Possible downside to speed pedelec / class 3 / 28 MPH ?

[bruceT]

In one of Cort's videos he comments that over 20 MPH the wind resistance takes an exponential toll on battery life - must be due to the fact that air drag increases with the cube of the speed. check out this graph.. https://goo.gl/PcsZKQ

I just got my first chance to ride the giant Quick E. I'm 6' 3" and weigh 215-220. On a flat road 1/4 -1/2 mile stretch, I was able to hit 22 max - in top gear and peddling hard - about the same speed I do during a mile or two sprint on my road bike / flat road. My main interest in an ebike is for riding in the white mountains on a combination of tarmac and dirt roads - hoping to flatten the hills a bit / extend my range. The bike I'm most interested in is the Giant tough road GX E+ - one of the few gravel ebikes I've seen. The main downside I see with this bike that it is limited to 20 MPH (I like speed), but given the above graph, my size, and my experience with the quick E perhaps the energy saving and wind resistance may make the 20 MPH limit a good thing - last thing I want is to run out of battery with a mile long 10%+ climb on a heavy bike. Should still go like hell on the downhills - maybe extra ebike weight is a positive when going downhill

 

[rich c]

I've mentioned before, it's not that I want to ride assisted AT 28mph, it's more about liking to ride assisted in the 20-22mph range. Above that, the wind resistance is huge! Many of the 20 mph bikes fade at 19, some pretty abruptly. I rode a Specialized bike that felt like it was hunting for assisted between 19-20. It was very annoying to feel the motor come off and on. It felt like you would have to watch the speedometer and stay below 19 to not deal with it.

 

[christob]

I certainly see a huge difference in battery duration if I spend much time over 20mph, or when there is anything more than a modest breeze blowing against me. I was unable to complete a 17 mile trip (paved trail) in heavy winds without the battery dying at 16 miles -- while on another day, I made a 36 mile trip (paved trail) and got home with 3 bars left... (for that trip I deliberately stayed in Level 1 as much as possible, using 2 or 3 or 4 for more challenging inclines -- there was no strong wind that day, so I didn't have to use 2 or 3 to help overcome wind on flats or shallow inclines -- and I made sure to revert to 1 as soon as possible every time. Other than speeding down inclines with gravity to help, I basically kept my ride in the 13 - 18 mph.

 

[elyhim]

People bash the Bosch as resistance but imo there is no issues within the assist range wind, no wind or hills. Cadence is what matters.

 

[bob armani]

I certainly see a huge difference in battery duration if I spend much time over 20mph, or when there is anything more than a modest breeze blowing against me. I was unable to complete a 17 mile trip (paved trail) in heavy winds without the battery dying at 16 miles -- while on another day, I made a 36 mile trip (paved trail) and got home with 3 bars left... (for that trip I deliberately stayed in Level 1 as much as possible, using 2 or 3 or 4 for more challenging inclines -- there was no strong wind that day, so I didn't have to use 2 or 3 to help overcome wind on flats or shallow inclines -- and I made sure to revert to 1 as soon as possible every time. Other than speeding down inclines with gravity to help, I basically kept my ride in the 13 - 18 mph.

I ride in just about the highest level of assist 99% of the time on a rear hub motor and get about the same amount of battery life regardless of the wind on flats (give or take a few miles). Even on startups I do not bother to change levels of PAS, and it seems to work great for my riding style. I do not change gears often and stay in the highest gear most of the time. I only change gears on 5-8% plus inclines, and even then, I can maintain 16-18 mph. I am no pro biker by any means, just the average 3-4 day a week rider during temps above 50-60 degrees fahrenheit.
When I get a mid-driven E-bike, I am sure that will be a different experience IMHO.

 

[JoePah]

I would love the option of hitting 28 mph on an ebike... Sure, your range will take a severe hit, but so what? If you need more range, just reduce the pedal assist level, or don't pedal as fast, and keep your speed around 20 mph.

 

[bruceT]

The reason for the original question is that Giant chose to limit the tough road-e to 20 Mph while the road-e and the quick-e are both 28 Mph - same motor and battery in all 3. It's geared differently that the other two – 42x11 is more than enough to exceed 28.

 

[BobG]

There is a safety downside to riding an e-bike at 28 mph. Motorists entering from side roads where they must yield may mis-judge your speed and pull out in front of you. Many may not be expecting a recreational cyclist to be approaching at 28 mph.

