eBikes! : Build, Spec or buy ready-made? (Guest Blog contributor: Peter Sharpe)

You may have already seen them – individuals travelling through traffic at seemingly superhuman pace without even breaking a sweat, on bikes adorned with what looks like chunky square lunchboxes or large black/silver waterbottles attached to their frame, and oversized front or rear hubs, or some sort of gearbox at the crank, or any combination of the latter.

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An ebike…

No, these are not a new breed of supremely fit cyclist-mutant riding a specially ballasted training bike (although those do exist), what you’ve more likely witnessed is an e-bike rider.

E-bikes (Read: electric bikes) are a new trend of bicycle which have carved out a new niche and invented a transport segment which didn’t exist previously – not a bicycle, and not a moped, nor a two-wheeled milk-float, but something in-between with all their best attributes and none of their handicaps… (in theory)

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The 1932 Philips & Simplex electric bike

I can recall a time working in a bikeshop in the early 2000’s, when the mechanics refused to service electric bikes due to their weight – they began appearing around this time, and customers would bring them to the shop for the usual bicycle repair jobs but would be turned away. ‘It’s an electric motorbike!’ they would say ‘we don’t service those here!’

On the one occasion we agreed to service one (a puncture repair) the ebike in question was heavy to the point that the workstand was not strong enough to hold the bike… it just so happened that the workshop used to be an MOT garage and was still equipped with an engine hoist, which was used to lift the bike and perform the work.

The same shop now some 12 years later, has very likely changed its tune in a big way – they would probably very much like those same ebike riders to bring their bikes back in for servicing, and sell a few new ones to boot! (Think three figures and up…)

The technology that has made e-bikes possible and practical are new higher power-density lithium ion batteries (which are oversized, but light-ish laptop batteries), miniaturised AC and brushless DC motors, and cleverly packaged miniature electronics that comprise the motor controllers.

The source of manufacture of the plethora of e-bike components is where you’d expect: China and South Korea, predominantly. The industrialised mass production of ebike kits to be sold to bicycle manufacturers, or the amateur hobbyist, has made it relatively cheap and accessible for curious individuals who are interested in entering the new exciting world of ebikes.

So to come back to the headline question – to build, spec or buy? Let’s say you’re interested and intrigued, you’ve probably already considered the options;

  • Build one from a kit with your existing bike – many online vendors are now selling ‘ready-to-go’ ebike kits which are advertised as being quick and easy to install… ‘assembled in 1 hour!’ they claim. (The reality is not quite so straightforward as I’ll explain…)
  • Spec one and have it built for you by a professional – provide your existing bike with your desired ebike kit, and have a friendly bicycle mechanic build it properly for you – and even service the bike while he’s at it. (We’ll talk about this too)
  • Buy one ready to go – OK Mr moneybags, go ahead and by one off the shelf – this is all fine except you’ll pay at least 2-3 times the cost of building your own ebike from a kit… and if you can afford that stealth bomber ebike then you go ahead and crack on!

My personal choice (as an aircraft engineer) was the first option, which, as well as making it customisable, gives you (and crucially gave me) the prerogative to enforce the applicable rules of your own volition

Having decided to undertake building an ebike, the follow are some of the options you will then have to choose from;

Front Wheel Hub Motors

These replace your front wheel with a bolt-in wheel that has an integral hub motor and a cable running from the axle to a controller and battery that you install on the bike. The hubs are usually drilled with the ISO (international standard) 6 bolt disc pattern, or rim brakes can also be used instead.

Crucially, hub motors have special tabbed washers that engage with the fork dropout – these react the thrust torque when the motor is under power. (Pictured)

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Technically the front hub motors is the easiest and lowest impact option to install on the bike, but some thought should be given to the extra weight up front and it will also affect the bike handling under power – this configuration is best for city bikes & commuters.

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Rear Wheel Hub Motors

Rear hub motors are the same as the front hub motors except this is where the human-powered cogs live – your cassette and freewheel.

The hub motors I’ve come across in the online stores on ebay / amazon etc. generally seem to have the option of screw-on freehubs or slide-on cassettes. If you are building an ebike for a 9-speed freehub and want to re-use your cassette from your old wheel then you will want the slide-on cassette type instead of a screw on freehub, but this is academic as you can also get the screw-on casettes with the right number of gears too.

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Front AND Rear Hub motors

Disclaimer: Some individuals in the ebike community have taken to installing both a front and rear hub motor on their ebikes for extra power…but now you also need an extra battery, extra controller, extra pedal sensor – double up on everything. This is silly, don’t do this!

Mid-Drive / Crank Drive Motors

Mid-drive motors are seemingly found on the higher-end ready-made ebikes more frequently – mountain bikes in particular. They seem to be the logical choice for full-suspension mountain bikes because they keep the weight more central and within the ‘sprung mass’ centre of the bike frame, rather than on the wheels which are subjected to higher shock loads.

Also, the mid-drive motors are typically reduction geared through a small gearbox so they can produce maximum torque to the crank at whatever speed your pedals are turning – this is more efficient because it allows the motor to work at the effective ratio that you’ve selected with your gears.

Be warned however, the mid-drive motor gearboxes often use nylon plastic gears, which wear out quickly, so the useful service life is limited if they’re ridden aggressively in harsh conditions (muddy/wet).

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At the beginning of this post I described 3 ways you might find yourself taking the plunge into ebike ownership, these were;

  • Build one from a kit with your existing bike
  • Spec one and have it built for you by a professional
  • Buy one ready to go

In the end I spent around £600 on my ebike build, and I learned by trial and error how to do it. To have something equivalent ready-to-go from the shop you’ll be looking at nearly £2000, and judging by my trials and tribulations you might not fancy doing it yourself? You can read about this in more detail in my following guest post (I must have impressed Chris & Claire!)

The cheapest and easiest alternative then, is to have your ebike built for you – provide the bike and the e-bike kit and let Spokey Dokey Bikes do the work!

Or, even just provide the bike, and Spokey Dokey Bikes can find the perfect ebike kit and fit it for you, to get you going with your new enhanced speed machine.

So if you like the sound of an ebike and don’t want to break the bank, trust Chris to put one together for you, or any other kind of bike for that matter…?

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