Advice for a heavy rider

[hedgemonkey]

I have done a fair bit of reading and think that I like the look of the Woosh Sirocco CDL as I have a 10 mile each way route to work with some big Mendip Hills to cope with. I'm 6 foot 4 and currently 19 stone but from past experience would get down to 17 stone in a couple of months.
The Woosh website warns against riding one if you are over 17 stone, presumably because they think it will strain the motor. Any thoughts from other members? I know they also have the Big Bear model but I wanted a crank driven bike as some of the hills are a mile of 15%.

 

[Jonah]

I think this bargain Kalkhoff would be ideal in 55cm frame. http://www.50cycles.com/electric-bikes/urban/sahel_premium_i360_harmony.html
Admittedly a lot more than the Woosh but a super quality bike. I don't think you would need to worry too much about the weight warning on the Woosh.

 

[trex]

I think Woosh encourage heavy riders to buy the Big Bear because Big Bear has better torque on roads under 10% gradient (the yellow load line) and does not wear the chain.
To work out how much you have to pedal, select the desired speed, then follow up vertically on the plots. If the motor performance is above the load line, the bike can cope on throttle alone.
Woosh may have upped the torque on their Big Bear, that means you may not have to pedal at all on 15% hills. Otherwise, you have to make up the difference with pedalling. Humans can produce between 100W-200W on hills. If you pedal hard, you can get about 7mph on 15% gradient (blue line) with 2013 Big Bear.

 

[hedgemonkey]

I think Woosh encourage heavy riders to buy the Big Bear because Big Bear has better torque on roads under 10% gradient (the yellow load line) and does not wear the chain.

 

[hedgemonkey]

Is the danger of being too heavy on the CDL that of damaging the motor or the chain? A damaged chain would be easy to replace but not a motor.

 

[trex]

you can stall the CDL motor on hills, that's what they are worried about. This said, the CDL can climb 15% hill on first or second gear with your weight.

The CDL has only 7 gears, disregard plot for gear 8. It can climb 15% gradient on throttle at 6mph on gear 1. You have to pedal on gear 2 but up to a much more comfortable 8mph.

 

[Deleted member 4366]

Are those hills really 15% for a mile, or are they a mile long with a short bit 15%, like this one that averages 7.5%, but has a steep bit at 18%. The Woosh big Bear would give you a much easier time up this hill than any normal crank-drive bike.

 

[hedgemonkey]

Are those hills really 15% for a mile, or are they a mile long with a short bit 15%, like this one that averages 7.5%, but has a steep bit at 18%. The Woosh big Bear would give you a much easier time up this hill than any normal crank-drive bike.
View attachment 8708

The hills are only 15.5% at their worst, I suppose they aren't that steep, this is Somerset, not the Alps. Using Hatti's prediction engine it says a round journey of17 miles with a climb and fall of 250m at the start and end of the journey.
I have no expectation of the bike taking me up a hill by throttle, in fact I would happily have a bike with no throttle at all as the only reason I am buying the bike is to get fitter.
What does it mean when an electric bike motor "stalls"? Too much load and it just stops turning?

 

[trex]

The CDL is a little faster if desrestricted but I think the Big Bear is better for you.
Much more relaxed ride, less worry about selecting the right gear.

 

[RobF]

What does it mean when an electric bike motor "stalls"? Too much load and it just stops turning?

Something like that, but don't worry about it - the motor will stop turning before it damages itself.

In any case, you will be a wheezing wreck by that stage.

But I don't think it will happen as you will be able to get up the hills in your area one way or another.

Either of the woosh bikes will do the job well for you.

You like the CD and crank drives encourage the rider to pedal which you want to do.

Conclusion is obvious - buy the CD.

 

[JohnCade]

I'm undecided between those bikes too. While the CD will encourage pedaling it will also put a lot of stress on the drive chain components. The combined effects of motor and leg power make for pro rider levels of wattage going through them which would cause severe wear in a hilly area. Particularly with a heavy rider I should think.

Then there is the problem of changing gear under load on a CD. Even if using a work around like touching the brake for a moment to get smooth changes that would detract from the rider experience I would think, since you couldn't just ride it as you would an unpowered bike and change up and down regularly and easily to suit your cadence. As well as adding to the wear issue.

The BB will obviously need less maintenance and replacement in the drive chain department and should shift smoothly enough without the loaded chain; and while it might be a bit more laid back it will still need some peddling on steep hills. As well as allowing extra input when you want for fitness of course.

