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

BikeMike

Active Member
I don’t see how the front derailleur would limit tire size. Prior discussions seemed to think the single chainring was a result of the large Q-Factor. Adding a second chainring would create problems in the chain alignment.

At least in the Comp line both the road and EVO models use the GRX groupset. It may have been designed for gravel bikes but it works extremely well on the road model.

I’m not sure I understand your last statement. Are you saying Specialized is marketing the Creo as a constant 28 mph bike? Being that both Class 1 and Class 3 Ebikes are pedal assist, their speed is totally dependent on the riders effort. The Class 2 Ebikes with their throttles can maintain any speed, up to their designed motor cutout, with no rider effort. I expect an extremely fit rider can maintain 28 mph fairly easily on a Creo while the rest of us mortals only hit that speed occasionally.
The front derailleur tirewidth is a standard, so manufacturers don't have to adjust the very sensitive chainstay length. Tire width is limited.

The Q factor width is also a standard, from Shimano.

The manufacturer chainring plays a role, too. You'll notice Praxis chainring and cranks, not Shimano. It's very detailed.

No, I am saying that designers make tradeoffs. They favor certain benefits and costs. For example, a small change like a few mm increase in tire width causes a 4% decrease in drivetrain efficiency. We can feel four percent extra pedal force, but we cannot visualize it.
 

BikeMike

Active Member
The front derailleur tirewidth is a standard, so manufacturers don't have to adjust the very sensitive chainstay length. Tire width is limited.

The Q factor width is also a standard, from Shimano.

The manufacturer chainring plays a role, too. You'll notice Praxis chainring and cranks, not Shimano. It's very detailed.

No, I am saying that designers make tradeoffs. They favor certain benefits and costs. For example, a small change like a few mm increase in tire width causes a 4% decrease in drivetrain efficiency. We can feel four percent extra pedal force, but we cannot visualize it.
This is a complicated subject. The only way to make sense of it is to start with bike geometry. The bike manufacturer has to add components from different suppliers. The components have technical specifications. These small differences can result in vastly different outcomes. It's very technical and complex.
 

BikeMike

Active Member
This is a complicated subject. The only way to make sense of it is to start with bike geometry. The bike manufacturer has to add components from different suppliers. The components have technical specifications. These small differences can result in vastly different outcomes. It's very technical and complex.
I am waiting to hear back from Specialized. I want to know what impacts motor and battery performance between the models. Only a few differences come to mind.
  • bike weight
  • drivetrain efficiency
  • wheelset. By wheelset i mean rim aerodynamics, tire width and presure.
 

BikeMike

Active Member
I try to understand the designer's thought process. I compare components on different models. I try to answer the question why this component, for this priced bike? Am i getting what i pay for?

The lack of a double chain ring model tells me a great deal about the designers' thought process. Do Gravel riders have higher priority than road cyclists? what are the other reasons? Technical or marketing?

I see the double chain as a tradeoff for motor power. You gain motor power, but lose the big chainring. That is very informative. The solution is highly constrained, so its easy to figure out.
 
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BikeMike

Active Member
The direct consequences impact the rear derailleur options. The double and single chainring rear derailleurs are different sizes. They use different number of teeth and chains. more or less components from third party manufacturers are available. The rear derailleurs need different tension to keep the chain from popping off. On and on... you feel the difference.
 

BikeMike

Active Member
In my experience:
  • 1x components wear faster than 2x.
  • The 1x chain and rear derailleur twist more than 2x.
  • The 1x feels weaker to me, due to power loss.
  • The 1x has less precision in gear spacing.
  • A 2x has a front derailleur to keep the chain from popping off.

Compromise is the name of the game. As long as you gain more than you give up, you are ahead.

I prefer a 2x drivetrain.

"The 1X drivetrain is as efficient as 96.0% and as inefficient as 92.4%. ... On average it's 96.2% efficient. CeramicSpeed calculated that the average friction for the 1X drivetrain was 12.24 watts. This was determined by adding together the drivetrain power losses in each of the 11 gears, then divided by 11."
 
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BikeMike

Active Member
I want to optimize speed in the 20 to 25mph range. How much the chain twists, derailleur cage bends and chain rubs against the cogs at that speed range is the efficiency loss. You can hear, feel and see it.

Optimizing the drivetrain is important to me. A 1x is not a showstopper, but it needs special attention. Probably requires chain cleaning and lubing after every ride.

The bike is heavier, so the lower gearing is important when riding unpowered. I expect to ride unpowered for ten miles on a long ride.

I am not sure how much friction is induced by the motor when decoupled. Supposedly, the friction is unnoticeable.
 
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BikeMike

Active Member
The bottom bracket width is one reason for the single chainring and boost hub. Article.

"The size of the bottom bracket motor is smaller than pretty much any other unit we’ve seen, but it is still bigger than a standard BB — the Q-factor on the Creo is wider than standard at over 80mm. To ensure a usable drivetrain the bike is single ringed with a Boost (148mm) rear axle."
IMG_0914.JPG
 
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BikeMike

Active Member
The tradeoff to get the motor means
  • unnatural gearing for me.
  • My stance will probably also be unnatural due to the wide Q factor.
  • I will likely need to adjust the gearing, if feasible and possible.
  • Clean and lube the chain after every ride to maximize drivetrain efficiency
  • Buy the model with the most appropriate rear derailleur
  • Use the bike for gravel and bikepacking.
  • Be as willing to ride unpowered as much or more than powered. Bike paths require unpowered, because class 3.

"Research from The University of Birmingham in the United Kingdom suggests narrower Q Factors are more efficient, likely due to improved application of force during the pedal stroke, as well the potential for reduced knee variability and risk of injury.[6][7]"

Wiki
 
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BikeMike

Active Member
The Case for a Fast Touring Bike
Could be a very cool eBike, depending upon range. Take the drudgery out of touring long distances.

  1. What distance can be achieved by optimizing the *Turbo Creo SL Expert* or Turbo Creo SL Comp Carbonfor:
    1. 15 to 20mph speed range
    2. Front and rear racks with light load (e.g., 20 pounds)
    3. 480 watt-hour distance (two batteries, 320 + 160)
  2. How to reconfigure the three power modes for optimal low power use between 15 to 20mph?
    1. For example, 15%, 30% and 45% ?
  3. How is endurance improved?
    1. What is maximum unpowered distance I can pedal?
  4. What is the powered-to-unpowered mile ratio for 100 miles per day?
  5. Is Smart Control feature of the Mission Control app more effective than configuring power assist mode?
  6. What is 100 mile elapsed time? 5 to 8 hours?
  7. Can I ride for two, consecutive 100 mile days over a weekend?
Substitute the ABC variables that are most important to you.

A - Unpowered Characteristics
  1. Weight
  2. Gearing naturalness/suitability
  3. Decoupled motor performance
  4. Endurance benefits
B - Powered Characteristics
  1. Battery Range optimized for 15 to 20mph
  2. Maximum speed: 20mph
  3. Recharge
    1. Time 3.5 hours for both batteries
    2. Recharge availability when camping?
C - Ride Characteristics
  1. Aerodynamics
  2. Bike geometry
  3. Tire
    1. Pressure - guessing about 60 PSI.
    2. 28mm width
  4. How much inefficiency due to racks with 20 pound load?
    1. Guess: 5 to 10%
  5. Most suitable rear derailleur model?
    1. Comp - Shimano RX812 GX, Shadow Plus, 11-speed
    2. Expert - Shimano Deore XT Di2, Shadow Plus, 11-speed
      1. Is Di2 shifting synchronized with motor cutoff?

S - stands for Symmetry, which means equally balanced, or a 1:1:1 ratio.

1593431921673.png
The harder part is naming the subsets:

  1. AB - High Performance
  2. SB - eBike-orientated
  3. BC - Elegant
  4. SC - Ride-orientated
  5. AC - Fast Touring bike
  6. SA - Road Cyclist-orientated
  7. U - Unknown

Here's a route that has practical value to me:
BikeDenverToFortCollins.png
 

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BikeMike

Active Member
Is my Topeak rack compatible? I know the Creo lacks seat stay bosses. The rack would connect to the seat post on the Creo. I am not sure about the dropout attachment.



IMG_1700.jpeg
 

StmbtDave

Active Member
The Creo does have threaded holes on the drop outs for rack mounting. Rather than making the attachment to the seat post itself, order the Specialized rear rack seat collar. This is a seat post clamp with threaded side holes for a rack attachment.
 

BikeMike

Active Member
I have narrowed the model down to the Turbo Creo SL Comp Carbon (the product names are an entire sentence). I can only justify the increased cost of the Di2 shifters when the shifters are synchronized with the motor to cut power. This lack of integration reflects a level of immaturity on product development. The integration disappointment actually extends further. I am surprised the Di2 and SL battery are not integrated. A small inconvenience that puts doubt into my mind. I will probably carry two separate chargers for the two batteries to reduce recharge time by one hour. A charger for the Di2 shifter is unnecessary weight and hassle.

The extender battery charges much slower than the main battery. I would love to plan my trips so that the extender became unnecessary. Just more weight and hassle.

The DT Swiss R470 rims have a 20mm inner width. The difference between SL 28mm and Evo 38mm tires is another compromise. 28mm have better performance. 38mm have better traction on gravel surfaces. The deciding factor is whether 28 or 38mm tires are better matched to 20mm rims. I will swap the 28mm tires for the larger 38mm Evo tires. 20mm rims are on the wide side for 28mm tires. 20mm rims are in the mid width for 38mm tires.

The important idea is gaining insight into the designer's thought process. Again, the design compromise favors gravel over road cyclists. I go with the design philosophy, rather than fight it.

The rear derailleur, Shimano RX812 GX, Shadow Plus, 11-speed, is gravel specific. All indications point towards a gravel design orientation. The SL model is clever marketing backed by sophisticated design.

Now that I understand who this bike was primarily designed for, I need to go back to the bike geometry to decide whether the geometry is a good compromise for touring. I love the Diverge geometry because the compromises strike such a great balance. The question in my mind is whether the Diverge geometry is suitable for touring.

Having a rack or not is a binary choice to me. I would not buy a bike with the intention or removing the rack to suit different purposes. I need to ensure the bike geometry precludes heel strikes, if a rack is to be used. Otherwise, i need to carry cargo in bikepacking bags. BIkepacking bags are probably better because they have about 5% to 10% less wind resistance. Wind resistance will affect battery life. This is another compromise decision. Racks have many advantages. I favor battery life in this case. Nothing is perfect.

I can use two of my bikepacking bags. I probably need to order a custom frame bag for the Creo. The wide battery downtube is actually an advantage for frame bags volume.
 
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Stefan Mikes

Well-Known Member
Region
Europe
City
Brwinów (PL)
I am pretty confident that I need to replace the 46T chainring, based on my existing bikes.

BikeMike,
Before you consider replacing the chain-ring, make sure you can really buy such a replacement. e-bikes are custom, and Specialized full company name is Specialized Bicycle Components. You might be bitterly disappointed when it would turn out you couldn't mod your Creo. (Some Forum members tried to make a second wheel set for their Creos and could not do it).

Just saying.

Can your LBS provide the Vado 5.0 (not SL) for a demo ride or by return policy? Turbo e-bikes allow any configuration of the pedal-assistance by Mission Control app. Of course, the Vado is not a road bike (it is a fast commuter), the battery is 604 Wh, the bike is heavy for you, and you cannot ride it in the aero position; it has the 48T chainring. Riding Vado 5.0 ("heavy") would be a good experiment how much power is drawn from the battery on a fast, long, forward-position ride. You could set up the Smart Control in the Mission Control for, e.g., 70-mile ride, your predicted elevation gain and, say, 10% battery left; Smart Control would be automatically adjusting the pedal-assistance on the ride.

You might be positively surprised. My brother is a fit person but he cannot match your power. He was making either 10 mile Vado 5.0 rides at 28-29 mph with average speed of 20 mph (city traffic rides), or he was capable to make 62.3 miles on "20/20" pedalling assistance in 4 hours on-road (because he had to ride with me, and I'm a weak person).

You might discover you didn't need an e-road-bike but rather a fast commuter. Or, you would collect enough information to make your decision regarding the Creo.

Vado 5.0 is optimized for speed.
 

BikeMike

Active Member
BikeMike,
Before you consider replacing the chain-ring, make sure you can really buy such a replacement. e-bikes are custom, and Specialized full company name is Specialized Bicycle Components. You might be bitterly disappointed when it would turn out you couldn't mod your Creo. (Some Forum members tried to make a second wheel set for their Creos and could not do it).

Just saying.

Can your LBS provide the Vado 5.0 (not SL) for a demo ride or by return policy? Turbo e-bikes allow any configuration of the pedal-assistance by Mission Control app. Of course, the Vado is not a road bike (it is a fast commuter), the battery is 604 Wh, the bike is heavy for you, and you cannot ride it in the aero position; it has the 48T chainring. Riding Vado 5.0 ("heavy") would be a good experiment how much power is drawn from the battery on a fast, long, forward-position ride. You could set up the Smart Control in the Mission Control for, e.g., 70-mile ride, your predicted elevation gain and, say, 10% battery left; Smart Control would be automatically adjusting the pedal-assistance on the ride.

You might be positively surprised. My brother is a fit person but he cannot match your power. He was making either 10 mile Vado 5.0 rides at 28-29 mph with average speed of 20 mph (city traffic rides), or he was capable to make 62.3 miles on "20/20" pedalling assistance in 4 hours on-road (because he had to ride with me, and I'm a weak person).

You might discover you didn't need an e-road-bike but rather a fast commuter. Or, you would collect enough information to make your decision regarding the Creo.

Vado 5.0 is optimized for speed.
Yes, I'm very wary about incompatible components.

My LBS actually has a Creo in the demo fleet. The demo program is shutdown until further notice.

I did ride their Vado 3.0? demo a few years ago. I liked the bike. It felt heavy and dull, but OK.