 

[JoePah]

The reason for the original question is that Giant chose to limit the tough road-e to 20 Mph while the road-e and the quick-e are both 28 Mph - same motor and battery in all 3. It's geared differently that the other two – 42x11 is more than enough to exceed 28.

OIC. Giant must figure that a trail bike doesn’t need to reach 28 mph. That’s actually pretty common

I’ve been looking at the Evo motion trail bikes and they are all linked to 20 mph

Power just cuts out at 20 mph I guess

 

[Bruce Arnold]

In one of Cort's videos he comments that over 20 MPH the wind resistance takes an exponential toll on battery life - must be due to the fact that air drag increases with the cube of the speed. check out this graph.. https://goo.gl/PcsZKQ

I just got my first chance to ride the giant Quick E. I'm 6' 3" and weigh 215-220. On a flat road 1/4 -1/2 mile stretch, I was able to hit 22 max - in top gear and peddling hard - about the same speed I do during a mile or two sprint on my road bike / flat road. My main interest in an ebike is for riding in the white mountains on a combination of tarmac and dirt roads - hoping to flatten the hills a bit / extend my range. The bike I'm most interested in is the Giant tough road GX E+ - one of the few gravel ebikes I've seen. The main downside I see with this bike that it is limited to 20 MPH (I like speed), but given the above graph, my size, and my experience with the quick E perhaps the energy saving and wind resistance may make the 20 MPH limit a good thing - last thing I want is to run out of battery with a mile long 10%+ climb on a heavy bike. Should still go like hell on the downhills - maybe extra ebike weight is a positive when going downhill

That top end of 22 mph puzzles me. The Quick E is advertised as a 28 mph bike. Flat road, high gear, pedalling hard - strange.

It's not the your size and it's not wind resistance, although those are important factors. But today I maintained an easy 23-25 mph, 2nd level of assist (or "Level 1" as we call it in Juiced Bikes-land - the lowest level is "Eco"), on a flat road, in 8th gear, pedalling moderately. Kicking it up to Level 3 to beat a light, I momentarily clocked 30 mph, pedalling hard. I weigh about 60 lbs more than you.

I'm not sure how to account for this. Were you in the lowest level of assist? Tires underinflated? Battling a headwind?

I'm trying to avoid saying the Quick E might be underpowered (and over-advertised), never having ridden one, but all other things being equal, I've gotta wonder.

Look at the Juiced Bikes RipCurrent S. Ought to be good on gravel roads, and I guarantee you'll get a fast bike. Good price too.

 

[Chris Hammond]

You are correct about the exponential impact of wind resistance as speed grows. There are plenty of Class 3 bikes that can maintain 28 mph on flat terrain with moderate pedal input. Most owners report power usage of ~ 30 watts per mile at that speed. Thus if you have a 15 mile one way commute, you are essentially going to deplete a 500 Wh battery.
If you want to ride fast and go very far, you need a big battery. Obviously there are things you can do to improve your aero but there are limits.
I'm still commuting on my road bike, and on flat terrain with no wind I can maintain 20 mph for as long as I want. If I bought an ebike and only achieved 22 I'd be downright pissed.
One of the problems mid-drives have as commuters is you use the highest gears, you actually decrease the torque available at the rear wheel. This means you are more likely to experience limited power at higher speeds.
Hub drives obviously don't experience this loss in torque because they are powering the wheel directly. The gear you are pedaling makes no difference to the torque available from the motor. (Hugely impacts torque available from the rider).

For these reasons and many others, I ordered the same bike Bruce has, the Juiced CrossCurrent S. I also ordered it with the 52V 21Ah battery. Like you I enjoy riding fast, and my commute is 30 miles each way.

The most important thing you can do in buying a bike is to get the biggest battery you can reasonably afford. If you sacrifice on it you'll likely regret it.

 

[Ken M]

I would love the option of hitting 28 mph on an ebike... Sure, your range will take a severe hit, but so what? If you need more range, just reduce the pedal assist level, or don't pedal as fast, and keep your speed around 20 mph.

That is great response. To some commuters reducing commute times with higher average speeds more than covers the extra expense of shorter battery range. I just want my battery to get me to work and back (25 miles) at the fastest speed I feel safe at (usually like cruising around 25-28mph when I'm on the street and I'm no speed demon. I'm 57 and just started riding the eBike after 20 years of not riding and I enjoy the lifestyle of not getting in the car every morning. Rode most days in the winter in Denver Colorado and I was surprised to find out how comfortable it is to ride in the winter (you warm up quickly).

