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Technical & Reference Section => Tech and Restoration => Topic started by: BENDYCAT ELEVENTEEN on September 03, 2012, 02:19 PM

Title: chain ring to freewheel sizing ?
Post by: BENDYCAT ELEVENTEEN on September 03, 2012, 02:19 PM

A 39 tooth chain ring - what size freewheel ?

i know you can have a fast start feel or  more pace with a bigger size

just wondered what size do what ?

cheers B  ;)

Title: Re: chain ring to freewheel sizing ?
Post by: oldschoolace on September 03, 2012, 02:21 PM

15?  :-\

Title: Re: chain ring to freewheel sizing ?
Post by: Jon The Bassist on September 03, 2012, 02:37 PM

On a 20" BMX you want a chainring to freewheel ratio of about 2.75, eg 44/16, 39/14 etc.
Anything that makes the ratio bigger gives more top speed.
Anything that makes the ratio smaller gives more acceleration.

Title: Re: chain ring to freewheel sizing ?
Post by: BENDYCAT ELEVENTEEN on September 03, 2012, 03:02 PM

so does a 14t fit on a normal hub or is it the double sided hub it needs ? ???

Title: Re: chain ring to freewheel sizing ?
Post by: mattuknc on September 03, 2012, 03:11 PM

Quote from: BENDYCAT ELEVENTEEN on September 03, 2012, 03:02 PM

so does a 14t fit on a normal hub or is it the double sided hub it needs ? ???

Yep, you'll need a flip flop hub or whatever they're called for a 14t.  :daumenhoch:

Title: Re: chain ring to freewheel sizing ?
Post by: Spen69 on September 04, 2012, 11:13 AM

Yep, you need a flip-flop hub.

I run an Odyssey 13T freewheel on my Badlander as it's the smallest you can get for a 30mm metric side on a flip-flop which let's me run a 36T chainring on a 110mm BCD powerdisc. Any smaller will clip the chain and you will need a small 110mm BCD spider to avoid this which wasn't an option on a park bike.