Hub motors and mid-drive motors on electric bicycles – What’s that all about?

Hub motors and mid-drive motors on electric bicycles – What’s that all about?
August 10, 2018 Ken Ching

One of the most common questions that prospective buyers of electric bicycles have, is whether to ‘go mid-drive or hub drive’. Even people who don’t think to ask such a question are often bombarded by friends, sales people, manufacturers etc about which is better. What is it that they’re all on about and why is it even a thing?

Maurice from EBike Team in Auckland, our eZee Bike distributor gives you the run down. Originally posted on ebiketeam.co.nz

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What are the options?

There are two general categories of electric bicycles for sale in NZ (and Australia, U.S. and many other places).

1 – “Hub-motor e-bikes with throttles” such as eZee Sprint and more. These e-bikes are often from specialty e-bike companies as opposed to established bicycle manufacturers.

2 – “Mid-drive e-bikes”, eg e-bikes equipped with the motor drives by Bosch, such as Cube and many more. European e-bikes are highly represented here, though there are plenty of factory generic options coming through as well.

It’s a lucky thing e-bikes are inanimate objects, as generalisations on these categories are unavoidable. And although there are always exceptions, the generalisations are definitely useful:

The hub motor category is more transport-oriented and excels in the nuts and bolts of transport – they go faster, have bigger batteries and are more affordable. The geometry and sizing is usually more ‘shareable’, fitting a variety of people. They almost always have throttles and cadence sensors, though the use of torque sensors in this category is growing. The bikes hold a bit more mass-market appeal, more likely to be built with function over form and don’t generally target the existing cyclist market.

The mid-drive category is almost synonymous with the european market, for reasons we will get into later. The choices in this category are more like non-electric bicycles in many ways, including aesthetics, geometry and sizing, ride feel and component choice. These are generally made by existing bicycle manufacturers who have a ‘bike first’ design philosophy, prioritising the non-powered nature of the vehicle over things like battery size, power, top speed etc. These bikes almost never have throttles and almost always have a torque sensor to help the bike know when you want power. They are generally slower, with most not giving assistance above 25kph. However, that is very quickly changing with more available at 32kph and 45kph.


Which option is the best?

You probably know I’m not going to answer that, they’re both great options and the beauty is that they are very different to one another. For an MTB rider that plans for both wheels to leave the ground at the same time, we will generally recommend a mid-drive. For an everyday rider who wants to do the occasional wine trail, the case for the hub drives is very strong, though plenty of people will prefer a mid-drive too.

I stick to the advice that you need to ask yourself (and your supplier) the following about any bike you’re considering.

1 -Do you feel confident when leaving the house on this e-bike, that you’ll have an enjoyable and safe ride that will make you want to use it next time you leave the house?

2 – Do you feel comfortable riding this electric bicycle?

3 – Can the electric bicycle go up hills with an amount of assistance sufficient to your needs/desires?

4 – Can someone service this electric bicycle for you, are spare parts available now and will spare batteries be available in 5 years?

What are the latest trends in the technology – why can’t one system have it all?

Since writing the original article, what’s changed in two years? Well, nothing that makes any of the original information inaccurate. However, there have been changes to what’s commonly for sale. In particular, there are many more hub motor e-bikes available with torque sensing systems, which was previously the domain of mid-drive e-bikes. And vice versa, there are many more mid-drive e-bikes available that can go faster than 25kph, previously the domain of the hub-motor bikes. This blurring of boundaries will make it even harder to draw any useful generalisations and therefore a little harder to decide in one sitting at your computer which bike to buy! However, deciding what to buy before you’ve ridden it never was a good idea. In reality these extra options mean it’s easier than ever to find an e-bike that you love, you may just find there’s a few more on your list to test ride than you first thought!

Bikes like the T4 torque sensing series of eZee bikes (Sprint Alfine T4 etc) are truly a ‘best of both worlds’ situation, with power in proportion to your pedalling achieving a smooth, natural ride, but still with the big batteries and heaps of power to go up any hill and higher top speeds.

Then we are also seeing the mid-drives offer higher speeds, with 32kph becoming an option for many brands, notably on most Shimano bikes since 2017 and some Bosch bikes from 2018. They still don’t have throttles and huge batteries, but for someone who wants to do most of the pedalling work but wants to go quicker than 25kph, this is also a ‘best of both worlds’ offering. It truly is exciting times for e-bike shoppers!

Why can’t one bike have it all and we can do away with these divisions? Some constraints certainly are artificial, such as a speed limit imposed in a different continent affecting what you can buy today, that’s a solvable problem. But other constraints are real – why do the e-bikes that feel most like a bike, not perform as well on the electric side? Because they’ve got a lower weight and space budget for robust motors and large batteries! Why do they cost more when they try to cover all bases? Because they’re having to spend more to accommodate competing interests. Evolving technology can cover some of these issues (eg lighter battery cells), but some are fundamental questions about what’s most important to you. Upright bikes are more comfortable but they’re less aerodynamic and are less suitable for swerving downhills on windy tracks – that’s a fact of physics and technology won’t change that. When riding on Tāmaki Drive shared path and getting buffeted by wind over a bridge, a heavy-set e-bike is your friend, but you won’t feel that way if you try to lift it onto a poorly designed car rack – technology won’t change that either (though a better car rack will).

There is a reason after all, why there is more than one bike to choose from! Take advantage of that fact and choose one you’ll love!

Further reading – Why do these different categories even exist? Click here


 

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