, can't argue with your effort
3. Wheels are pretty easy to true and only requires a spoke key and a bit of practice.
4. The setup also requires a very long chain and has an RD that doesn't do anything. Maybe a simple tensioner (like on a SS conversion) would be better ?

2: Not hard for you maybe, but outside my current skill set. I'm a tradesman not a bike mechanic, so I went with what I'm good at.

3: Last time I tried that it didn't turn out particularly well. I'm sure it's easy when you know what you're doing, but it probably helps to have someone walk you through it the first couple of times.

3: I did use a tensioner originally, but it jammed up and stopped tensioning. I already had a spare derailleur, so I just went with that.