Had a go on my brother's electric assist mountain bike last weekend, a Trek Powerfly 7+, to see if it would let me get out on a bicycle but allow me to keep my heart rate down, which on a normal bicycle had proven pretty much impossible on any kind of moderate gradient (5-6% or more). Even slowing to a crawl I would still see my heart rate climb up above 150 bpm, well over 80% of my max. Since I had been told to keep it to about 60% (not compatible with cycling at all) that was a real problem.
Anyway, the e-mtb made getting up the same moderate hill a breeze, in fact instead of my wife having to wait for me at the top, she rapidly disappeared backwards.
On anything other than a climb the assistance cuts out completely above 15.5 mph (25 km/h) so not surprisingly you spend a lot of time cruising at 15.5 mph, since pushing faster takes a step up in effort and slowing down just increases the assistance, which speeds you up again. Once warmed up, I found I could dispense with the assistance most of the time and cycle along at about 18 mph with my heart rate below 130 (around 70% of max), just using the assistance to get over the inclines without pushing it any higher. You guys would clear off on the flat (as doing over 20mph would mean too much exertion), but on any kind of a gradient it just romps away from anyone with pedal power alone.
Not ideal for cycling with my mates then, as I'd rarely be going the same speed, struggling to keep up on the flatter bits and dawdling on the climbs.
I decided to go up the Merry Harriers climb (from last winter's Chain Gang) to see how I did, as no way could I get up that on a normal bicycle without exceeding 160bpm, unless I walked. I found that trying to get anywhere near the maximum assist still pushed my heart rate too high, so going up at 15mph would still need a lot of effort, but by dropping back to around 9 mph or so, my heart rate settled at c.135 bpm.
This meant that I just beat my best time from March (pre-stroke), which was about 8.5 mph average, but with my heart rate around at least 40 beats lower. When I got to the top I was completely fresh, not surprising as the electric motor had probably put out more power than my legs. I met a couple of women resting at the top who I had seen earlier, so stopped to say hello. I felt a strange compulsion to apologise for the electric assist, and make my excuses for using it, as though I had been caught "cheating", but they hadn't noticed it was an e-bike! I think I would spend quite a bit of time apologising to "real" cyclists (and perhaps being sneered at by some), but it's that or no cycling at all.
I was lovely weather, a perfect Autumn day for cycling, no wind, moderate temperature and blue sky and sunshine (loads of cyclists out on the roads), and I was able to get out an enjoy it. Nearly a week later and I've had no repercussions medically so far, so hopefully it's a sustainable exercise for me.
Going back down the steep gradient did show that the mountain bike format was not the best for the road (or for me), as the feel was very different to a road bike and the very wide mountain bike tyres (c40mm and 50 psi) felt like they were giving a lot of resistance, the handling was not exactly pin sharp. Still, it hit 36 mph on the short descent, even sat pretty upright as you are on a mountain bike. At 21 kg, it was never going to handle that well!
I decided that what I really needed was a "normal" road bike with electric assist to get me up the steep climbs without risking another trip to hospital. I had a quick look when I got home and luckily Giant have just launched a couple of e-road bikes (Giant Road E+ 1 and 2), which looked pretty ideal. The higher spec one looked just like my trainer bike (alu frame, 105 groupset, 22 gears, 32mm road tyres on hydraulic braked wheels) but with the motor housed in the crank and a 500 wh battery in the frame.
Should be about 7 kg more than the similar road bike as the motor is 4 kg and the battery 2.5 kg, plus some accessories, so perhaps 18 kg or so in total. I'm hoping this will be very similar to a road bike in feel, since weight only really counts when accelerating (including climbing) and on the flat and descents the air drag and rolling resistance should be more or less the same, with drop bars and similar geometry. On a climb, of course, the extra 7 kg or so (only about 7-8% of total weight of rider plus bike) will be more than made up for by the up to 250 W motor kicking in. This should mean I can keep up with friends everywhere unless they really go for it on the flat, in which case I will have to catch up on the next climb! :-)
In fact, when you think about it, this kind of electric assistance has a lot going for it, not only for those of us with medical issues or as we get older and less fit. One thing about a long cycle ride is that churning up the steepest hills can take a long time and going so slow can be a drag. There is nothing to stop a fit cyclist riding a e-road bike giving it all they have everywhere, dispensing with the assistance everywhere other than the climbs, and using it to add to their maximum efforts on the steep climbs to increase their speed toward the assistance limits. Going up Alpe d'Huez at 15mph on a 18kg e-bike would still leave you exhausted, it would just mean the scenery would change faster and you would feel "you were getting somewhere". You could always do a longer or steeper climb if you wanted more challenge.
It's not going to replace the thrill of a ultra light weight bike and making it up the steepest climbs under your own steam, but I really think that as batteries and motors get smaller and lighter, a little assistance on the slow grinds can only make cycling better, as well as more accessible.
My wife and I are planning our retirements around a couple of e-bikes and meandering around France. Keeping fit and having fun at the same time.
P.S. I also had a go on his Kawasaki Z100SX motorbike over my favourite cycling route, and although average and maximum speeds were considerably higher, I preferred the lighter more "part of the scenery" feel of cycling. I decided I'd rather have a £2,500 e-bike than a £10,000 motorbike, and no insurance, tax, petrol, leathers, traffic cops, etc. make it an easy choice!
Cheers,
Geoff
P.S. Desperately missing the bkool rides, I wonder if a winter league where heart rates have to stay below 140 would be popular? "Racing" with a heart rate limit might be a little difficult ...
Game on!! 
. No idea how I got the time. Some strange quirk of bkool working in my favour I think.
