Electric bike question please

I ride a road bike usually twice a week, usually 30-40 miles each. I used to ride (not average) about 15-16 mph. Due to a few health problems + hitting my 70th birthday I'm down to 13-14 mph and I'm terrible on hills (Florida hills). I'm considering getting an electric assist for my road bike by replacing the rear wheel with the assist, the battery would go in my water bottle holder. I would like it to assist me to get back to my 15-16 speed or close to it.

Opinions please. Would this be a doable solution?

Thanks in advance... Bob

On 1/23/2018 2:18 PM, Bob Newman wrote:
I ride a road bike usually twice a week, usually 30-40 miles each. I used to ride (not average) about 15-16 mph. Due to a few health problems + hitting my 70th birthday I'm down to 13-14 mph and I'm terrible on hills (Florida hills). I'm considering getting an electric assist for my road bike by replacing the rear wheel with the assist, the battery would go in my water bottle holder. I would like it to assist me to get back to my 15-16 speed or close to it.

Opinions please. Would this be a doable solution?

Thanks in advance... Bob


I can't directly address the tech aspects, except to note that I /think/
rear-wheel electric retrofits are indeed on the market.

What I /can/ say is that the wife really likes her new electric-assist
bike (Trek "Verve +"). It's a ground-up "pedelec" with motor mounted in
a bulging casing in the bottom bracket area. "Pedelec" means it assists
in proportion to the effort of the rider. There is no throttle, and no
pedaling means no assist.

She just gets on it and rides, and she has no trouble staying with me
(on my non-assisted bike) for rides of 20+ miles, even though she has
ridden very little in the last five years. On one ride she set her bike
on "sport" mode and had no trouble holding my wheel when I was on my
carbon-fiber wonderbike. In "sport" mode the motor supposedly
contributes 175% of the power that the rider is contributing.

Her model is upright with a Bosch motor. The Bosch is pretty much
silent, unlike the Shimano-motor model we test-rode, which made a mild
whiny whirring sound. Range in "sport" mode looks to be around 40
miles; in "tour" mode (doubles riders' power output), closer to 60
miles. YMMV.

I'm only pushing 60, but I admit to temptation. There are drop-bar
sporty pedelecs from Trek and Giant. Maybe in another 10 years.

So to address your question, I know that an electric assist can make a
big difference, and it looks ideally suited to your situation. Whether
a retrofit would be as nice as a purpose-built pedelec I can't say.

Mark J.

Bob Newman wrote:
I ride a road bike usually twice a week, usually 30-40 miles each. I
used to ride (not average) about 15-16 mph. Due to a few health problems
+ hitting my 70th birthday I'm down to 13-14 mph and I'm terrible on
hills (Florida hills). I'm considering getting an electric assist for my
road bike by replacing the rear wheel with the assist, the battery would
go in my water bottle holder. I would like it to assist me to get back
to my 15-16 speed or close to it.

Opinions please. Would this be a doable solution?

Thanks in advance... Bob


I suspect you would want a battery larger than a water bottle, but I'll
admit to not doing the math.

Ralph Barone wrote:
Bob Newman wrote:
I ride a road bike usually twice a week, usually 30-40 miles each. I
used to ride (not average) about 15-16 mph. Due to a few health problems
+ hitting my 70th birthday I'm down to 13-14 mph and I'm terrible on
hills (Florida hills). I'm considering getting an electric assist for my
road bike by replacing the rear wheel with the assist, the battery would
go in my water bottle holder. I would like it to assist me to get back
to my 15-16 speed or close to it.

Opinions please. Would this be a doable solution?

Thanks in advance... Bob


I suspect you would want a battery larger than a water bottle, but I'll
admit to not doing the math.

