fixie chainsets?

zpin

hi all, i am halfway through converting an 1980's Holdsworth Avanti into a fixie, first one i've done.
i was wondering, how many teeth do i want on the chainring?
Could i just take off one of the ones on already? they are 52 and 42 tooth. i've tried to undo the bolts but they just spin, need a special tool? or is there a technique?

nicklouse

yes you need a a chain ring tools to hold the back of the bolt. a screwdriver can be made to work as can other things.

How many teeth that is up to you and what you can manage.

zpin

oh right, okay. How many teeth would you say is about right? i like to think i'm a strong cyclist, but there are a couple of killer hills nearby.

TiBoy

I run a 46 tooth on the front and 18 on the back and I have not had to stop on a hill yet plus gives a reasonable turn of speed on the flat. I would really recommend the VeloSolo website if you have any questions, it helped me a lot with my build.
http://www.velosolo.co.uk/faq.html

lae

^ yep. My singlespeed town bike is 46/18 and my countryside fixed gear is 48/18.

Around 70 gear inches is a good starting point, then you can vary it to suit your particular preferences and riding conditions.

The Sheldon Brown Gear Calculator is great for working out what size sprockets you need.
http://www.sheldonbrown.com/gears

gaspode

+1 for Sheldon's gear calculator - I'm currently running 42/16 which works for me both up and down hills - the downhill part is typically something you don't consider, but with a fixed-gear, you need to be careful that you can spin fast enough to match your downhill speed. With my old creaky knees, I tend to top out at about 22-23mph downhill - if I wanted to go faster, I'd need a bigger front (or smaller rear), but that would make the hills more of a challenge.....

oysterkite

48X17 Perfect!!!



+1 for Velosolo btw......

Velonutter

I rode a 49/20 and it was fine up to 30mph downhill, but got up the hills my way, I would have liked something around a 72", but may have struggled if i had gone further afield up some much bigger hills.

Monty Dog

Start with 42x16 and take it from there - get some shorter chainring bolts and refit it in the inner postion to get the right chainline if using a track/fixed gear hub. If planning to ride the South Downs, also keep both brakes fitted as you'll need them to control your speed on longer downhills.