I have just recently found this forum again and read lots of comments - there is certainly lots of cyclist knowledge on this forum. I have a Koga bike with 14 hub gears and a belt drive, which I used in 2015 to cycle from Budapest to home - about 1450 miles. I now have painful knees (age 68) and am looking to buy an electric bike or to convert my bike. I have been doing quite a bit of research but need help on various issues so will start a few discussions - I hope that the forum does not mind.

 

I have looked at the Cyclotricity conversion kit

https://www.cyclotricity.com/uk/custom/mix-match-your-own-conversion-kit.html

 

It looks to be very good, and I would probably buy the best battery. However I have been told that the PAS will not fit on my bike as it does not have a square taper type bottom bracket. If my Koga bike was a normal bike then I could probably change the bottom bracket but the Koga bike has a belt drive so I doubt that I could. Cyclotricity have said that I could get a PAS from another company but do not know of one. I have attacked a photograph of the bottom bracket.

 

I have two other bikes that don't have square taper bottom brackets.

 

Can anyone give me advice?

 

Thankyou

I have 3 bikes with that type of BB, they are GXP or Hollowtech. Most pas magnet discs can be modified to fit and work with a sensor and many of us have done it with successful results.

Thanks for your answer - I will check it out

If you take the LH crank off and take a photo of the BB in the axial direction, we could probably give you a more definitive answer. There's two removable spacers on that side, which can be removed to make room for a sensor.

The LH bearing has two 2.5 or 3mm spacers, can probably remove them and screw the bearing cup up tighter using the sensor ring as 1mm spacer, leaving room for a pas disc between said bearing and crank arm. Disc then only needs the centre expanded to 23/24 dia hole neatly drilled out for tight fit on the cranks through axle, should work fine as long as the disc isn't pinched up tight against the bearing face.

Edited March 5, 20188 yr by Nealh

The LH bearing has two 2.5 or 3mm spacers, can probably remove them and screw the bearing cup up tighter using the sensor ring as 1mm spacer, leaving room for a pas disc between said bearing and crank arm. Disc then only needs the centre expanded to 23/24 dia hole neatly drilled out for tight fit on the cranks through axle, should work fine as long as the disc isn't pinched up tight against the bearing face.

It's not a Shimano hollowtech crank. We need to see what it is before we can say how to fit the PAS unless you recognise what that BB is.

I have uploaded 3 images of the Koga BB - I just unscrewed one bolt and the crank came off. It looks like the PAS could be fitted then the crank screwed tight. What do you think? Thanks for your help

The other issue is that the bike has hydraulic disc brakes. Part of the disc mechanism goes very close to the spokes. However it is 6cm away from the centre of the wheel. Would the new Cyclotricity wheel fit? Does it allow for disc brakes?

Unusual BB set up though not common looks like a Truvative Howitzer type that uses ext bearings with ISIS through cranks for DH bikes.

Isis afaik is 21mm dia, ideally if the Isis shape is marked on the disc it could be carefully dremmeled out to prevent it spinning on the shaft.

You don't have to fit a PAS, although not strictly legal, Cyclotricity will sell you a throttle only system. That's what I did and I'm perfectly happy with it.

You don't have to fit a PAS, although not strictly legal, Cyclotricity will sell you a throttle only system. That's what I did and I'm perfectly happy with it.

That's what I did for my first kit as there was absolutely no way I could fit a PAS.

I was quite happy with it as throttle only as I only needed help on the hilly bits.

I didn't at that time realise it was illegal as Cyclotricity didn't explain this to me at the time. The 21ish mph it gave me was also illegal.

I've since put the kit on a different bike and added PAS, also replaced the battery so now only the front wheel motor is original but still going strong.

Dave.

With throttle you are stuck with fast and full amps which will take it's toll on the battery sooner, with 5 levels of pas you will have more control over power delivery.

1 is next to useless for my needs but if you had young kids or a wife like mine that doesn't like going fast then it is ideal for riding with them.

Throttle is handy as a get me out of trouble scenario such as a broken pas or if a crank arm or pedal fails which is what happened to me once.

With throttle you are stuck with fast and full amps

Mine wasn't like that, lots of variation in power or maybe when you use it all the time you get a feel for it.

Dave.

I have been watching Youtubes so I could understand BB more. I think my type is a Truvative Howitzer type and I can't see how I could het a PAS disc to fit. However the PAS disc could be superglued to the inside of the belt crank but I would need to put a hole 5cm wide in the PAS disc. Is that possible? I have seen PAS discs that are 3 inches in diameter. What is a PAS disc made from? Are there wider PAS discs?

The Howitzer uses a 21mm dia isis spline, so if you could mark the shape on to the disc you could carefully dremmel out the center shape on the nylon/plastic disc. The disc cut out only needs two or three of the spline cut outs to locate on the shaft to stop any disc slip.

Unusual BB set up though not common looks like a Truvative Howitzer type that uses ext bearings with ISIS through cranks for DH bikes.

Isis afaik is 21mm dia, ideally if the Isis shape is marked on the disc it could be carefully dremmeled out to prevent it spinning on the shaft.

That won't work. When you remove the spacers to make room for the magnet disc, the bearing and seal will be further inboard, which will expose the round part of the BB. All he needs to do is drill a 21mm hole in the disc and clamp it between the bearing and the crank, which will happen when the crank bolt is tightened. he might have to thin down the disc a bit in the middle to make enough room for the crank to go on far enough. there's normally a slight boss on each side that can be filed off to save about 2mm on its thickness.

It is possible the isis flutes are a bit longer on the shaft and go inside the bearing a little more we won't know for sure until Mike undoes the bearing.

It is possible the isis flutes are a bit longer on the shaft and go inside the bearing a little more we won't know for sure until Mike undoes the bearing.

No, otherwise it would let water in.

Mine wasn't like that, lots of variation in power or maybe when you use it all the time you get a feel for it.

Dave.

Neither are all 3 throttles on my bikes either! I just squeeze very gently with my thumb on the fixed part and the fingers on the rotating part at hold just where I won't. Just like with scooters and motorcycles long ago!