18-Speed Bike Any Good For A Motor?

  • Thread starter Deleted member 35369
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Deleted member 35369

Hey guys, I have an 18-speed bike that I am going to chuck a stock BT100 motor onto, and I just want to know if I should leave the gears or convert it to single-speed. Thanks in advance.
You want drop outs that allow you to adjust chain tension by moving the wheel fore and aft and also rim or disc brakes. Coaster brakes can be made safer but it requires a complete overhaul and upgrade.

Room for the engine is also very important unless you go with friction drive which is much easier to set up.


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Completely ignored the actual post. Oof, sorry.

This will be very technical: If you go single speed you will need a way to tension the chain whether that be a device made to replace the derailleur and act as tension alone or jist using the old derailleur with the limit screws set so it can only be on the single cog. Or even just moving the wheel fore and aft in horizontal drop outs.

Easiest way to get your multispeed down to one is take the extra chainrings off the front (be it a 2x9 or 3x6) and leave the rear in the cog you like the best. Don't need to run any cables to the back just play with the limit screws.

I think ditching the front derailleur does makes sense here, leave more room for the engine but pictures will help immensely.

If your bike has a thread on freewheel you can just get a single speed freewheel, then re-dish the wheel to get a good chainline or if its a freehub with a cassette you can get spacers and only leave one on.
I'm going to make the assumption you're referring to a 3x6 department store mountian bike/hybrid and not a 2×9 road bike. With the 3×6 department store bicycle you'll need to replace the rear stock axle with a cro-molly axle.

Leave the 3×6 in place. In the event you need to provide any pedal assist you'll have more ratios to select from. Here's how a 3×6 is shifted:
1(1-4); 2(2-5); 3(4-6) for 11 non-redundant sequential ratios.

When it comes to pedal only power on multi-geared bikes; if a gear is too hard or too easy to comfortably maintain a cadence (crank rpm) of 70-90 it means you're in the wrong gear. This is where a bicycle computer with a cadence meter on it comes in handy. Take-off gears are 1(1) for going up hill; all other Take-offs use 2(2).
My other bike is 2*8. super low low. I can walk faster. Not high enough to offer resistance a higher speeds, so I'm free wheel peddling. Took a bit to get used to. I try to maintain the illusion of motor assist.

This one has 3* 8 should be much higher geared. Still in the works. Had to make a hanger for the rim brake just too far from the wheel even with long reach calibers. 27.5 wheels and 48 sprocket.

Lots of room for everything.


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