single speed rear tensioner?

howsmyriding27

hi I'm thinking of going single speed, but I was unsure if I need to get a rear chain tensioner as I already have a truvativ boxguide on the front. Do I need to get that extra rear tensioner, or will the front one suffice?

thanks

rob cole

does your frame have standard vertical dropouts?

or bmx style, horizontal dropouts?

or perhaps even sliding, vertical dropouts (where you have bolts and slots)?

with standard vertical MTB dropouts you need to run a chain tension device mounted on the derailleur hanger, to take up slack in the chain as you cannot tension the chain by moving the wheel forward / backward like is possible with horizontal dropouts

chainrings are never 100% round and the tension device allows for this slight movement which you will see as you pedal (tension device often bobs slightly)

sometimes you can find a size of chainring and rear sprocket plus your bikes chainstays length to get away without using a tension device, but this is rare, and often not ideal as the chain will stretch or the unround chainring will cause derailment

in my experience, the tension device mounted on the derailleur hanger is just as vulnerable as a rear derailleur so it makes sense to stick with gears on a frame using vertical dropouts, and leave the single speed setup to bikes with horizontal dropouts, or for frames with sliding vertical dropouts