Tuesday, February 03, 2009

e-biking the Long Mynd


How feasible are electric bikes in a hilly area?

Two weeks ago we hired some Kalkhoff Algattu electric bikes from Church Stretton. As it was our first time, we chickened out of tackling the Long Mynd – a 1 in 5 climb straight up from the west side of the town – and headed eastwards instead.

As Prospectors, we like theory and experiment – sometimes we get to combine the two. First of all, we worked out how much energy (in theory) it takes to propel yourself and your bike up the Long Mynd (a 900 foot climb up a 1 in 5 slope) (a) on a regular bike and (b) with full power assist on the Kalkhoff.

At 4mph on a regular bike our model said we’d need about 350w. Even as an experiment, I reckoned that would be beyond me. On a Kalkhoff Aggatu (with full power assist), the model predicted I would need only about 150w at 4mph. That is the same energy as is required to pedal the same bike at just under 20 mph on the level in still conditions. I thought I could do that, though whether I could keep it up for the whole climb remained to be seen.

So we returned to Church Stretton for a practical test. Our model said we ought to be able climb the Long Mynd at 4mph, but would our legs agree? We were also interested in how long the batteries would last if we tackled that kind of hill on full power. As it happened, the rental folks at Central Garage had forgotten to put the batteries on charge so we found ourselves setting off with the batteries already down to their last third and ominously flashing their indicator lights. That certainly focused our attention on battery drain! - we didn’t think we would get very far but were still interested to see how far, and what it would be like.

Fortunately, we were wrong! Firstly, we happily pedalled (at a fairly steady 4mph as it happens) all the way up the steepest hill I have ever attempted on a bicycle. The power assist meant that we never found ourselves going so slowly that we wobbled and although one of us stopped a couple of times to admire the view, it wasn’t strictly necessary and the power surge made it delightfully easy starting off again up the slope.
e-Cycling up Long Mynd
We reached the ridge in about 25 minutes – much more quickly than we could have walked it – and were amazed looking back down the valley to the town to see how high up we were.
e-Cycling up Long Mynd
Free-wheeling back down to Church Stretton was, however, alarming. I had not realised just how steep the hill actually was until then. But, back at the bottom, we still felt amazingly fresh and since the batteries (whilst still flashing) seemed to be holding out, we did another few miles to explore Cardingmill Valley below Long Mynd, to see what happened when the power finally ran out. But in the end, we had to deliver the bikes back to Central Garage with some power still left in the batteries. Amazing!

So, we are now fairly happy that these bikes can manage hilly terrain at least for a short duration and the novel experience of ‘cruising the hills’ (for a couple of ‘amateur’ cyclists who aren’t looking for a workout) is compelling. Even with a 27 gear mountain bike, we reckon you would have to be pretty fit to tackle the Long Mynd without getting off and walking. You need to travel at 3-4 mph just to keep your balance, and if you stop to get your breath back, you would have trouble restarting on the more extreme parts of the slope.

Bring on the Brecon Beacons…..

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