Up hill struggle

carbolts

Finding my (electric) wheels
Nov 2, 2014
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Hi
I have just bought a Trek 7.3 FX bike and I want to convert it to electric.
Im planning on traveling between 5 and 10 miles a day on a hilly round trip to the post office, depending on the route.
I have contacted whoosh bikes and they have advised I get the front BPM700 kit for my bike.
I was wondering if anyone had used this kit and what it is like up hills?
I live in a very hilly area with one very bad stretch that goes up aprox 250ft over 1/5 mile stretch or up 100m over a 250m distance.
Do you think the bike will go up this hill without pedeling? I weight around 75Kg and the bike is around 12kg I think.
Thanks for any help or advice you can give me.
John
 

trex

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May 15, 2011
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no, it can't go up 40% (1 in 2.5) gradient (100m over 250m).
No bike can.
Going up 250ft over 1/5 mile (75m over 320m or 23.6 percent), the BPM can just about do it with pedalling though. The Woosh Krieger might do it without pedalling. It has the same power as the BPM but you can go up slowly in low gears.
 
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carbolts

Finding my (electric) wheels
Nov 2, 2014
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Thanks for the reply. Looks like I may have to take the long route round.
If I bought a 1000w front wheel motor from ebay Would that be able to handle it?
Cheers,
John
 

trex

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May 15, 2011
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No. Those 1000W kits use direct drive motors, excellent for high speed but useless for hill climbing.
You'd need a CD kit, BBS02 500W or BBS02 750W.
Woosh have BBS02 36V 25A 500W kit - the last time I asked, it costs £359.
 

Artstu

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Aug 2, 2009
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I'm confused as to why someone would buy a bicycle and then want it to go up a 40% hill without pedalling? Are you sure it's that steep? and what's wrong with pedalling as well?
 

carbolts

Finding my (electric) wheels
Nov 2, 2014
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Sorry no I dont mind pedeling aswell, I was just wondering if the motor was capable of pushing me and the bike up that hill on its own.
I may have over estimated the steepness of the hill. It is very steep but its probably more like 30-40%
 

JohnCade

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May 16, 2014
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Trex probably had it right. No hill is 40% it's impossible. It's probably more like 20% or under. That is a very steep hill and there aren't many that steep.
 

danielrlee

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May 27, 2012
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Trex probably had it right. No hill is 40% it's impossible. It's probably more like 20% or under. That is a very steep hill and there aren't many that steep.
Most definitely not impossible. I live in Wiltshire and can think of a few roads near me with 40% gradients for short distances.

I prefer hub motors myself, but if I had to do a lot of climbing, I'd take trex's advice and get a mid-drive.
 

trex

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May 15, 2011
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Do you think the 350watt woosh bike kit would be able to get me up a 22% elevation?
CD kit: just about enough power without, albeit very slowly, 5mph - I think you still need a little bit of pedalling, it's more confortable when climbing steep hills.
BPM kit: a bit under power, needs hard pedalling but easy peasy for the rest of the trip.
 

carbolts

Finding my (electric) wheels
Nov 2, 2014
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just about enough power without, albeit very slowly, 5mph - I think you still need a little bit of pedalling, it's more confortable when climbing steep hills.
That great news. Although it might be nice to get a more powerfull kit as I can do that hill off road.
Thank you very much for your help.
John
 

JohnCade

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May 16, 2014
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Most definitely not impossible. I live in Wiltshire and can think of a few roads near me with 40% gradients for short distances.

I prefer hub motors myself, but if I had to do a lot of climbing, I'd take trex's advice and get a mid-drive.
I think the steepest hill in the UK has a sign that claims 40% but no one believes it. It also says it's not suitable for traffic. There are a couple in the Lake District that are 30% for short sections. 40% is 1 in 2.5 so around 21 degrees. Hard to walk up.

In practise hills start getting steep around 10% or so.
 

RobF

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Sep 22, 2012
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Here's pic from The Guardian of Rosedale, which does look fairly sharp:
Rosedale-Chimney-Bank-in--003.jpg
 
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danielrlee

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May 27, 2012
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I think the steepest hill in the UK has a sign that claims 40% but no one believes it. It also says it's not suitable for traffic. There are a couple in the Lake District that are 30% for short sections. 40% is 1 in 2.5 so around 21 degrees. Hard to walk up.

In practise hills start getting steep around 10% or so.
I'd imagine that published gradients are averages of the hills in question and you'd find sections with steeper gradients than the figure quoted.
 

Artstu

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Aug 2, 2009
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Worth noting that the crank-drive kits mentioned don't like gear-changes under load.
 

RobF

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Sep 22, 2012
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Worth noting that the crank-drive kits mentioned don't like gear-changes under load.
True, although if you were tackling something like Hardknott, changing part way up on any bike - powered or not - would not be a good idea.

Defo a case for getting into first gear as soon as the climb ramps up and staying there.
 

carbolts

Finding my (electric) wheels
Nov 2, 2014
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So Im now looking at buying the BBS02 36V 25A from wooshbikes. Im I right in saying that I would have to lose 2 of my chain rings, so losing most of my gears? Also Is it easy to derestrict the wooshbike motor?
 

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