OK, I'll give this math thing a shot. Li-ion batteries have a volumetric
efficiency at the low end of approx 300 W-hr/litre. If you need a 50 W
average boost (and 50 W is a pretty mild boost) for your 2 1/2 hr ride,
that's 125 W-hr, so maybe a half litre of battery. Surprise! That might
actually fit in a water bottle holder. This doesn't take any system
inefficiencies into account, but I pulled a volumetric efficiency from the
low end, so I shouldn't be too far from the truth here.

On Tuesday, January 23, 2018 at 8:57:33 PM UTC-5, Ralph Barone wrote:
Ralph Barone wrote:
Bob Newman wrote:
I ride a road bike usually twice a week, usually 30-40 miles each. I
used to ride (not average) about 15-16 mph. Due to a few health problems
+ hitting my 70th birthday I'm down to 13-14 mph and I'm terrible on
hills (Florida hills). I'm considering getting an electric assist for my
road bike by replacing the rear wheel with the assist, the battery would
go in my water bottle holder. I would like it to assist me to get back
to my 15-16 speed or close to it.

Opinions please. Would this be a doable solution?

Thanks in advance... Bob


I suspect you would want a battery larger than a water bottle, but I'll
admit to not doing the math.

OK, I'll give this math thing a shot. Li-ion batteries have a volumetric
efficiency at the low end of approx 300 W-hr/litre. If you need a 50 W
average boost (and 50 W is a pretty mild boost) for your 2 1/2 hr ride,
that's 125 W-hr, so maybe a half litre of battery. Surprise! That might
actually fit in a water bottle holder. This doesn't take any system
inefficiencies into account, but I pulled a volumetric efficiency from the
low end, so I shouldn't be too far from the truth here.

The thing that defeats trying to figure out how long the battery will last is that I will not be using the battery exclusively. I plan on pedaling with the same intensity that I do now. Therefore the battery should last much longer than if it was doing all of the work. I am only asking it to take me from 13 MPH to 15 MPH. Does anyone have any actual experience in using an ebike in this matter? How did it go.

Thanks... Bob

Bob Newman wrote:
On Tuesday, January 23, 2018 at 8:57:33 PM UTC-5, Ralph Barone wrote:
Ralph Barone wrote:
Bob Newman wrote:
I ride a road bike usually twice a week, usually 30-40 miles each. I
used to ride (not average) about 15-16 mph. Due to a few health problems
+ hitting my 70th birthday I'm down to 13-14 mph and I'm terrible on
hills (Florida hills). I'm considering getting an electric assist for my
road bike by replacing the rear wheel with the assist, the battery would
go in my water bottle holder. I would like it to assist me to get back
to my 15-16 speed or close to it.

Opinions please. Would this be a doable solution?

Thanks in advance... Bob


I suspect you would want a battery larger than a water bottle, but I'll
admit to not doing the math.

OK, I'll give this math thing a shot. Li-ion batteries have a volumetric
efficiency at the low end of approx 300 W-hr/litre. If you need a 50 W
average boost (and 50 W is a pretty mild boost) for your 2 1/2 hr ride,
that's 125 W-hr, so maybe a half litre of battery. Surprise! That might
actually fit in a water bottle holder. This doesn't take any system
inefficiencies into account, but I pulled a volumetric efficiency from the
low end, so I shouldn't be too far from the truth here.

The thing that defeats trying to figure out how long the battery will
last is that I will not be using the battery exclusively. I plan on
pedaling with the same intensity that I do now. Therefore the battery
should last much longer than if it was doing all of the work. I am only
asking it to take me from 13 MPH to 15 MPH. Does anyone have any actual
experience in using an ebike in this matter? How did it go.

Thanks... Bob


According to http://bikecalculator.com , an extra 40 W should get you from
13 to 15 mph, although you're welcome to punch your own data in there and
get a more accurate number.

