what sized chain ring and sprocket?

[jonny jeez]

I ride 48 x 14 round N London way not to many hills some can be a bit hard, but i still spin out going downhill, I think it's a case of trial and error, You can pick up cheap fixie cogs so not really a problem, And as long as you have horizontal drop outs you will not have to many problems with chain length, A good start point would be 48 x16 then go from there.

Good point

 

[jonny jeez]

http://www.sheldonbrown.com/gears/

If you use this but swap to MPH at RPM it should give you an idea of what to use.

Now that is what i was looking for, just to get a good start...thanks

 

[totallyfixed]

Okay so this might suit me as I am pretty strong and manage hills in a pretty high gear...small hills that is.

I've no idea I afraid



So do I need a a 40 20 to cruise at 20mph without spinning out?

Without wishing to complicate things, everyone has different maximum cadences.

 

[jonny jeez]

Without wishing to complicate things, everyone has different maximum cadences.

This is very true and I guess my comfy cadence is around 70 with a max of 90ish...before I feel like I am bobbing out the saddle (never actually measured my max cadence but I know what I am happy cruising at so have just added a bit here) I know we are supposed to ride at around 85-90 but I tend not to and select a higher gear...generally

I suppose I am looking for a ratio that allows me to reach 21mph with a cadence of 90rpn...on normal sized rims

 

[totallyfixed]

This is where riding fixed is a little different, your maximum cadence rises with experience, having short legs and short cranks helps a bit too, which I don't.

 

[Deleted member 1258]

This is where riding fixed is a little different, your maximum cadence rises with experience, having short legs and short cranks helps a bit too, which I don't.

Its strange how it can work, I'm vertically challenged and always descend better on short cranks. I'm running fixed, a Genesis Flyer, on a 46x18 and 170 cranks and run at 19-20 mph on the flat at about 100rpm cadence and start to get uncomfortable descending above 30mph.

 

[Texan]

i am also vertically stunted but need to post this as i need 5 posts to buy some goodies,hope you don't mind

Mod note: I hope you realise that's cheating! Just as well I've got a sense of humour....

 

[raleighnut]

i am also vertically stunted but need to post this as i need 5 posts to buy some goodies,hope you don't mind

Mod note: I hope you realise that's cheating! Just as well I've got a sense of humour....

Nip onto SC&P and post nobber a few times in different threads, should be easy.

 

[3narf]

This is very true and I guess my comfy cadence is around 70 with a max of 90ish...before I feel like I am bobbing out the saddle (never actually measured my max cadence but I know what I am happy cruising at so have just added a bit here) I know we are supposed to ride at around 85-90 but I tend not to and select a higher gear...generally

I suppose I am looking for a ratio that allows me to reach 21mph with a cadence of 90rpn...on normal sized rims

If you are bobbing up and down, your saddle might be a bit low...

 

[ayceejay]

Another question - are we talking about a single speed freewheel or a fixed wheel. If single the downhill won't be a problem so select a ratio for the flat and uphill. the problem is that freewheels are not so readily available as fixed cogs.

 

[ozboz]

When I get my old 28' frame up and running it is my intention to use this as a single speed , I was wondering the same for me , on my road bike I can comfortably ride on the big ring and mid on the rear , in a reply earlier it was said if you have no option to change then somehow you will manage , I will go with that at first , it will be a heavy bike by today's standards so I will have to compensate for that in some way

 

[zigzag]

i would suggest using big ring up front and then select the rear cog/freewheel accordingly. this way you will have more options if you want to have a higher gear, also big chainring feels a bit smoother and the chains last longer (but the whole setup adds a bit of weight, if that's important). when i ride single speed i usually have 52x16 gear as it gives me comfortable cruising speed of 22mph at 85rpm, hills are fine as long as they are not super steep. i used to gear down to 52x20 to work on spinning technique, but these days just use my geared bike with cadence sensor for that, keeping the cadence at around 110rpm.
i would recommend 52x18; you'd be going at 19mph at 85rpm.

 

[Ian H]

It's down to individual experience, but higher cadence is generally considered better. I'm happy at 90-110" and can manage in excess of 150 on downhills (it used to be well over 200, but I'm older than I used to be). I'm also in Devon, where there are HILLS, so factor that into my advice.

 

[nuovo_record]

The flat lands of Cambridge aren't a problem for a 52 front, but I'm now using a 48x19 which is quite nice.

 

[fossyant]

46 x 16 should be nice cruising at 20-24 mph - the gear I (used) to ride.