Single speed gearing enquiry

[Grannygrinder]

I'm attempting to finish a bike for "The Wobble" at the weekend which will be single speed.I've fitted 38/16 gearing which to my amazement resulted in perfect chain tension so no need for a tensioner(which I am waiting for)Yippee! Only problem is that although it feels ok on the road I think it may too big a gear for offroad purposes.So I tried 18/38 thinking that as it was 2 extra teeth and therefore 1 complete link of chain,not so,now i'm half a link out and would require a tensioner which I don't currently have.So the question is,if 38/16 provides perfect chain length what other combinations will provide an even number of links?If you see what I mean?So that I won't have to run a tensioner. Complicated I know but if anyone can provide with the info you lot can!
Cheers in advance.
Mike

 

[Xesh]

It's not just gear ratios you have to consider, it's the length of the chainstays too. You'll probably find, as I did, that just because your chain was the perfect length on one bike doesn't mean to say it will be on another.

 

[velomaniac]

Get hold of a halflink or even a halflink chain which will make the whole tuning process much easier. If all else fails swallow your engineering pride and fit a tensioner.

Alternatively if the chain line could be moved inboard ie from the granny ring at the front to the inside edge of the freehub (provided you are using a freehub) then you can try 'Ghost Gear' as a interesting tensioning method, it looks really cool !
What you do is once you've decided on your ideal gear you get a spare chainring, use one of a similar tooth number to your front ring and place it in the chain line between chainring and sprocket behind the chainstay. You then move it backward until the chain becomes tight and the ghost ring cannot fall out because of the tension. The ghost ring then rotates with the chainring whilst not being attached to anything other than being in contact with the chain. Only the chainstay can spoil it if not enough clearance for the ghost ring is available hence keeping the chainline as inboard as possible.
Definitely a bit different and a talking point

 

[perry]

id run a tensioner ( well id change the frame to one with horizontal dropouts which is what i did but hey ho )

did the "magic gear " thing on my kona but the chain will soon wear

i dont like half links , they stretch easily because the outer plates are angled

 

[Grannygrinder]

Think i'll tough it out!!!

Why would the chain wear if the tension is correct? I think your chain may have been too tight.
I think i may try and tough it out with 38/16,if the going gets too tough I can always adjourn to the pub,thats if the rain doesn't drive me there first!

 

[perry]

chains wear out the bushings(pressed parts of sideplates in bushingless) in the rollers so the chain grows

i refuse to say they "stretch" as the plates dont get any longer , the bits just wear out so the distance between pins lengthens

itl be fine for the most part but will eventually get loose

you have to bare in mind that geared bikes share their wear over a number of sprockets , so generally the chain lasts longer as there are a multitude of teeth to distibute the load , with only the one it has to take all of the pedalling so doesnt last very long

id go with some decent steel chainrings and sprockets to keep it in the " magic gear " which does look much better than an unsightly tensioner

you might find this usefull too

http://software.bareknucklebrigade.com/ ... pplet.html

 

[Kona Paul]

Buy an Eno eccentric rear hub. Neat, clean, easy and no tensioner rquired.

 

[orange71]

I'm Wobbling on 34:16 and thinking that might be a bit high... but I know I won't be the only one pushing

 

[hamster]

Typically most people start around a 2:1 ratio (32/16, 34/17 etc) but it then depends very much on the terrain and your fitness / pain threshold.

Personally I run 32/17 as I am a bit fat at present, but it does result in comedy pedalling on the road.

 

[MikeD]

Why would the chain wear if the tension is correct?

By that logic, geared chains would never wear out