On Tuesday, January 23, 2018 at 10:37:50 PM UTC-5, Ralph Barone wrote:
Bob Newman wrote:
On Tuesday, January 23, 2018 at 8:57:33 PM UTC-5, Ralph Barone wrote:
Ralph Barone wrote:
Bob Newman wrote:
I ride a road bike usually twice a week, usually 30-40 miles each. I
used to ride (not average) about 15-16 mph. Due to a few health problems
+ hitting my 70th birthday I'm down to 13-14 mph and I'm terrible on
hills (Florida hills). I'm considering getting an electric assist for my
road bike by replacing the rear wheel with the assist, the battery would
go in my water bottle holder. I would like it to assist me to get back
to my 15-16 speed or close to it.

Opinions please. Would this be a doable solution?

Thanks in advance... Bob


I suspect you would want a battery larger than a water bottle, but I'll
admit to not doing the math.

OK, I'll give this math thing a shot. Li-ion batteries have a volumetric
efficiency at the low end of approx 300 W-hr/litre. If you need a 50 W
average boost (and 50 W is a pretty mild boost) for your 2 1/2 hr ride,
that's 125 W-hr, so maybe a half litre of battery. Surprise! That might
actually fit in a water bottle holder. This doesn't take any system
inefficiencies into account, but I pulled a volumetric efficiency from the
low end, so I shouldn't be too far from the truth here.

The thing that defeats trying to figure out how long the battery will
last is that I will not be using the battery exclusively. I plan on
pedaling with the same intensity that I do now. Therefore the battery
should last much longer than if it was doing all of the work. I am only
asking it to take me from 13 MPH to 15 MPH. Does anyone have any actual
experience in using an ebike in this matter? How did it go.

Thanks... Bob


According to http://bikecalculator.com , an extra 40 W should get you from
13 to 15 mph, although you're welcome to punch your own data in there and
get a more accurate number.

Thanks. I appreciate your help... Bob

Rarely see the same electric twice ...

On Tuesday, January 23, 2018 at 11:18:40 PM UTC+1, Bob Newman wrote:
I ride a road bike usually twice a week, usually 30-40 miles each. I used to ride (not average) about 15-16 mph. Due to a few health problems + hitting my 70th birthday I'm down to 13-14 mph and I'm terrible on hills (Florida hills). I'm considering getting an electric assist for my road bike by replacing the rear wheel with the assist, the battery would go in my water bottle holder. I would like it to assist me to get back to my 15-16 speed or close to it.

Opinions please. Would this be a doable solution?

Thanks in advance... Bob

Beside that you increase the weight of your nice road bike with 3-4 kg what is the importance of adding an 'artificial' 2 mph to your average speed at your age? Just out of curiosity.

Lou

On Wednesday, January 24, 2018 at 10:55:06 AM UTC-8, wrote:
On Tuesday, January 23, 2018 at 11:18:40 PM UTC+1, Bob Newman wrote:
I ride a road bike usually twice a week, usually 30-40 miles each. I used to ride (not average) about 15-16 mph. Due to a few health problems + hitting my 70th birthday I'm down to 13-14 mph and I'm terrible on hills (Florida hills). I'm considering getting an electric assist for my road bike by replacing the rear wheel with the assist, the battery would go in my water bottle holder. I would like it to assist me to get back to my 15-16 speed or close to it.

Opinions please. Would this be a doable solution?

Thanks in advance... Bob

Beside that you increase the weight of your nice road bike with 3-4 kg what is the importance of adding an 'artificial' 2 mph to your average speed at your age? Just out of curiosity.

Typical question from a young guy! I'm getting one of these: http://www.pinarello.com/en/bike-2018/e-bike/nytro

It looks super-cool and has a peak assist of 400 watts. Added to my own output, that would give me like 450 watts! I'd be a superstar!

I sometimes ride in a group with a 70 year old national quality racer who is fast -- for a while. He's also really strategic. When we do loops through the country, he'll skip a hilly segment and cut the loop to save energy. If you put him on one of those racing e-bikes, he'd probably kick our asses.. It's fun to still go fast when you get old. I experience that only when descending.


-- Jay Beattie.