I am curious about an electric assist for my Q559 and liked the look of the @Romagjack setup, but have a few considerations to chew on…
I only really want assist on ugly hills and inclined starts, so I am looking at the smallest option I can get.
It is important to me that there is negligible or no resistance when the motor isn’t in use.
How long do you think you would like to ride this bike?
If you are thinking of a year, then do anything, and then kiss your investment goodbye. If you have a longer time horizon, you might spend your time and money on choices that will serve that. Do you hope to ride the bike longer than 3 years?
Any geared motor will wear out it's gears, and you will need to stock replacements for later. A well designed direct drive motor should only require eventual replacement of the bearings - generally just two main ones.
If you use a large fraction of the capacity of a lithium battery in regular use, then it's good for about a year - plan on paying for a new one each year. The battery is generally equal to or exceeds the price of the second most expensive part - the motor. What does replacing a battery yearly do to your budget? In addition to an unavoidable expense, this leaves you at risk of rises in battery prices and the possibility they may not be available when you are forced to replace one.
Research lithium battery longevity and you will find that charging to 100% and using most of that routinely kills batteries very quickly. Thus, multiply the cost of the battery you choose by the number of years you wish to ride the bike because for that use profile, you will be replacing the battery yearly. My own real-world experience matches this.
Charge a lithium battery to 80-85% and size it so as to use less than, say, 50% in routine use means the battery is likely to last for 5 years or more. How does that change your financial calculations?
"no resistance" is more of a boogie-man than a reality. Grin has the data to show that 'electronic freewheeling' uses less battery than a physical freewheel when the motor also does regen. It uses less, and there is no drive wear, and also your brake pads will not wear as you won't need them to slow or stop the bike. A small power draw from the battery overcomes the magnets and the wheel turns like there is no resistance at all, and the power used is less than the power returned from regeneration -
in ordinary riding.
My brakes are deliberately loose so that the switches close before there is any physical engagement and my bike is slowed and stopped by the motor. When the switches close, the controller treats the throttle as a brake pedal (in addition to a pre-settable braking input) and I can vary the braking. I can also bring the bike to a halt. No issues with wet or dirty brakes, and only rarely do I apply the physical brakes - and when I do, I find the pads are not worn, as they haven't been generally used. They grab fully in an emergency stop, and I can modulate the braking with just the motor throttle for downhils with no concern about heat.
Do you think the bike might be useful long enough that your changing health will matter?
Exercise helps but does not prevent changes after 60. In investigating the issues I have with my back, I came across a comment from an Orthopedic surgeon mentioning that while the support between vertebrae is like toothpaste for younger people, after 60 it has "the consistency of crab meat". No one exercises their way out of aging - even though it certainly does ease the path (and provides enjoyment in other ways).
I am taking a long term view of riding my bike. My back (and my physiotherapist) says it must be a recumbent. The unavoidable physics of Lithium batteries say I must use one large enough that I only use a fraction of it's full capacity - but I'm rewarded by having it for the life of several smaller batteries. No gears in my motor says I don't worry about wear and repairs later (I accept there are good cases for this, however). Regeneration says I don't wear out brakes.
Having a motor says I don't fear wind or hills so I ride more - very important as my body ages. And I can continue to go nice places - it's a magic carpet.
How long do you want your investment to serve you? A clapped-out battery has no resale value to recover.
