Optimizing Specialized Creo Expert SL with 1.1 motor for 60 miles at 25mph

[BikeMike]

Hi,

I sent the following email to Specialized Care today. Perhaps, your answer will prove more informative?

I own a 2015 Specialized Diverge (mechanical bike). I live in Denver. I am a strong rider. I generally
ride about 5,000 miles per year. I weigh 225 pounds. I have generated over
800 watts on a stationary bike. I do not have a power meter, so I do not
know how much power I can sustain over 70 miles. I am a software engineer,
so precise calculations are important to me.

The main reason for considering a Creo Expert is to ride 70 miles from
Denver to Fort Collins as fast as possible.

I have a mechanical mountain bike with a single chainring. I start to spin out of
gears on my mountain bike at higher speeds. I do not like the single chain
ring efficiency at speeds over 25mph.

I always use the big chainring on my Specialized Diverge for 25mph speeds. I would like
the Creo Expert chain to be as straight as possible at 25mph. I expect to
ride for miles, on country roads, in the same gear at 25mph. My typical
cadence is 95 RPM.

1. Which chainring/cassette combination is optimal for 25mph battery
consumption?

2. How much aerodynamic overhead does the Creo frame incur over the
Diverge?
- The bottom bracket is wider. I suppose the downtube is wider to
accommodate the battery?

3. How much power is consumed by the eBike to overcome it's weight,
aerodynamics, motor resistance, etc...?
- I suppose the Eco setting (30%) is needed to offset the overhead?

4. If I rode the bike with and without electric power, how would I
calculate the minimum motor power and battery capacity I would need to ride
70 miles at 25mph?

5. Is the Di2 shifter synchronized with the motor to suspend power when
shifting gears?

I understand 170 watts are generally required to reach 20mph speeds. 300
watts are generally required to reach 25mph speeds. The SL 1.1 is rated at
240 watts. The maximum sustained speed of the motor should be between 20 to
25mph. 28mph only makes sense to me, when I supply the underlying speed.

1. What speed do I need to pedal the Creo Expert at without power, for
the bike to achieve 28mph with power?

Attached please see the ride I am most concerned about optimizing battery power at 25mph. The section from Westminster to Boyd Lake State Park.

.

 

[JRA]

Looks like the possibility of stop signs and traffic lights so factor those into your equation. Stops/starts to speed can eat wh's more than maintaining an average speed.

From my experience unless you are a Cat1 rider to begin with you would need a more powerful e system with a much bigger battery to achieve your goal.

 

[BikeMike]

Do you happen to know how accurately Zwift simulates motor performance and battery consumption?

 

[BikeMike]

You answered the question I was alluding to. I thought the solution might be the most efficient drivetrain that is best matched to the motor.

I could list the start/stops, if that helps estimation.

Would the second 160wh battery fully compensate?

 

[JRA]

Wh/mi usage is the best gauge of desired mileage attained at the speed you desire to go. This can fluctuate due to desired speed, terrain, stops/starts, elevation gain, aerodynamics (which at 25mph definitely becomes a negative factor) and of course rider average watt input.

The reason that you see high average speeds in bike racing is due to closed courses and the peloton effect. It is very hard to achieve those averages solo on open routes to begin with. An eBike can help to achieve a higher than your normal average speed. If you can average 20mph on the same route with your regular bike it might be possible with a Creo but 480wh of battery would require about 10wh/mi use which is pretty low.

Best thing I can say is to test ride a Creo if you can and see what you come up with trying to keep your 25mph average before you buy. You can crunch numbers all day but real world seat of the pants data is the easiest way to figure out what system will work best for your needs.

 

[BikeMike]

I am in the 20 to 25 mph range on ideal flat conditions. Wind speed affects me the most. The north winds can be brutal.

According to the Specialized website, almost no Creo inventory exists. My understanding is you need to put down a deposit, without riding the bike beforehand.

Thanks for the 10 wh/mi rule of thumb. Specialized makes this very vague claim:

240 watts up to 28 miles per hour, eco mode. Does this estimate maker rough sense to you? I have been reading for hours, but finding few details.

• If the battery lasts one hour, then the figure is about 8.5 wh/mi.

I have found a graph about power vs. cadence.

I will contact this user. He has published some data ( #182 ) on this site.

 

[BikeMike]

Looks like the possibility of stop signs and traffic lights so factor those into your equation. Stops/starts to speed can eat wh's more than maintaining an average speed.

From my experience unless you are a Cat1 rider to begin with you would need a more powerful e system with a much bigger battery to achieve your goal.

The real value of the eBike probably lies in the acceleration assistance from stops, rather than speed bump over 20mph. I have tried over a dozen eBikes, but never found a compelling advantage over my bikes. I compared the eBikes by riding them with and without power. Riding Without power tells me most about eBikes.

 

[Nubnub]

How long does it take to do this ride now on your current setup?

