How do you determine crank arm length?
The crank length represents the distance between the centre of the bottom bracket and the centre of the pedal axis. The most common lengths are 170, 172.5 and 175 mm, but it is possible to find cranks between 165 and 180 mm in the market.
What crank length is for me?
Leg Length Measurement
| Crank Length(mm) | Inseam(cm) | Height, Male and Female* |
|---|---|---|
| 162.5 | 77 | Up to 166.3 cm Up to 5′ 5″ |
| 170 | 81 – 83.5 | 173 – 179 cm 5′ 8″ – 5′ 10½” |
| 172.5 | 83.5 – 86 | 179 – 185.5 cm 5′ 10½” – 6′ 1″ |
| 175 | 86 – 89.5 | 185.5 – 192 cm 6′ 1″ – 6′ 3½” |
Are 175 cranks too long?
The Basics. XC – Possible sizing needed depending on ride lengths, but 175’s are what is recommended for more leverage. Trail/Enduro – 170mm crank arm length is the most commonly used size and is recommended to keep a good leverage ratio and have a bit more ground clearance due to having more travel.
What difference does crank arm length make?
The relative jumps between gears stay the same, but the overall range will feel slightly easier to pedal, or smaller, with shorter cranks and harder with longer ones. If you’re only changing slightly—say, from 172.5mm to 170mm—it may not be an issue.
Should I use a shorter crank?
Moving to a shorter crank can improve: Comfort: A shorter crank length reduces range of motion at the knee (extension and flexion), hips, and low back. Aerodynamics: Going to a shorter crank will allow you to ride at a lower back angle which minimizes frontal surface area improving aerodynamics.
What is 170mm crank?
Why are we using the same range of crank lengths? The answer to that is that we probably aren’t. 30 years ago, 170mm was ‘normal’, 172.5mm was longish and 175mm was considered to be quite a long crank and relatively uncommon. Whereas now 170 is ‘short’ 172.5mm is ‘normal’ and 175 mm cranks are very common.
How long should my MTB cranks be?
The common range of mountain bike cranks across the industry is 165mm to 180mm (in 5mm increments) giving very tall or very short riders room to play around with their setup if needed.
What is the difference between 170mm and 175mm crankshaft?
Whereas now 170 is ‘short’ 172.5mm is ‘normal’ and 175 mm cranks are very common. Still though, the difference between 170 mm and 175mm is less than 3% and leg lengths of bike riders vary by far more than that.
How long should a bike crank arm be?
Now lets look at the same two riders on bikes. Both are riding crank arms that are 20% of inseam length yielding a 200 mm crank length for the very tall rider and a 160 mm crank length for the shorter rider.
How to calculate the perfect crank length?
If you really want to calculate your perfect crank length use this formulae Crank length (mm) = -0.0123x (squared) + 4.8121x – 293.8 where x = (inseam + GT height) in cm. Otherwise use the table below.
Should you change crank lengths when replacing cranks?
When done correctly, changing crank lengths can impact comfort, aerodynamics, clearance, and performance. Most cranksets are available in 160 mm, 165 mm, 170 mm, and 175 mm options. Though, 167.5mm, 172.5 mm, 177.5mm, and 180mm lengths are also available for certain cranksets.