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single speed rear > 39/53 crank = chain tensioner ???(5 posts)

single speed rear > 39/53 crank = chain tensioner ???wes_london
Jul 18, 2001 4:54 AM
yet ANOTHER build project.

i have a nice road frame that i cant bear to sell and would like to know if there is a possibilty to make a single speed from it BUT with a twist.

i am planning on building a flip-flop rear wheel and as i have a few bastard hills between me and everywhere i plan to ride i am trying to figure out whether i can keep my 39/53 crankset. apart from using an old rear derailleur are there any chain tensioner's that will do the job required.

in effect i am trying to make a sort of minimal two speed with a front derailleur and a single brake caliper. should i try something a litlle closer in ring sizes like a 42/50 to limit the length of chain required.

am i absolutely mad or is there a way to do this. and still keep reasonable chain tesnion and alignment. this bike will serve mostly as a commuter.

any advice is appreciated.

ciao, wes
Maybe an extra chainring?Spoke Wrench
Jul 18, 2001 5:27 AM
I once saw a tandem that had a "floating chainring" wedged between the upper and lower runs of the front chain. I was told it was used insted of an eccentric to take up the chain slack.

Good luck
Maybe an extra chainring?Jofa
Jul 18, 2001 8:30 AM
I've seen this as well. It looks really odd, in an appealing sort of way: it rotates around a non-existent axle. However I think the query was for a tensioner which could take up variable slack, in order that the front mech could still be used. I know there is a custom built sprung tensioner expressly designed for single-speed conversions out there somewhere, only I can't remember where I saw it... it may have been on Sheldon's site (sheldonbrown.com) or Keith Bontrager's (er... bontrager.com? I think). Otherwise there's no reason why you can't use an old mech. I have an 80's Mavic SSC mech hanging around for just this purpose, when I finally get around to putting that single-speed together.
to answer the questions posednm
Jul 18, 2001 9:07 AM
yes, you can use the 39/53, you will just need use "odd" cogs in the back... yes, there are chain tensioners our there (Surly and others make them).
You are completely mad!jpa
Jul 18, 2001 6:30 PM
What you are looking for is called the Singleator ($39.95), made by Surly. Call Excel Sports at 800-627-6664. They carry lots of single speed parts and can help you get your project dialed in correctly. Many of their employees are also completely mad so you guys should hit it off!