Help with AFT build

[millzy555]

Hi guys, i recently purchased a secondhand hand AFT kit installed on a bike. Just sorting out the bugs in regards to chainline. My problem seems to be in the higher gears the crank chain will catch the drive chain (if that makes sense). Is it due to the derailleur being out or the motor not aligned?? I will try get a video. Here are some pics to show minimal clearance.



Videos here:

https://youtu.be/tkGCAgWt5_I

https://youtu.be/fdK-xRhJLnM

 

[Lurkin]

I think I can see what you mean. As you shift into the higher gears (smaller cassette cogs) the angle of the chainline changes and the chain to the rear of the bike is catching on the chain for the actual drive itself.

If I've understood this right, it would mean the unit needs to be spaced out from the frame rather than being a derailluer issue. Simple to check if you can take the chain to the drive off temporarily and do exactly what you have done already. Chances are, there is enough clearance and it will not skip as the two chains will not ride up on one another. if this is easy to do (undo tensioner and remove chain) its probably the easiest, cheapest test.

If that's the case, then you need a spacer (somehow, havent seen whats underneath the chainrings) between the chainrings and the BB to push the chainrings out and make the chainring (with the chain to the cassette) more centrally located relative to the rear cassette.

*could be completely leading you astray given I haven't played with one of these yet. :lol:

 

[millzy555]

could be right with a spacer on the 40t drive sprocket. not alot of room to play with there. Not sure if spacing the motor out will give me any more clearance. It seems to lie with the BB

 

[Lurkin]

when its in the highest gear, how much of an angle is there on the chainline?

 

[millzy555]

 

[DanGT86]

In your first pic from the top down it definitely looks like the large driven sprocket on the freewheeling crank is too far inboard. If you look really close at the picture the chain looks straight where it is in contact with the outer chain-ring then it goes crooked to reach the small sprocket on the aft drive.

Is there a spacer/washer between the freewheel and the crank arm? It looks like there is an extra black thing in there that isnt the crank arm or the freewheel. If so, that might need to go on the other side of the freewheel.

Can you remove the large chainring and move it to other side of the freewheel flange? Might have just been installed on the wrong side.

Also, check to see if the bottom bracket is supposed to have a spacer between the frame and the threaded bearing cup. On my bike the bottom bracket has a spacer that goes on the drive side. If that was installed on the non drive side or was missing it would put everything too far inboard possibly causing the issue.

 

[millzy555]

ok will address all these. Seller just told me then that the 4 higher gears cannot be used due to chains crossing over

 

[millzy555]

In your first pic from the top down it definitely looks like the large driven sprocket on the freewheeling crank is too far inboard. If you look really close at the picture the chain looks straight where it is in contact with the outer chain-ring then it goes crooked to reach the small sprocket on the aft drive.

Is there a spacer/washer between the freewheel and the crank arm? It looks like there is an extra black thing in there that isnt the crank arm or the freewheel. If so, that might need to go on the other side of the freewheel.

Can you remove the large chainring and move it to other side of the freewheel flange? Might have just been installed on the wrong side.

Also, check to see if the bottom bracket is supposed to have a spacer between the frame and the threaded bearing cup. On my bike the bottom bracket has a spacer that goes on the drive side. If that was installed on the non drive side or was missing it would put everything too far inboard possibly causing the issue.

Yes you are right. The outer chain ring definitely needs to come out more (unsure how). From what i can see there maybe a spacer (0.5mm nuts i can see in between the two chain rings). Setup is running 40T main and 30t which isnt stock. confirmed this with Jim at AFT. Dont know if this would cause the issues im having

 

[Nathan]

From that photo it looks like the motor chain is a lot wider then the bike chain? if so thats unusual as i think they normally have the same 3/32 width wipperman chain on the AFT kits same as the bike whereas that looks wider ?

Also from that photo its hard to tell the angle but it seems the chainwheels should sit a bit further out to align with the motor sprocket and that may also fix the other gear issue at the back? Maybe you missed installing a Bottom bracket spacer on the crank side? as this will move it all over that way by 1mm or so.

 

[millzy555]

Yeah the motor chain is heaps wider!, looks like a half link chain.

Here are a few more pics





Moved it slightly over. Should there be nylon chain runners??