Could any one advice me on a single speed ratio for my Cotic roadrat?
Going to use the bike mainly to commute 30k one way with around 450 meters of climbs the biggest climb on the route is 11.7% on strava but only last’s 0.9k.
Any help would be appreciated as this single speed is all new to me.

Thanks

70 gear inches is a good all round gear. I run 48/18 which can get you up some pretty steep hills if you’re prepared to work hard. I top out around 20mph on the flat and it’s not too hard to start off from stationary.

RR is a lovely bike. I miss mine,

Single speeding. Pick a gear. It will be the wrong one.

Serious for a moment, it depends on how you ride. Are you a masher or a spinner? The problem with steep hills are you either pick a gear to get up it and spin it on the flat, or you pick something sensible for the flat and then graunch and gurn your way up the hills.

Do you have gears on it now? If so, pick a ratio, then ride without changing. It will take a few rides but you’ll have a better idea of the right ratio.

Sometimes though just pick one and get on with it.

I set my SS MTB up so I can just get up the hardest climbs. The trade-off is top speed on the flat. Take your geared bike out on the route and figure out the highest gear you can just grind up the steepest hill in. Then try that gear on the flat and figure out if it’s going to be acceptably non-spinny. If it is – set up the gearing the same on the singlespeed. If it’s too spinny you’ll need a higher gear but will end up walking up the hill until you find a power:weight improvement. If the circumference of the wheels differs you need to read up on gear-inches on sheldon brown. As you get used to it you’ll find you can increase the gearing.

Looking at the cotic site – that looks a thing of beauty!

Thanks for the reply’s.
No gears on it at the moment as it’s a new build. I’m doing the commute mainly now on my mtb 29er and just fancied something different.Will try to do it on single gear next week to try out the best ratio.

Thanks

Your legs will adjust quite easily to whatever gear you pick, so you should err on the bigger side. Do as jonwe suggests and ride the hill in the biggest gear you can so it feels ‘hard’, but not life and death, to get up it. Then take that as a starting point for the singlespeed.

It’s also much easier and cheaper to change rear cogs, so put something like a 48 on the front and you can then experiment with different ratios at the back.

70-72 GI

65 inches was the traditional gear back when chaps did everything on one speed, including riding around the world.

60 for the gentlewomen.

Picking a SS gear is a bit easier than fixed as you can use a slight lower gear and coast downhills rather than spin at 200rpm. Especially true for off road as I use a much lower gear and just forget trying to go fast downhill.

Starting off in the high 60’s (GI) is always good and then tailor from there. I favoured around 66 on road gets me 20mph at 100rpm but still low enough for climbing.

I ran 42:16 on a reasonably hilly commute. I did consider pushing a bigger gear, but when you’re riding into the wind it gets hard enough as it is.

I’m running 42×17 at the minute, which is more my winter gear and come back to a 42×16 spring/summer.

Picking a SS gear is a bit easier than fixed as you can use a slight lower gear and coast downhills rather than spin at 200rpm

See I’d not agree. Well i agreewith what you said but on the flat spinning is much easier on a fixed gear.

For your ride, 42×16 will be fine. Since you are freewheel, you can coast downhill. That gear is set for 16 mph at 90 rpm and is a good compromise. 42×15 is better for a fixed and flatterride. I ride 42×14, and this week it was hard into a headwind and very hard over Northwood Hills with 7 kilos of luggage.

I’m happy spinning and have some big hills on my commute so current run 36×16 on my commuter (not a road bike) but pedal at a cadence of 110.