Warning Long Post
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Let me try and summarise this thread and my thoughts so far in this quest to find an ebike for off-roading. I have managed to refine my requirements by the process of chatting on this forum, internet research and thinking time, my requirements in priority order currently are:
- Off-road suitability, the bike must be orientated to off-road use/abuse.
In common with non-powered off-road bikes, the frame, geometry, gearing, components and wheels/tyres must be up to the job of getting wet, muddy and crashing, going up steep, slippery hills, jumping over roots, stumps, rocks, powering through thick mud and then being able to go down the same. The motor and battery must be capable of climbing steep hills, so high torque required, the motor and battery must be capable of taking off-road abuse (possibly with some modification), the balance of the bike should not be compromised by the motor and battery. Good front suspension is a minimum, the lighter the bike the better.
- Lighter is better (sub 20Kg).
A lighter bike will not compromise the handling or ease of pedalling when the battery runs out, or you are not wanting to use the motor a good freewheeling motor is a must. It also means it's easier to store and maneuver in the garage.
- I want to pedal and want the e-assist to compliment this.
I don't want a motor to do all the work for me, I prefer to not use the motor except when climbing steep hills/tricky sections or I want a break or it's the end of the day and I just want to get home. When the motor is helping I want to contribute and for the motor to meet my input given the level of motor contribution I have chosen.
- For a kit - ease of kit fitting, Fit and forget type e-assist.
It must be a simple kit to fit requiring on/off switch, battery and motor. Using a system that requires thinking about when negotiating tricky ground will not be good for off-road use. I want to be able to push a button and the motor then just helps out whilst pedalling. This means a throttle system is not a requirement, it's a nice to have.
- Range up to 30 miles with pedal assist.
As the bike is primarily intended for off-road use, then typically distances covered will be less than road distances, 30 miles with pedal assist is good for a day's off-road and will mean the battery can be less powerful and lighter.
Up to £2000, I could be persuaded to spend more for the right bike, but I believe the VFM reduces (plus I've spent too much on road bikes recently!).
High speed - the UK maximum 15.5mph is OK.
Load carrying - seat post rack/bags or rucsac will do fine.
Low rolling resistance - Knobblies?
I've looked at as much of the market as I can for off-the-shelf bikes and kits, there are probably bikes/kits I've missed, but to narrow down my choices I've mainly concentrated on the requirements for off-road suitability and fit and forget. This has ruled out nearly all kits as they are hub motors and the battery/controller would need to be fitted to a rear seatpost (or rack), the motor will also receive lots more abuse being in one of the wheels and hub motors are less suitable for off-road climbing than bottom bracket motors. The only kit I have really considered is the BionX as although it is hub motor, it is more sophisticated and the battery can be mounted more centrally, there are no bottom bracket kits that I am aware of:
- Bionx for an existing bike (full suspension, disc brake, Marin)
A rear hub motor that relies on a torque strain gauge in the hub to measure rider pedal input and adjusts assist according to 4 power levels set by the rider. 4-level battery regeneration is a feature and could provide 'engine' braking on the downhills whilst putting some power back into the battery. Control of the assist is automatic once switched on and works very well when tested on a Trek fitted bike on the road and up hills. Main downside is cost with the 350w or 250w high torque motor and 37v/10ah battery kit needing to be imported at a cost of around £1500. Another downside is weight with around 9-10Kg being added to a 15Kg bike. This is the only kit under consideration because of it's ability to provide input automatically and simply whilst the rider gets on with the job of riding. Warranty work will be problematic with the kit coming from the States.
To narrow my choices for the manufacturers bikes, I have selected the non-hub motor versions and gone for either the Yamaha or Panasonic bottom bracket drive system for their better hill climbing ability, possibly better robustness, central mount for low centre of gravity and assistance methods. Also the weight is out of the wheels so handling should be better, repairing punctures will be easier/faster and disc brakes are easily accommodated. I have spent my time researching kits so far so have not looked into the relative merits of these bikes yet (I have yet to test ride any of these machines, so these are my thoughts based on internet and forum research):
Nice, lightweight, Panasonic system, 28" wheels, around £1800.
MTB frame, Yamaha system 26" wheels (better hill climbing?), around £1700.
Full Susser, V.nice, needs to be imported from the EU at around £4,000 warranty more problematic.
Nice integrated full susser, battery in frame so problematic if it goes wrong (which all batteries do eventually), V expensive at around £8500 imported, warranty problematic. Bit more motorbike like so pedalling not neccesary, heavy and illegal in the UK.
If anyone knows of any other manufacturers bikes worthy of consideration, given the requirements (and removing hub motors from the equation), please chime in.
