29er Gear ratio question

stubs

I have ordered my first 29er frame which will be run single speed. I'm running a 38-16 (2.375 to 1) gear ratio on my current 26er single speed, I really like the ratio and want to run the same ratio on the new 29er.

Because of the larger wheels do I fit the same 38-16 gearing or do I need to change to get the same effective gear ratio.

To get a similar feeling ratio what combination of ring and sprocket do I need. Dont want to have to buy a range of screw on sprockets and experiment because budget is a bit tight on this build.

Feel like it should be an obvious answer but I cant work it out :? does anyone have a link to a spreadsheet where I can punch in numbers and get an idea.

nicklouse

looked in the FAQs?

there is a topic that will give you the means to work out what you need.

stubs

Yes had a look at the singlespeed topic but cant work out how to convert my 26er ratio to a similar feeling 29er ratio. Need an algorithm or a spreadsheet to work out what I need to buy. Decent freewheels are £20 plus a pop, cheapest option might be to buy a couple of cheapo fixed cogs and try them out see what size freewheel I need to buy.

stubs

Think I have worked it out. Used the numbers in fozzybears singlespeed info page. He used a magic number of 55 divided by the nominal wheel size to give a good starting ratio.

Worked out that my favourite 38-16 ratio gives 2.375 to 1, on a 26er wheel thats a magic number of 61.75.

61.75 divided by 29 gives me 2.13 therefore to get same effective ratio I need a 34-16 set up. That will give me something to start with.