ASO MILL Blog

New e-bike motor 自転車モーター交換

春に作ったEBikeには最近問題が発生しました。

The lovely eBike I converted to electric in the spring has hit a few problems recently.




▲ モーターからチェーンが2回外れましたが、2回目にコグが爆発しましたのでもう使えない状態です。同じ風に修理したらまた同じ問題が発生する可能性がありますので違う形のモーターに変更します。

The chain flew off the rear motor twice (it was a couple of degrees off straight), and the second time the flywheel kind of exploded slightly, losing all the ball bearings inside. That's the brass bit in the middle of the photo. So even if I replace that part, it's possible that it might happen again at some point, and it might be a loooong walk home.

▲ 今回フロントホイール用のモーターを付けます。モーターがホイールの真ん中に付けないといけないので、スポークの付け替えも必要です。YouTubeのビデオを見ながら変更いたしました。

ますは前の長いスポークをすべて外しました。

So I decided to try a front-hub motor this time. The previous motor was connected to the rear wheel via a chain system, but this new one (from AliExpress again) fits right into the centre of the front wheel instead. Unfortunately that means you either have to buy one already mounted into the correct size of wheel, or replace the spokes on the existing wheel to fit the new motor.

After checking some YouTube videos, I was fairly confident this could be done easily-ish, so I removed the front wheel and unscrewed all of the old spokes.

▲ ビデオのとおりにモーターを真ん中に置いて新しいスポークを入れました。

The new spokes are shorter, to fit the bigger motor in place of the slim axle, and I had to guesstimate the length (using an online calculator) and order some from Amazon. Then, following video instructions, I started to add spokes...

▲ スポークを注文したときにできるだけ正しい長さで計算しましたが実は５ｍｍほど長すぎでした。空気入りタイヤならパンクになる恐れがありますが、去年ソリッドタイヤ―に変更しましたので、パンクなれないタイプです。ラッキー！

... and eventually all 36 spokes were in place. Then it was a fairly easy matter of placing the wheel back on the frame and systematically tightening up the spokes in turn, to true the wheel and remove wobbles. My spokes turned out to be about 5mm too long, and normally this means they would protrude inside the wheel and potentially puncture your inner tube. Happily, I switched these tyres out for solid ones last year (I was tired of constant flat tyres), so they are puncture-proof. Yay!

▲前と比べたらモーターが小さくて軽いですので、カッコよくなったですね。パワーが同じ３５０Ｗです。急な坂道の所にちょっと足も使わないと早く進めないんですが、満足です。

Compared to the previous chain-driven rear motor, this fronthub motor is lighter, quieter and smaller, and I was still able to use the existing batteries, throttle switch and cables. The power (350W) is the same, which means I need to add a bit of pedalpower on steep slopes to keep it moving along, but I'm still very happy with it. With a top speed of somewhere around 35km/h, it's great fun!

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