Switching from single to double front chain wheel.

[BADGER.BRAD]

Hello All,

I'm thinking of switching my Revolution courier classic from single front chain ring to a double oval front setup (oval because I already have a set of oval Chain rings and crank arms) At present the front chain ring has 44 teeth which is fine for my hilly ride but makes the bike a little under geared for the flats or down hills, the double has a 42 and 52. My main questions are will the new crank be likely to fit due to crank taper and will the oval rings make it an unreliable shifter? A few people have told me that it will!

Many thanks for any help.

 

[mickle]

There are two versions of Shi**no's Biopace, the original shape with substantial ovality and the later (SG), less oval, pattern. The later type do shift better but not as well as modern rings equipped with shifting ramps and pins and profiled teef. The main issue, particularly with the original shape, is that because the front mech cage plate has to clear the ring at it's widest point it sits too far away from the ring at it's narrowest point to have much influence on the chain. Having said all that, it'll still shift. At the very worst it'll be a bit clattery going up.

You might need a new longer BB though.

 

[BADGER.BRAD]

Hello Mickle,

Thanks for the info, much appreciated. I did think about just adding an extra ring to the existing set up but one they seemed much too costly just for my knock around/commuter bike and two I'm not sure that the single chain ring was ever designed for the chain to be derailed.

Again thanks for your help.

 

[stan.shire]

The inner ring does not require any fancy pins or profiling so you could fit a larger chainring outside your 44. I don't know how the Courier is set up though -is it a double crank with only one chainring? You are right though that a new chainring and bolts will probably cost you just as much as buying a cheap double (which could easily be found second hand).