The last months I rode my 29er a lot again, for faster XC/muni.

I have dual hole cranks, and mostly I ride with the 165 mm holes, it gives me the best control.

The last five rides I gave the 137 holes a try. After getting used to the shorter crank length it felt smooth, and easy xc in the mud wasn't a big problem. I am really confident with this length now.

I was getting very curious about the speed, so I put a cycle computer on the T-bar. To my surprise my top speed is 21 km/h (for mph divide by 1.6 ). The cruising speed is 16 km/h, 10 mph.

Today I wanted to find out how fast I can go with 165 cranklength. I gave it a short try in the neighbourhood and I found out that the speed difference is very small.

I got a top speed of 20 km/h, I only did a few tries. The cruising speed is 16 km/h, so no change. It is more work to spin the bigger circles however.

I was expecting more speed difference. The cranklength difference is 17%, and I get 5% more topspeed. Difference is cruising speed is even less.

What could be the reason:

1) going 21 km/h means that I spin 150 rpm. I know from my singlespeed MTB period that my topspeed was also at 150 rpm, with 175 mm cranks of course.

Could it be that my legs can't go faster, at any crank length?

2) 5 rides of 1,5 hours is not enough to benefit from a short crank length?

3) I am 6'3" and have long legs, maybe it is easy for me to spin big cranks fast. (I suppose 150rpm is fast???)

4) I rode MTB for far to long?

Can you think of any other reasons?

I leave the pedals in the 165 holes for now. It gives me more control offroad, at almost the same speed.

I am very curious about your comments.

I have dual hole cranks, and mostly I ride with the 165 mm holes, it gives me the best control.

The last five rides I gave the 137 holes a try. After getting used to the shorter crank length it felt smooth, and easy xc in the mud wasn't a big problem. I am really confident with this length now.

I was getting very curious about the speed, so I put a cycle computer on the T-bar. To my surprise my top speed is 21 km/h (for mph divide by 1.6 ). The cruising speed is 16 km/h, 10 mph.

Today I wanted to find out how fast I can go with 165 cranklength. I gave it a short try in the neighbourhood and I found out that the speed difference is very small.

I got a top speed of 20 km/h, I only did a few tries. The cruising speed is 16 km/h, so no change. It is more work to spin the bigger circles however.

I was expecting more speed difference. The cranklength difference is 17%, and I get 5% more topspeed. Difference is cruising speed is even less.

What could be the reason:

1) going 21 km/h means that I spin 150 rpm. I know from my singlespeed MTB period that my topspeed was also at 150 rpm, with 175 mm cranks of course.

Could it be that my legs can't go faster, at any crank length?

2) 5 rides of 1,5 hours is not enough to benefit from a short crank length?

3) I am 6'3" and have long legs, maybe it is easy for me to spin big cranks fast. (I suppose 150rpm is fast???)

4) I rode MTB for far to long?

Can you think of any other reasons?

I leave the pedals in the 165 holes for now. It gives me more control offroad, at almost the same speed.

I am very curious about your comments.

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