It's just that you wouldn't necessarily have to put in as much leg input as on the CD most of the time, you would need to want to. Which does give added choice I suppose.

 

[Deleted member 4366]

What does it mean when an electric bike motor "stalls"? Too much load and it just stops turning?

Once motors go below about 50% of their maximum speed, the efficiency goes down. Efficiency is the difference between input power from the battery and output power. The difference is converted to heat. The controller limits the maximum current, which you get when you're below about 50% maximum speed (depending on the controller), so, as you slow down, you get less and less power, which makes you slow down more until you eventually stop.

When the motor is stalled, you have zero efficiency, so all the current that the controller will allow goes to heating up the motor. Normally disaster occurs within a few seconds, so you must never let your motor stall. You can feel when the motor doesn't have enough power to keep going, so you either pedal harder or jump off and push. In theory then, the motor will melt if you stall it, but in practice, the controller normally goes first. I'm not too sure why because it has current limit and temperature limit, but when you stall the motor, it's common to blow a FET in the controller, which is terminal (for most people).

There's more bikes now with high-torque motors, so stalling doesn't happen so much. The big Bear's motor is quite a slow wind, so it can maintain reasonable efficiency to a relatively low speed, which means that it can make more power than others when going slowly, so you can climb steeper hills. It also gives more torque because of its size.

 

[flecc]

Then there is the problem of changing gear under load on a CD.

With a hub gear, it's best with a crank drive to plan ahead as much as possible and get into the right gear for a climb before starting it. Even when the gradient varies thoughout the hill that's possible using the chosen gear, varying the cadence (pedalling speed) to cope with the variations.

 

[Cyclezee]

Hi Hedgemonkey,

More money than the Woosh bikes, but all eZee models have torque and load capacity that would give the performance than you are looking for.

 

[JohnCade]

With a hub gear, it's best with a crank drive to plan ahead as much as possible and get into the right gear for a climb before starting it. Even when the gradient varies thoughout the hill that's possible using the chosen gear, varying the cadence (pedalling speed) to cope with the variations.

Yes I read a post from a CD owner who said that was the way he did it. But as I posted above, doing that changes the experience of riding; and the nicest way to ride a normal road bike is to keep a steady cadence as much as possible and change gear frequently to keep to it.

So having to change cadence on a hill all the time is a negative for this bike. It means the plus point of crank drive which is the normal bike riding experience plus extra power is largely negated.

 

[Deleted member 4366]

I can't understand this obsession with normal bike riding. If anybody wants their bike to be like a normal one, get a normal one, otherwise enjoy all the advantages of an electric one - like not having to change gear so much.

 

[JohnCade]

I can't understand this obsession with normal bike riding. If anybody wants their bike to be like a normal one, get a normal one, otherwise enjoy all the advantages of an electric one - like not having to change gear so much.

Leap tall buildings and fly like a bird....

Actually I'm not sure I do want a normal unpowered bike experience nowadays which is why I'm leaning toward the BB. A few years ago I wouldn't even think of buying an e bike but fings ain't what they used to be.

I'm setting out the pros and cons, and I suspect many e bike buyers quite like the idea of having a normal bike experience and also have the legs of Miguel Indurain. Particularly the ones with any background in road bikes.

 

[Deleted member 4366]

I can remember years ago. You used to get competitions to win a car, where you had to rate desirable features in order of preference. They were a type of market survey.

Always, sunshine roof came out near the top and air conditioning at the bottom. Why? Because nobody had ever tried a car with air conditioning, so they didn't know what the advantage was, particularly as the car was a low-end one.

 

[flecc]

I'm setting out the pros and cons, and I suspect many e bike buyers quite like the idea of having a normal bike experience and also have the legs of Miguel Indurain. Particularly the ones with any background in road bikes.

True of me too John, but e-biking is different, and as much as we might try to make it normal bike riding, it never really is. And of course the points you made earlier emphasise just how different crank unit and hub motor riding can be.

 

[JohnCade]

I can remember years ago. You used to get competitions to win a car, where you had to rate desirable features in order of preference. They were a type of market survey.

Always, sunshine roof came out near the top and air conditioning at the bottom. Why? Because nobody had ever tried a car with air conditioning, so they didn't know what the advantage was, particularly as the car was a low-end one.

Still if the advantage is too great you might as well buy a motor bike. I've had a lot of them over the years too and they don't do much for aerobic fitness.