# Questions tagged [math]

Calculation - questions asking for how to get a number as an answer.

7 questions
2answers
1k views

### How do I calculate the spring weight rating for my bike?

I have a home built bike design and the rear shock absorber that came with the part bottoms out so I want to get one that is more appropriate. But I have no idea how to calculate which one to buy as ...
2answers
8k views

### Calculate frame stack and reach

Is is possible to calculate stack and reach for framesize 63?
1answer
8k views

### Formula to calculate Single Speed Chain Length from Chainring Size, Cog Size, and Chainstay Length

I've seen formulas to calculate chain length for multi-speed bikes, but I need something for single speed. Example: 42T Chainring 17T Cog 406mm (16") Chainstay Length The answer in this case should ...
2answers
10k views

### How can i calculate the power in watts on an indoor trainer

I am trying to calculate the power needed to hold a steady speed on an indoor trainer, so as I can train using power in watts. I set the bike up and put the crank at 90 degrees, then put a weight of 2....
4answers
25k views

### How do I calculate the power required to climb a hill at a given cadence?

Suppose I ride at a cadence of 50RPM for 10 minutes with a 39x23 gear ratio on a hill with 10% grade. Is there a simple formula to calculate the power output required?
6answers
134k views

### How to calculate the capacity of a rear derailleur

It's easy to calculate what capacity of a rear derailleur will be needed based on the size of the big and small chainring and the big and small cog. What about the converse question, how to calculate ...
3answers
6k views

### How do I calculate spoke length?

I have lots of bikes and lots of interesting wheel sizes, I would like to know how to calculate the right spoke lengths for a wheel. I appreciate that there are probably rather a lot of variables but ...