I have a saying ... "if you don't want to ride faster than 20mph....walk." I don't get this fear factor everyone talks about when riding over 20mph. I was crusing at 33mph for about a 1/4 mile the other day and I felt totally safe...even safer as my differential to the car speeds was reduced (no one talks about that factor).

 

[Ken M]

You are correct about the exponential impact of wind resistance as speed grows. There are plenty of Class 3 bikes that can maintain 28 mph on flat terrain with moderate pedal input. Most owners report power usage of ~ 30 watts per mile at that speed. Thus if you have a 15 mile one way commute, you are essentially going to deplete a 500 Wh battery.
If you want to ride fast and go very far, you need a big battery. Obviously there are things you can do to improve your aero but there are limits.
I'm still commuting on my road bike, and on flat terrain with no wind I can maintain 20 mph for as long as I want. If I bought an ebike and only achieved 22 I'd be downright pissed.
One of the problems mid-drives have as commuters is you use the highest gears, you actually decrease the torque available at the rear wheel. This means you are more likely to experience limited power at higher speeds.
Hub drives obviously don't experience this loss in torque because they are powering the wheel directly. The gear you are pedaling makes no difference to the torque available from the motor. (Hugely impacts torque available from the rider).

For these reasons and many others, I ordered the same bike Bruce has, the Juiced CrossCurrent S. I also ordered it with the 52V 21Ah battery. Like you I enjoy riding fast, and my commute is 30 miles each way.

The most important thing you can do in buying a bike is to get the biggest battery you can reasonably afford. If you sacrifice on it you'll likely regret it.

I've been writing to various forum on the point you make about the gear ratio problem with mid-drives. I have plenty of experience verifying exactly what you mentioned. If I'm on my "unlocked" Haibike with a Yamaha PW motor trying to ride faster than 20mph I'm on a 44-48T front sprocket and an 11T rear so 75% of the motor torque is lost via the gear ratio. My Haibike with the Bosch does better because the front chain ring is 16T and spins 2.5X cadence so much more of the motor torque reaches the rear wheel at higher speeds. Yamaha has a great reputation for climbing and Bosch has a better reputation for assisting at higher sustained speeds. But the best commute bike I have is a PIM Archer with a 750W gearless hub motor. I can ride fairly easily at 25mph (assist cuts off due to Kv limit of the motor) and it's the bike I do most of my commuting on. I can cut about 5-10 minutes each way on my 13 mile work commute. Simple math if you consider your time worth anything.

 

[JRA]

Hills, headwinds and as Court says speeds above 20 all are potential energy drains motor assist or not. To me the only reason I have e assist on my road bikes is to overcome them enough so that my energy input remains constant but my overall average speed is increased. Although range is more important to me than speed, there can be a happy medium.

My solution was to build what I thought would meet my needs, I also ride lots of gravè and single track lite, utilizing a solid platform and proven tech. The end result has been very satisfying. I have posted threads on here describing how this bike is set up. It doesn't look as sleek as the bikes coming out from the manufacturers but its an open source build that allows me to easily replace, repair and upgrade the bike myself.

As mentioned speed kills ah's. I did a speed run on a loop from my place that is flat 2 lane pavement, light wind.



A more typical pleasure ride with hills, headwinds, stop and go etc.



Maybe it's just me and my bike setup but after keeping track of my wh/mi use with average speeds over 20 the past year I have found that the avg. spd. is often very close to the wh/mi.

This was my commute last summer. Mix of two lane country road, 4 lane with big shoulder and 7 miles of surface streets in the city (PDX) I have a 10.5ah battery and could count on recharging at work.



It takes me 45 minutes to get there by car btw.

 

[JoePah]

Hills, headwinds and as Court says speeds above 20 all are potential energy drains motor assist or not. To me the only reason I have e assist on my road bikes is to overcome them enough so that my energy input remains constant but my overall average speed is increased. Although range is more important to me than speed, there can be a happy medium.

My solution was to build what I thought would meet my needs, I also ride lots of gravè and single track lite, utilizing a solid platform and proven tech. The end result has been very satisfying. I have posted threads on here describing how this bike is set up. It doesn't look as sleek as the bikes coming out from the manufacturers but its an open source build that allows me to easily replace, repair and upgrade the bike myself.

