I have a bike with vertical dropouts, and i want to calculate the proper gear ratio/chain link ammount to get good tension. i have found a couple calculators (below). my question is, what is the ideal chain stretch? one of these sites assumes there is a half inch of chain stretch.

https://eehouse.org/fixin/formfmu.php...ey=Stay_length

https://www.machinehead-software.co.u...engthcalc.html

I wouldnt bother with vertical drop outs, unless you're going singlespeed; at which case, I'd run a chain tensioner like a DMR or One-One or Rennen instead of trying to find a magic ratio.

Chains don't stretch, they sort of "erode" on the inside as you ride. See what Sheldon had to say about this. https://www.sheldonbrown.com/chains.html [5th item down the list]

^This is also excellent advice

You people do realize they make a hub for this specific purpose? White industires eccentric fixed hub.

...yes, that, if the budget allows. I have no experience with WI's eccentric hubs, but I've used their freewheels and would definitely purchase their products again.

So does anyone have one and like it?

what kind of frame is it? the eccentric hub costs like $140. if your back wheel is going to be worth more than the rest of your bike, it's time to find a different frame.

this is for my gary fisher wahoo mtn bike which i converted to a single speed. i figured this would be better in the singlespeed forum then the mtn bike one. i have a hanging chain tensioner, but i am trying to sell it, and i think it would sell easier if it had the "clean" look. (as stupid as that is)

So you're looking for the "magic ratio" so you won't need a tensioner. I don't know how to calculate it, but I know how to make an educated guess.

Each additional chainring or cog tooth will take up about 1/4" of chain. Trial fit your wheel and figure out the closest place you can join your chain. Estimate how much too long or too short your chain is and acquire a chainring or freewheel that has the right number of teeth to fit.

I prefer the WI eccentric hub in a SS application w vertical drops over a fixed wheel application. If you have the money it's handsdown the best alternative to a vertical dropped frame if you must run SS.

You can also try an eccentric bottom bracket. I believe Bushnell makes one for standard BB's now, but I may be mistaken, and it's more expensive than the WI hub.

Or you could go all out and run a ghost ring:

Ghost chainrings... just don't do it.

Don't know about Bushnell, but Forward Components ( https://forwardcomponents.blogspot.co...et-patent.html
) and Triskstuff ( https://trickstuff.de/index.php?p=d116en1
) both have such a beast.

In the past, it's always been about trial and error for the magic gear, with the help of half-links, spare chainrings/cogs, and a tiny bit of filing.