You will often come across the strong and reliable Bosch range of Mid drive motors in its various latest (Generations 3+4) iterations, and now also the highly integrated smart-system . The basic ‘Active Line’ offers modest power (40Nm) for general duties and leisure in flatter areas, the Active Line Plus a bit more oomph (50Nm) for heavier/hillier utility use, and the Performance Line, Performance Line CX and finally Cargo line (75Nm and 85 Nm respectively) for heavy duty use/super relaxed riding in and around Sheffield.
The new lightweight performance-line-sx system has been developed for lighter bikes.
Do be aware that these Bosch motors all have different starting off characteristics (What Bosch call their ‘start up behaviour’ from a standstill). For example Bosch describe the basic Active Line’s starting characteristics as ‘Harmonius’ which in practice means very gentle, and this can be an issue when trying to set off on a hill, particularly if you are loaded.
The two strongest Bosch Performance Line motors (Performance Line and Performance Line CX) and the Cargo line motor offer two distinct advantages over the less powerful Active and Active Line Plus variants for utility users in hilly Sheffield, or indeed out in such as the Peak district
The Cargo line is programmed to offer you mucho assistance as you set off with heavy loads, and the Performance Line and CX motors also help you set off easily with their ‘Sporty’ start up algorithm (but still retaining full and nuanced control)
This strong start can make all the difference e.g.if you are trying to set off uphill from an ASL at traffic lights when loaded.
The clever variable support level algorithms embedded in the ‘Sport’ and ‘Tour’ assistance settings of the more powerful motors are very useful too, these algorithms automatically supply variable assistance levels depending on your pedal pressure, from the ‘Tour’ level right up to the ‘Turbo’ level.
In practice this means that you can leave it in this setting and either pootle along with just light pedal pressures, or, if circumstances or the mood takes you, pedal harder and be given full power for the manoeuvre in hand (or hill, headwind etc)
So less distraction choosing levels, and easier and safer start offs.
The author likes this Tour+ mode a lot, as it provides enough assistance to make life comfortable, but still requires me to put in enough effort to feel like I’m getting ‘the benefit’ of cycling, whilst being reasonably economical of battery power.
Shimano offer similarly rated efficient motors and algorithms – currently for urban/tour use the e5000 (40Nm), e6000 (50Nm) and e61000 (60Nm), and for MTB’s the e7000 (60Nm) and e8000 (85Nm).
The author has recently bought a Shimano 7000 powered bike, and the experience has not been as positive as with the Bosch system. I initially had sudden losses of power and various error codes appearing, and sudden a drop to eco mode while using Turbo mode when the battery is less than 1/2 charged, something another user has experienced.
Making the battery cradle a tighter fit for the battery seems to have sorted the more random cutting out. It seems more reliable of late, but overall I just haven’t had the same confidence when out as with the Bosch system. The ‘walk’ function, important for tacking steep slopesr/ramps when pushing a heavy ebike, is nowhere near as functional as the Bosch.
It is however useful to have the ‘E-tube’ app to fine tune the levels of assistance. (Now available on the Bosch ‘Smart’ system too).
Giant utilize the proven Yamaha motor in both 60Nm and 80Nm formats to suit their urban and trekking style bikes, although the utility focussed ‘Entour’ models have the high mounted battery, and it appears you need to buy the premium ‘DailytourE+1’ model to get neccessary 8 hub gears for Sheffield.
Brose, TranzX and (increasingly) Bafang Crank drive motors are all capable and reliable.
e-bike tips have a good article comparing the major motor systems here , and Tredz bikes offer a good motor overview here .
These mid motors are found in premium models, along with high quality, reliable cycle parts, and all variants of 50Nm or more will be suitable for heavy duty/hilly use. Shimano even offer Di2 electronic gear operation as they try to woo a whole new cycle public.