One other way of looking at it is that you want to complete the ride in about 2 hrs. With either 320 or 480 (with extender) Wh, that gives you 160 or 240 Wh of assist per hour. Keep in mind that as the battery depletes the voltage lowers and the motor power available will lower. But for round numbers 150 Wh/hr is a good amount for an SL bike on the flats. As you and JRA noted, wind resistance will be the big factor at the speeds you want to go.

For reference, if the Creo's SL eco mode is set to 30 support and 30 peak power, it will be using much less than 150 Wh/hr. You could also use Smart Control to set your ride parameters so that you can maximize battery usage. It should give you considerably more assistance than just ECO tho I'm not sure it can really account for headwinds in its calculations.

As JRA points out, there are so many variables that the best thing is to try to find one to test out. If the Creo SL is like the Vado it will have power/cadence sensors so if you do find one to test - bring a bike computer so you can see your power output and how the various assist levels affect it. Play around with the tuning levels for support and peak power.

 

[BikeMike]

How long does it take to do this ride now on your current setup?

One other way of looking at it is that you want to complete the ride in about 2 hrs. With either 320 or 480 (with extender) Wh, that gives you 160 or 240 Wh of assist per hour. Keep in mind that as the battery depletes the voltage lowers and the motor power available will lower. But for round numbers 150 Wh/hr is a good amount for an SL bike on the flats. As you and JRA noted, wind resistance will be the big factor at the speeds you want to go.

For reference, if the Creo's SL eco mode is set to 30 support and 30 peak power, it will be using much less than 150 Wh/hr. You could also use Smart Control to set your ride parameters so that you can maximize battery usage. It should give you considerably more assistance than just ECO tho I'm not sure it can really account for headwinds in its calculations.

As JRA points out, there are so many variables that the best thing is to try to find one to test out. If the Creo SL is like the Vado it will have power/cadence sensors so if you do find one to test - bring a bike computer so you can see your power output and how the various assist levels affect it. Play around with the tuning levels for support and peak power.

I have not ridden the route, yet. I plan to ride there on a regular basis. I live in the LoDo district of Denver, near Union Station RTD. I want to leave Denver due to the high covid19 infection rate. I have not owned a car for years. I get around Denver just fine by bike. My mother lives 15 miles up the Platte River. A bike suffices. I ride about 20 to 25mph along the Platte River. I do not pay close attention to speed statistics. I use the Garmin when something is wrong. I don't need a car. I am thinking of an eBike as a car replacement.

My understanding is a deposit is required to order a Creo Expert. I don't have the opportunity to test ride. My bikeshop has a 30-day return policy instead. My idea is use the Creo on a trainer. I would ride the Zwift route to determine how to optimize the bike.

I expect to ride part of the way without power, even with two batteries. The motor decoupling is touted as being near unnoticeable drag. My impression is the drivetrain might be the biggest inefficiency. The drivetrain ( https://www.specialized.com/us/en/turbo-creo-sl-expert/p/170238 ) is:

CASSETTE	Shimano XT, 11-speed, 11-42t
CHAIN	Shimano Ultegra
CHAINRINGS	Praxis, 46T, 110BCD

I am pretty confident that I need to replace the 46T chainring, based on my existing bikes. Possibly, also replace the cassette. I want the chainring and middle cassette gear to align so 25mph is optimized. Based on my mountain bike, the chain will probably be aligned near the 11t sprocket at 25mph. I imagine the chain will be twisted for hours with a 46/11T configuration, rather than aligned in a straight pull.

I want to record data from the Zwift route on a trainer, so I can find the optimal battery consumption. I expect to run out of battery power. I want to minimize the time spent riding without power.

 

[BikeMike]

How long does it take to do this ride now on your current setup?

One other way of looking at it is that you want to complete the ride in about 2 hrs. With either 320 or 480 (with extender) Wh, that gives you 160 or 240 Wh of assist per hour. Keep in mind that as the battery depletes the voltage lowers and the motor power available will lower. But for round numbers 150 Wh/hr is a good amount for an SL bike on the flats. As you and JRA noted, wind resistance will be the big factor at the speeds you want to go.

For reference, if the Creo's SL eco mode is set to 30 support and 30 peak power, it will be using much less than 150 Wh/hr. You could also use Smart Control to set your ride parameters so that you can maximize battery usage. It should give you considerably more assistance than just ECO tho I'm not sure it can really account for headwinds in its calculations.

As JRA points out, there are so many variables that the best thing is to try to find one to test out. If the Creo SL is like the Vado it will have power/cadence sensors so if you do find one to test - bring a bike computer so you can see your power output and how the various assist levels affect it. Play around with the tuning levels for support and peak power.
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[BikeMike]

BTW, Specialized touts the 48V battery as being more efficient. Is there substantial truth to that statement?

 

[Forkliter]

Just get a loaner/test drive of the bike from a local store and see what happens right?. You may want a tighter clustered cassette and able to give away some climbing gears. What is your weight and your FTP? Do you run a power meter? 25mph is a log of wind resistance.