View attachment 20985

As mentioned speed kills ah's. I did a speed run on a loop from my place that is flat 2 lane pavement, light wind.

View attachment 21012

A more typical pleasure ride with hills, headwinds, stop and go etc.

View attachment 21010

Maybe it's just me and my bike setup but after keeping track of my wh/mi use with average speeds over 20 the past year I have found that the avg. spd. is often very close to the wh/mi.

This was my commute last summer. Mix of two lane country road, 4 lane with big shoulder and 7 miles of surface streets in the city (PDX) I have a 10.5ah battery and could count on recharging at work.

View attachment 21011

It takes me 45 minutes to get there by car btw.

Good info dude!

That is a very high average speed, even if you don't have stop signs or dogs...

 

[bruceT]

That top end of 22 mph puzzles me. The Quick E is advertised as a 28 mph bike. Flat road, high gear, pedalling hard - strange.

It's not the your size and it's not wind resistance, although those are important factors. But today I maintained an easy 23-25 mph, 2nd level of assist (or "Level 1" as we call it in Juiced Bikes-land - the lowest level is "Eco"), on a flat road, in 8th gear, pedalling moderately. Kicking it up to Level 3 to beat a light, I momentarily clocked 30 mph, pedalling hard. I weigh about 60 lbs more than you.

I'm not sure how to account for this. Were you in the lowest level of assist? Tires underinflated? Battling a headwind?

I'm trying to avoid saying the Quick E might be underpowered (and over-advertised), never having ridden one, but all other things being equal, I've gotta wonder.

Look at the Juiced Bikes RipCurrent S. Ought to be good on gravel roads, and I guarantee you'll get a fast bike. Good price too.

A couple of things that may have effected it..

• The only place I could demo the bike was at a giant dealer in Boston / Fenway - lots of traffic but I tried my speed run on a quiet side street over a city block and a couple of stretches on a parkway - but always had to be mindful of traffic so perhaps I was backing off.
• The bike was a large and I need an XL - leg extension was poor
• I typically ride clipless peddles and didn't feel comfortable getting out of the saddle with flats and running shoes - with clipless I also pull on the upstroke
• I didn't use the top gear since the front derailleur was rubbing
• Didn't want to break a 3k bike I had no intention of buying - just demo

 

[bruceT]

OIC. Giant must figure that a trail bike doesn’t need to reach 28 mph. That’s actually pretty common

I’ve been looking at the Evo motion trail bikes and they are all linked to 20 mph

Power just cuts out at 20 mph I guess

I can understand the limit on a e-mountain bike - in part to keep the trail in better shape / safer for less experienced with too much speed. The thing that bugs me about this bike is the only thing trail about it is the fact it has slightly knobby tires. It's called a tough ROAD - the geometry, drop bars, lack of suspension, etc say road bike with fat tires (700x50c) - that's what gravel bikes are all about - would not work for anything resembling single track / technical riding. While the tires are fatter than the road-e, they are about the same size as the quick-e. There are aftermarket hacks to get around it or I could buy the rode-e and swap out the drive train for 1X and put bigger tires on it - but that seems like a waste since the tough road has everything I want - except the limit. Perhaps a mute point for me since I'm mostly looking for help climbing hills and doubt I will see 20 MPH going uphill. I have very few flat road to ride on at my home in the mountains.

 

[Mr. Coffee]

My $0.02:

The sweet spot for me seems to be around 15mph. I can ride at that speed comfortably for 3-4 hours at modest levels of pedal assist and don't need to worry much about the battery (yesterday I went for a 45 mile ride with a fair amount of elevation gain and loss and still had 1 bar at the end), So that is what works for me.

At speeds above 18mph most of the energy and effort is going into displacing air, not moving me along. So I reserve the high speeds for outrunning weather, getting through scary sections of road, and for when I am just plain whipped.

 

[Bruce Arnold]

I have a saying ... "if you don't want to ride faster than 20mph....walk."

OK, so the elderly, people with health issues, parents with kids in child seats, maybe people hauling a trailer full of groceries -- should stay off bikes?

I'll just stop there.

 

[Chris Hammond]

Maybe it's just me and my bike setup but after keeping track of my wh/mi use with average speeds over 20 the past year I have found that the avg. spd. is often very close to the wh/mi.

Very interesting observation. I recently bought a newer car (Chevy Cruze Eco w/ manual trans). My Avg MPG and average speed is nearly identical in the ~5000 miles I've put on it at ~ 37.5.