What Happens to Your Bike Fit (when you change crank length?) with Road Cycling Academy
Source: Road Cycling Academy Youtube Channel: What Happens to Your Bike Fit (when you change crank length?)
Video What Happens to Your Bike Fit (when you change crank length?) with Road Cycling Academy
Video What Happens to Your Bike Fit (when you change crank length?) with Road Cycling Academy YouTube Channel.
What Happens to Your Bike Fit (when you change crank length?)
Road Cycling Academy
Understanding Crank Length: A Key Factor in Cycling Performance
At the Road Cycling Academy (RCA), the journey into optimizing cycling performance is a continuous one. Recently, RCA delved into an intriguing experiment involving crank length adjustments. The aim was to unravel the complexities of how different crank lengths can impact pedaling efficiency and overall cycling experience. Through this exploration, various insights emerged that could significantly aid cyclists of all levels in tailoring their setups.
The Experiment: Crank Length Testing 101
Crank Length Variations
In this comprehensive test, cyclists were equipped with various crank lengths: 155mm, 160mm, and 172.5mm. What made this experiment noteworthy was the extensive background of the main tester, who had been accustomed to using 165mm cranks for nearly a decade. This background provided a solid baseline for assessing the impact of changing crank lengths.
Evaluating Performance and Position
One of the significant findings was how changing crank lengths necessitates adjustments in the rider’s position. With the shorter crank lengths, notably the 155mm, the seat height had to be adjusted upwards by 13mm. This evidence highlights that a simple one-to-one adjustment is not always applicable; in fact, adjustments may extend beyond that standard ratio. As the study revealed, accommodating shorter cranks often requires additional increases in seat height to maintain a comfortable and efficient pedaling position.
Positional Changes Table
Here is a summary of the positional changes noted during the testing periods:
- **Original Crank (165mm):** Seat Height: 755mm | Setback: 34mm
- **155mm Crank Adjustments:** Seat Height: 768mm (up 13mm) | Setback: 31mm (back 3mm)
- **160mm Crank Adjustments:** Seat Height: 761mm (up 6mm) | Setback: 30mm (back 4mm)
- **172.5mm Crank Adjustments:** Seat Height: 743mm (down 12mm) | Setback: 36mm (forward 2mm)
Understanding Neuromuscular Coordination
Impact on Performance
Another significant takeaway from the study was the relationship between crank length and neuromuscular coordination. The shorter the crank, the more challenging it was for the tester to maintain a high intensity during certain performance measures. This distinction proves that individual physiology plays a crucial role in how cyclists respond to crank adjustments, and underscores the necessity of personalized approaches in cycling setups.
Cadence and Power Output
Power output is intricately tied to leg cadence. Shorter cranks often require cyclists to maintain a higher cadence to achieve an equivalent power output. This becomes particularly relevant in situations involving steep gradients or high demands for burst power—a crucial consideration for competitive cyclists. Test results indicated that with shorter cranks, producing short bursts of power became increasingly difficult, emphasizing the importance of selecting crank lengths that complement a rider’s unique power and cadence capabilities.
Pros and Cons of Different Crank Lengths
After the aggressive testing, distinct pros and cons emerged relating to each crank length. Here’s a summarized breakdown:
155mm Cranks
- **Pros:** Improved aerodynamics; better alignment for long, flat rides.
- **Cons:** Difficulty generating high burst power, especially on climbs.
160mm Cranks
- **Pros:** Intermediate balance providing decent performance across various conditions.
- **Cons:** Potentially requires careful adjustment to find optimal position.
172.5mm Cranks
- **Pros:** Increased leverage for standing climbs and potentially higher power generation.
- **Cons:** Compromised aerodynamics; noticeable difficulty maintaining extended power output at lower cadences.
Final Thoughts: Choosing Your Crank Length
The findings from RCA’s crank length experiment showcase the importance of individualized assessments in bicycle fitting. Factors such as leg length, riding style, and personal comfort levels heavily influence the ideal crank length for each rider. For instance, the tester found a return to the 165mm cranks provided the best balance for both comfort and performance. However, this will vary widely across different cyclists.
Advice for Cyclists
As riders experiment with crank lengths, RCA recommends using incremental adjustments and documenting the changes you experience. Assessments should be based not only on immediate output but also on comfort during extended rides and varied terrains. Analyzing power numbers will play a crucial role in determining optimal crank length for each individual.
Stay Tuned for More Insights!
The Road Cycling Academy will continue to publish valuable insights and findings; stay tuned for our upcoming video focused on the power numbers produced during the crank length testing. These additional results will further our understanding of how changes in crank length impact cycling performance.
The opinions expressed in this space are the sole responsibility of the YouTube Channel Road Cycling Academy and do not necessarily represent the views of Bicycles4ever Cycling Culture.