 

[BikeMike]

According to the Specialized web site, they have zero to a few Creos in inventory, depending on size and configuration. My understanding is I will have to wait for my order to arrive. I will call around, but even obtaining one with a deposit can be a long delay. The Expert Creo is rarely stocked.

I weigh 225 pounds. I do not know my FTP. I have a high aerobic capacity. I ran a 25minute five mile in high school. I don't have a power meter on my bikes. I ride about 5,000 to 10,000 miles per year. I ride for fun and fitness.

 

[BikeMike]

Just get a loaner/test drive of the bike from a local store and see what happens right?. You may want a tighter clustered cassette and able to give away some climbing gears. What is your weight and your FTP? Do you run a power meter? 25mph is a log of wind resistance.

I suspect the bike motor is designed for 22mph, based on 240watts. They claim 28mph in eco mode, but a cyclist needs 300 watts at 25mph.

I just want to establish a realistic or optimal configuration. If the eBike is optimized at 22mph, I can adjust. I just want to configure the bike correctly.

 

[BikeMike]

Just get a loaner/test drive of the bike from a local store and see what happens right?. You may want a tighter clustered cassette and able to give away some climbing gears. What is your weight and your FTP? Do you run a power meter? 25mph is a log of wind resistance.

I am willing to buy a power meter, if that provides the data I need to make accurate calculations. The Creo displays both motor and rider power, so i prefer to avoid buying a power meter.

 

[Nubnub]

I wouldn't get the power meter just to determine if you want the Creo or not. If it's something you want for your bikes then sure go ahead and get it.

Looking at https://www.omnicalculator.com/sports/cycling-wattage and entering about 250 lbs for u and bike, slick tires, riding the hoods, new chain, 0 wind speed/grade and 5000 feet elevation I get: 20 mph is 179 W, 25 mph is 311 W and 28 mph is 417 W. Just a 5 mph headwind would increase these to 249, 418, 550 W. As this is the first time I've looked at this calculator I can't vouch for its accuracy, but it does support that wind speed will have a major impact on how effective the Creo's assist will help you achieve your goal.

Let's assume the above is close enough to speculate further. If you currently cruise comfortably at 20-25 mph on flat windless days - you'd appear to be producing between the 179 and 311 W. So with no wind you'd need between 238 to 106 W of assistance. If you're only going 20 mph, you're only producing 179 W and the Creo will only match that on Tubo mode (or maybe only 90% of that depending on how the 1.8 X you claim works). So on a windless day that won't get you to 28 mph. But if you are going 25 mph, then you only need the 106 W of assistance which the Creo can add - you shouldn't need full assist and it's likely even the built in battery of 320 Wh should be enough for the 53 miles. Of course as it always does, headwind can mess everything up.

 

[StmbtDave]

What I can’t wrap my mind around is why someone in your condition and ability would even consider an ebike. You’re the stereotype person that tells those of us on ebikes that we’re “cheaters”.

Dave
Loveland, CO

 

[e-levity]

... I weigh 225 pounds... I ran a 25minute five mile in high school...

Get back to your high school weight and you’ll be fine

 

[linklemming]

BTW, Specialized touts the 48V battery as being more efficient. Is there substantial truth to that statement?

100% absolutely yes, from an electrical standpoint

This is EE (Electrical Engineering) 101.

I could write an essay on this but why bother, if you want more details research it(ohms law).

 

[linklemming]

The main reason for considering a Creo Expert is to ride 70 miles from
Denver to Fort Collins as fast as possible.

That is quite a requirement, without some upper bounds, your answers will be all over the place, and likely inaccurate.

At those speeds, a hub drive will likely be the best solution, not alot of major hills for that route to need a mid-drive, winds will be your major problem.

I live north of you in louisville. When I wanted a bike to compliment my stable that had the best range and/or the best speed, the only options (at the time) were Stromers or Juiced CCX. There are now newer dual battery solutions which might suit you better but I cant provide any details.

Considering the Juiced CCX was 1/2 the price compared to a stromer, it was a no brainer. The Juiced CCX definately ticks all the correct boxes although its pretty crude (like a turbo honda civic). I have ridden stromers and LOVE them and might eventually get one.

As far as range/speed/price, the Juiced CCX seems king of the hill...and why I own one.

Tonight, I wanted to do a 'recovery ride' on my CCX since I burned myself out yesterday doing a hard MTB 20mile ride on a acoustic(non ebike). I did 30 miles averaging 19mph(which is pretty high for the conditions). I was right at 20wh/mile which is pretty typical for the speed/effort. Anything lower than 10wh/mile is a chore and 15wh/mile seems like a nice average.

By 'no means' is this a sales pitch but I am considering selling my 1.5year 3500 mile CCX. Send me an PM if interested, if not, good luck on your search.

You might want to contact ebikes of colorado in louisville, one of their mechanics commutes from denver daily and is a pretty fit cyclist. I could meet you there as well with my CCX, let me know. They also do weekly groups rides.