My Modified Bicycle

Now with Bionx electric motor

Thanks to Professor Saleh, my right leg has now regrown the lost 4" and my knee bends to about 95º, which makes some things a tad tricky - good for tripping people up whenever I'm sitting down, or at least it would be if it didn't make my leg feel like it would fall off. I need to build up muscle strength, in addition to general exercise but I must avoid all impact activities; so on doctor's orders, I mustn't run. Cool, thanks Mike! Cycling is ideal but as I have not enough flexion to ride a conventional bike, I have had my bike modified. Friend Tony came up with the design and the work itself was done by Colin White - a Top Cycling Engineer!

From my knee flexion we calculated the maximum height my foot can reach at the top of a pedal revolution. Colin then split the crank into two lengths: the total length is the standard 170mm, allowing for normal leg extension at the bottom of a pedal revolution; at the top of the revolution, one length of crank pivots around the other, thus reducing the overall length of the crank. In the photo below, my foot is pretty well at the top of the pedal cycle, near my knee's maximum flexion at the time, although it has since improved.

Bike
Trek 7300 hybrid c1999
700c wheels now with 32mm Continental Ultra Sport on the front and 37mm on the back
13/21 Zenith 7 speed freewheel
22/32/42 chainset (will change to 50 probably, and maybe just a single ring)
Thudbuster LT suspension seatpost - (together with the narrow tyres this makes for a faster, smoother ride than fat tyres on their own)
Dinotte li-ion lights: x2 5W bar and helmet, x1 rear on seat post (not shown)

Kit - from NyceWheels
Bionx 350w with 36v lithium ion battery
pedal assist and thumb throttle
7 speed freewheel

Reason for getting kit
Exercise for my leg, both for flexion and muscle strength
General exercise
Cheaper commute to work (I get paid to cycle!)
and I wanted to 'fit it and forget it'.

I tried an Ezee Torq but decided against it as I already had a good quality bike and wanted to add a kit to that that I could put on another bike, possibly a recumbent, if I wanted to. The Ezee Torq, however, was enough to show that an electric bike was the way for me to go.

After much research online I opted for the Bionx kit:
light, to keep the feel of my bike appeared
It was well reviewed but it was hard to find users' opinions
it looked like a good package - I wanted something that would fit easily and require as little maintenance as possible.

Finding a dealer - I live in England
I contacted Bionx who recommended NyceWheels and I also found Juergen on tech.groups.yahoo.com/group/power-assist. Both Bert and Juergen were very helpful but in the end NyceWheels had the stock in and they were able to supply, together with a freewheel to replace the cassette mechanism that won't work with the Bionx. The kit has been pretty much a case of fit and forget it, but I have contacted Bert a few times and he could not have been more helpful - if only NyceWheels weren't a few thousand miles away.

Buying process - went without a hitch. I wired the money to NyceWeels and they sent the kit, sans problems.

Fitting the kit
Tony helped and we fitted the kit with no problems at all and were both impressed at how easily and how well everything slotted together - obviously well thought out. The only very slight thing that doesn't tie in with all this is the charging socket on the battery with is open to the elements, so I stick a bit of Blu-Tac over it to keep the rain out - maybe it's waterproof anyway.

Battery
Charges in less than 4 hours after which the charger turns itself off. One word re the fan-assisted charger: be sure to set the voltage to the correct amount on the little recessed switch (110v/250v).
The battery mounting mechanism on the downtube is great.
Once fitted, the only way to remove the battery is with a key - I dare say the lock can be picked but you can only do so much to avoid theft.

Console
It fits on a cycle computer type mount and then a screw goes into a hole in the bottom 'locking' it, so to remove it would require tools - again handy for theft prevention.
The console can be locked which puts the system in maximum regeneration mode making it very difficult to pedal away, but easy enough to push... The alarm that sounds is more of a squark and I can't see it making any difference to a thief to be honest.

Motor
The wheel is not quick release, if anything this may be better as again it discourages theft.
Not much more to say about the motor - it's discrete, makes a barely audible electric milkfloat type whine when assisting, but its weight does make the ride harsher.

First ride
Easily able to keep up with Tony's pace of about 20+mph but gearing meant I could not keep up with him when he pushed on downhill or on the flat. However, up hills, I was easily able to leave him far behind although I was very impressed by his turn of speed once he'd crested the hills. Downhill, the regeneration mode worked very well at slowing speed; the way it is hooked up the (front) brake level works very well too and does wonders for the braking distance. As for actually charging the battery, I think you'd need a pretty hilly ride to notice any difference in range, but I think it is worth it just for the braking assistance.

First 3000 miles
I have not used it quite as much as I'd hoped but, even so, have done just over 3000 miles in 18 months, in all weather - no problems in the wet. I don't like the hard, slick tyres on icy roads so tend to use just the motor over icy patches that I see - or get the bus!
No real problems - faultless motor and battery. The console started showing a less than full charge but there is a re-set option on the console that sorts that out. I broke two spokes on the rear wheel after 1000 miles, then it was fine till about 3000 miles when two more broke, so I got the wheel re-spoked, with spokes supplied by NyceWheels as I couldn't source any decent ones locally.

In use - very pleased indeed. I can put in as much or as little effort as I want, and use a combination of pedal assisted and throttle assisted riding - bear in mind I have limited knee flexion and strength, all the more so because of the modified crank which restricts leverage. Most of my riding is currently at maximum pedal assistance, and I often use the throttle too. In time my leg will be stronger and I could well ease off on the assistance.

Range - because I am currently using maximum assistance nearly all the time, 20 miles is about the limit on fairly flat ground. However, from experimenting over shorter rides with lower levels of assistance, I think this could quite easily be doubled and still give you an easy ride.

Speed - I weigh about 11 stone/70 kg and the narrow slicks help a lot too, and the bike itself is reasonably light, which all goes to help the speed. Unassisted I can get up a half mile long 10% hill at about 14mph, but I normally pedal and can get up most hills around here in top. My top speed is limited by the gearing as I cannot spin fast enough to keep up so will change the chainset in time, probably to a 50 tooth or maybe 52 tooth ring. When you get to the speed limit the system gradually shuts down rather than simply cutting off but, even so, there's an odd sensation when it does stop as it feels like the wind has suddenly picked up! That does not seem to happen so much with the thumb throttle.

The only time I drop through the gears is to pull away, whereas before the Bionx, most hills saw me down to bottom gear - 11 on the rear cog and 22 on the front.

Generation mode - I have not done any tests to see how much this extends the riding distance but I'd guess you'd need to live in a mountainous area to get the most out of it. I do use it though as I figure every little helps, and have not had any problems with it - no vibration or overheating. The thing I like most about it is the reduction in braking distance.

General
I wondered how well the Bionx would cope with the disparity in power between my strong and weak leg but it generally copes fine although sometimes it will cut the assistance when I am cruising - presumably because my effort is insufficient for the system to think I need a hand; a slight increase in pedal power sorts that out though, and I am guessing that most people might not experience it as both legs would be pedalling equally.

It works extremely well for me and has opened up a whole new world as although I used to be very active, my weak leg has seriously limited what I have been able to do. In short, I think everyone should have an electric bike, as it flattens the hills, negates the wind but is still very much a bicycle rather than a scooter.

Buying the Bionx was a bit of a risk for me as I couldn't try one out and was wary of sending all that money across the Atlantic, but NyceWheels couldn't have been more helpful and the kit itself is exactly what I wanted. Now, if only it cost 50p and a conker...

Most of my commute: