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power2max models for BB30, PF30, BBRight and BB386EVO frames
We often get asked which model we recommend for a particular frame. To help you choose the right power meter we have put together an overview of the Type S models with cranks. Before we go into a side-by-side comparison let us share a bit of tech background on frame formats:
Evolution of bottom bracket standards
Until a few years ago, frames with a threaded bottom bracket area were most common. They came in two flavors: “english threaded” (or BSA) frames, which are 68mm wide, and “italian theaded” (or ITA) frames that are 70mm wide at the bottom bracket. Bottom bracket bearings were usually located inside the frame and used systems like square taper, Octalink or ISIS. Manufacturers then gradually switched to external bearing cups and 24mm steel axles. Shimano’s standard is called Hollowtech II, FSA’s is called Megaexo, SRAM owns GXP, and Campagnolo’s standard is called Ultratorque. If you have such a frame you can
With the introduction of the BB30 standard by Cannondale we got another axle diameter and a new family of frames. BB30 frames 68mm wide like BSA threaded frames, but the bearings are directly pressed into the frame and the axle has a diameter of 30mm. Following BB30 a host of other standards were developed and introduced: PF30, BBRight, BBRight Direct Fit, and BB386EVO. Here is how they compare (for road bikes):
| BB30 | PF30 | BBRight | BBRight Direct Fit | BB386EVO | |
| Frame width at the bottom bracket | 68mm | 68mm | 79mm | 79mm | 86mm |
| Bore diameter | 42mm | 46mm | 46mm | 42mm | 46mm |
| How are bearings installed? | Directly in the frame | With cups | With cups | Directly in the frame | With cups |
| Example | e.g., Felt IA1 | e.g., Cannondale Super Six EVO | e.g., Cervelo P5 | e.g., Cervelo R5 California | e.g., Merida Reacto |
Type S models for BB30, PF30, BBRight and BB386EVO
We have four Type S models with cranks that are made for the BB30 family of frames. Each one has its own advantages – take your pick and enjoy!
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| Model | FSA Gossamer BB386EVOTHE VALUE OPTION | FSA K-Force Light BB386EVOTHE LIGHT OPTION | Rotor 3D30THE VALUE ALTERNATIVE | Rotor 3D+POPULAR AND PROVEN |
| Crank material | Aluminum (forged) | Carbon | Aluminum (forged, hollow drilled) | Aluminum (CNC machined, hollow drilled) |
| Weight* | 786g* | 576g* | 678g* | 622g* |
| Crank lengths | 165, 170, 172.5, 175mm | 165, 170, 172.5, 175, 180mm | 170, 172.5, 175mm | 150, 155, 160, 165, 170, 172.5, 175, 180mm |
| Compatible frame formats | BB30, BB386EVO, BB86, BBRight, BBRight direct fit, BSA68, ITA70, PF30 | BB30, BB386EVO, BB86, BBRight, BBRight direct fit, BSA68, ITA70, PF30 | BB30, BB386EVO**, BB86**, BBRight, BBRight direct fit, BSA68, ITA70, PF30 | BB30, BB386EVO**, BB86**, BBRight, BBRight direct fit, BSA68, ITA70, PF30 |
| Price (with cranks) | $1099 AUD | $1499 AUD | $1399 AUD | $1499 AUD |
| Our thoughts | A great no-nonsense crank with amazing compatibility. Our value champion for modern frames. | Amazingly light and stiff. A challenger for the very popular 3D+. | The value alternative to the 3D+. | Extremely popular – great looks and big choice of available crank lengths |
* 110 compact version, 175mm cranks
**check compatiblity
Gear up for success: compact or standard cranks?
Following up from our post on crank length, today we will cover bolt circle diameter (or BCD) of your power meter, or cranks in general. The question of compact or standard cranks comes up quite often. Like on the topic of crank length there is no definitive rule on which BCD – compact or standard – to choose. But let’s start out with the basics of what BCD is and what the differences are:
Compact and standard crank BCD explained
The BCD, or bolt circle diameter of your power meter (or normal crank) defines how far the chain ring bolts are located from the center of the cranks. The power2max Type S Rotor 3D+ on the right is a compact model, which means the the diameter of the circle the chain ring bolts describe is 110mm, or 11cm in diameter. The other frequently used format is what’s called a “standard” crank with a BCD of 130mm, or 13cm.
Why is this important? Because it determines the gearing you can use on your bike. The BCD determines the smallest possible chain ring you can use at the front and, to some extent, also the biggest chain ring that’s available to you.
Other BCDs
Beyond compact and classic, the most frequent BCDs, there are also other ones in the market: Campagnolo uses 110/113 compact (a slight variation on “normal” compact, so chain rings aren’t compatible) and 135 instead of 130mm. Track cranks come in 144mm BCD, and manufacturers like Shimano and FSA now also introduce their own BCD formats, both in 110mm and with 4 bolts, but neither compatible with the other.
Typical chain ring combinations on compact and standard cranks
With compact cranks you can use a 34 tooth chain ring as the smallest option. With standard cranks 38 is the smallest possible chain ring size.
For the large chain ring, the limitations go in the other direction: big chain rings for compact (110 BCD) drive trains tend to go up to 52 teeth. For standard drive trains you can buy much bigger chain rings, up 56 and often even bigger. The reason that compact chain rings are often not available in bigger sizes than 52 is due to chain ring stiffness: the bigger the distance between the point where the chain rings are installed and the chain, the more chain rings will bend (other things being equal). This can influence the quality of shifting. However, with improved quality of chain rings, such as the Praxis Works chain rings we offer in combination with our power meters, stiffness is becoming less of a concern these days.
