Old MTB converted to a single speed cruiser.

[tlaverty79]

I have and old steel frame that I want to convert to a cruiser 26" Wheel BMX (type) using low rise BMX bars and stem and a single speed chainset.
What gear ratio should in be looking at for a relaxed ride? I live in Glasgow which is a wee bit hilly.
Cheers
Tony

PS. Something like the attached pic.

 

[xerxes]

Re:

Do you have another bicycle with 26" wheels and multiple gears?

If so, ride around on that, find which gear you find comfortable, count the teeth on the front chainring and rear sprocket for that gear.

You could then simply use that combination on your single speed, or you can work out the gear ratio or gear inches for that combination and find other combinations that will give you a similar ratio: http://www.bikecalc.com/gear_inches

Using 26" wheels with 2" tyres, you can see that a 46 tooth front chainring with an 18 tooth rear sprocket gives you a gear inch of 66.58, meaning that the bicycle moves 66.58 inches for every revolution of the crank. A combination of a 36 tooth chainring with a 14 tooth rear sprocket gives a very similar gear inch ratio of 66.84. So you could use either combination for a similar effective gear.

One last thing to consider, is that a in a combination of chainrings and sprockets with more teeth overall will last longer as the wear is spread over more teeth. I swapped the 32 tooth chainring on my crank set for 36 tooth chainring, it meant I use the fast wearing little 11 tooth sprocket on the rear much less.

 

[tlaverty79]

Sweet.
Cheers Xerxes

 

[hamster]

Close but no cigar: 26"x2 with 46/16 gives a gear inch of 66" approx - this is the equivalent diameter of the wheel, not the gear development or distance forward.

Multiply by Pi to get the development.

Anyway, a gear ratio of around 2:1 is a good starting point for mixed use (giving around a 52" gear), 70" is the usual road fixie sort of size.

 

[xerxes]

Re:

Ah, OK, I think I'm mixing that up with the metric Gear Metres system, which does measure the forward movement. However, using the tables it still works out, if you know the combination of front and rear teeth counts you like, you can find close equivalents that will give you a similar "feel" whilst riding.