Following my first mid motor bike conversion I thought I would give some feedback, via a number of posts, which hopefully will be useful to those thinking of doing something similar.
Some motor installation advice as follows:
1. Until the motor position is finalised it is easier to work on the bottom bracket with the bike upside down. If you don’t have a workshop stand contrive some support to keep the bike stable.
2. Strip everything off the BB shell including all the cables and BB cable guides if fitted. Pull out any internally routed cables that exit at the bottom bracket. For hydraulic brakes this will almost certainly involve detaching the rear brake hose from the calliper, draining the fluid and cutting off the olive and barb in order to get the hose out of the down tube*. Only then offer up the motor to the BB to check the fit and see what needs “modification”.
3. Unless you are very fortunate expect to mount and de-mount the motor countless times before finally getting it positioned satisfactorily together with the stabilising bracket that passes through the space in front of the chainstay bridge. Anticipate having your patience tested.
4. Only after mounting the motor consider if it is worth trying to route the rear derailleur cable in the gap between the BB shell and the motor BB axel. I did this but it took ages to determine the line of the cable when properly tensioned and I nearly destroyed the stabiliser mounting bracket by cutting a channel through it (see photo below). I also had to remove the BB cable guide and file it down to a height of about 4mm (you may not even have that much space) replace its mounting screw with a grub screw to maintain its correct position whilst supergluing it to the BB shell. With hindsight I would not have bothered as I expect it to be impossible to replace the derailleur cable in future without removing the motor.
5. Depending on how much play there is available in the rotation of the motor it may be impossible to fit the stabiliser mounting plate that sits above the chainstays without some modifications. I had to grind down the outer faces of the stabiliser mounting bracket to allow it to rotate further (see photo below) otherwise it was not possible to get the mounting bolt in. I still had to cut down an allen key to get it to fit in the space between the bolt head and the seat tube.
6. The manufacturer’s instructions (badly translated obvs) state that the BB motor mounting ring should be tightened with the supplied tool to a torque of 40Nm. The supplied tool of course allows no torque measurement but in layman’s terms I believe 40Nm equates to “full welly”. The supplied tool is only just the right side of adequate and given to detaching itself from the ring just at the point when you are applying “full welly” sending your hand with full force into the nearest projection on the bike. From painful experience I advise placing cushioning (old towels, cushions?) on any and all of those parts your hands are likely to hit and also to wear gloves.
7. Avoid fully torquing any bolts until all components except the pedals have been installed and then do them all at the same time. The “last time” you install the motor is never the last time you install the motor in my experience.
* Note - If, like me, you have had no previous experience of hydraulic brakes, in order to put the hydraulic hose back later on you will need a service kit suitable for your brake type. These range in price from expensive to “you must be f***ing joking” for what is a few pieces of moulded plastic. I bought a “universal” kit on Amazon for about £15 which still required the use of some additional jubilee (how appropriate) clips to hold the plastic tubes onto the inserts without mineral oil going everywhere. Don’t be tempted to think you can replace the oil without removing the calliper from the bike and the pads from the calliper. After my first attempt no single part of the calliper escaped oil free.
Part 4 will cover down tube battery installation.
Some motor installation advice as follows:
1. Until the motor position is finalised it is easier to work on the bottom bracket with the bike upside down. If you don’t have a workshop stand contrive some support to keep the bike stable.
2. Strip everything off the BB shell including all the cables and BB cable guides if fitted. Pull out any internally routed cables that exit at the bottom bracket. For hydraulic brakes this will almost certainly involve detaching the rear brake hose from the calliper, draining the fluid and cutting off the olive and barb in order to get the hose out of the down tube*. Only then offer up the motor to the BB to check the fit and see what needs “modification”.
3. Unless you are very fortunate expect to mount and de-mount the motor countless times before finally getting it positioned satisfactorily together with the stabilising bracket that passes through the space in front of the chainstay bridge. Anticipate having your patience tested.
4. Only after mounting the motor consider if it is worth trying to route the rear derailleur cable in the gap between the BB shell and the motor BB axel. I did this but it took ages to determine the line of the cable when properly tensioned and I nearly destroyed the stabiliser mounting bracket by cutting a channel through it (see photo below). I also had to remove the BB cable guide and file it down to a height of about 4mm (you may not even have that much space) replace its mounting screw with a grub screw to maintain its correct position whilst supergluing it to the BB shell. With hindsight I would not have bothered as I expect it to be impossible to replace the derailleur cable in future without removing the motor.
5. Depending on how much play there is available in the rotation of the motor it may be impossible to fit the stabiliser mounting plate that sits above the chainstays without some modifications. I had to grind down the outer faces of the stabiliser mounting bracket to allow it to rotate further (see photo below) otherwise it was not possible to get the mounting bolt in. I still had to cut down an allen key to get it to fit in the space between the bolt head and the seat tube.
6. The manufacturer’s instructions (badly translated obvs) state that the BB motor mounting ring should be tightened with the supplied tool to a torque of 40Nm. The supplied tool of course allows no torque measurement but in layman’s terms I believe 40Nm equates to “full welly”. The supplied tool is only just the right side of adequate and given to detaching itself from the ring just at the point when you are applying “full welly” sending your hand with full force into the nearest projection on the bike. From painful experience I advise placing cushioning (old towels, cushions?) on any and all of those parts your hands are likely to hit and also to wear gloves.
7. Avoid fully torquing any bolts until all components except the pedals have been installed and then do them all at the same time. The “last time” you install the motor is never the last time you install the motor in my experience.
* Note - If, like me, you have had no previous experience of hydraulic brakes, in order to put the hydraulic hose back later on you will need a service kit suitable for your brake type. These range in price from expensive to “you must be f***ing joking” for what is a few pieces of moulded plastic. I bought a “universal” kit on Amazon for about £15 which still required the use of some additional jubilee (how appropriate) clips to hold the plastic tubes onto the inserts without mineral oil going everywhere. Don’t be tempted to think you can replace the oil without removing the calliper from the bike and the pads from the calliper. After my first attempt no single part of the calliper escaped oil free.
Part 4 will cover down tube battery installation.