Typical chain ring combinations for compact cranks:
- 50/34 or 50/36 (compact)
- 52/36 (mid-compact or semi-compact)
- 52/38 or 53/38 (rarely used)
Typical chain ring combinations for standard cranks:
- 50/38 or 52/38
- 53/39 (most frequently chosen)
- 54/42, 55/42, 56/44 (typically used for time trials)
How to figure out if compact or standard cranks are right for you
The choice of compact versus standard comes down to the speeds at which you ride. If you live in a flat area like parts of Florida or have the legs of a Nairo Quintana or an Alejandro Valverde, then you will likely choose standard cranks. If you ride a lot in the mountains or like to take it at little easier a compact crank will suit you better.
To drill down into the details, use a tool like gear-calculator.com. It’s great at helping you figure out at which speed you will bottom out or spin out with your combination of cranks and cassette. An example:
A typical mountain gearing would be a 50/34 compact up front with an or 12/28 cassette at the back. If you want to maintain at least 80RPM cadence whilst climbing and consider 110RPM to be the upper limit, you see that with this gearing combination you get a range from 7.6mph (12.2kph for the metric minded) in the 34-28 gear at 80RPM to 35.9mph (57.7kph) at 110RPM in the 50-12.
A typical strong rider race gearing might be a 53/39 up front with a 11/25 at the back. Using the same cadence limits we get a lower “speed limit” of 9.8mph (15.7kph) at 80RPM and an upper limit of 41.5mph (66.7kph) at 110RPM. By moving from a mountain gearing to race gearing we lost 2.2mph at the lower end and gained 5.6mph at the upper end.
Mid-compact: the swiss army knife of gearing
Unless you are firmly on either the mountain or race gearing end of spectrum, a popular option is the swiss army knife of crank gearing: mid-compact. Mid-compact has a 36 small ring (so 3 teeth smaller than Classic, but only 2 bigger than compact) and a 52 big ring (1 smaller than classic, 2 bigger than compact).
Mid-compact has become a very popular choice of late, because it hardly sacrifices top end compared to a classic crank, yet almost has the climbing characteristics of a compact crank – a nice compromise!
Conclusion: it’s personal
The choice of compact versus classic is very personal and depends on the terrain you ride in and the level you ride at. For many uses compact cranks are a great choice, as they allow you to climb well in the mountains and can easily be changed to mid-compact.
Have fun, keep the rubber side down and the watts up!
Which crank length is right for me?
Which crank length is right for me? In many conversations with our customers we get asked for tips on which crank length is “the best” or “the right” one. As often in life the answer in life is a resounding: it depends! The choice of crank length is very much dependent on the person riding the bike and the type of riding you are going to do. So instead of trying to give a recommendation we will share some thoughts and information to help you choose.
What are the most common crank lengths?
Most road bikes are sold with cranks that are between 170mm and 175mm long. Smaller frames generally come with shorter cranks and bigger frames with longer cranks. On the track 165mm cranks are very common. Cross country and enduro mountain bikes are often sold with crank lengths in the 170mm to 175mm range. On downhill bikes we tend to see shorter cranks, often around 165mm. In time trialling and triathlon a recent trend has been to move towards shorter crank lengths, with more and more riders choosing cranks around 165mm to 170mm long.
What is my crank length?
Your current bike’s crank length is a good starting point. If you are comfortable and powerful on your bike and don’t have injury problems, there should be no reason to change lengths. “Never change a running system.”
On almost all cranks you will find the length marked on the inside of the crank arm near the pedal threads. The cranks in the picture on the right are 175mm long, as indicated by the “75″ marking.
What is the role of crank length?
The length of the crank arm is the lever arm when you pedal: the longer the crank, the greater the lever you have to produce torque, which helps you produce power. So we may be led to choose a very long crank to maximize the torque we produce when pedaling. Unfortunately it’s not as simple as that. Biomechanics come into play: the longer your cranks are, the lower the pedal will be in the 6 o-clock position, and the higher it will be in the 12 o-clock position.
A longer crank means you have to lower your saddle to keep the same leg extension. At the same time your knee will be higher when the pedal is in the 6 o-clock position. This requires a greater range of motion. If your crank is too long it may feel as if it’s difficult to get “over the top” of the pedal stroke. At worst it may lead you to compensate for a lack in range of motion and to incur injury. Alan Couzens has written an excellent article explaining this in detail. His conclusions are:
- A crank that’s too long may lead to compensation and, at worst, injury
- A crank that’s too short may lead to a loss of cycling economy as the athlete doesn’t use the full range of motion of her muscles
What lengths can I choose from?
We carry a large selection of cranks in our online shop. All models are available from 170mm to 175mm. Many are also available in 165mm. Our crank length super star is the Type S Rotor 3D+, which is available from 150mm to 180mm. The filter function on the right will help you choose the right model.
A nice characteristic of power2max power meters is that you can change crank length later on, which is not possible on power meters that are built into the crank arm. So if you damage your cranks in a crash or want to change their length for another reason you can simply swap them out and don’t need to purchase a new power meter.
Conclusion
In cycling, there is no such thing as “the right crank length.” Needs differ, based on morphology, biomechanics, and intended use. Before making dramatic changes to your crank length we recommend consulting with a competent bike fitter to avoid running the risk of injury.
Happy pedaling, keep watts up!
© power2max Australia, 2019