Thinking about getting a SS roadbike and wondering what ratio I need to stop spinning out on the flat. On the geared cross bike I would cruise at circa 20mph on flat tarmac. Any suggestions?

Cheers
Rich

42:16 is the best place to start IMO. Smaller if you live somewhere hilly. Bigger if you live somewhere flat/have legs like Cav.

BTW, ss or fixie?

I have a 44/16 ratio which works out at a 72.5 gear inch. Good enough to get a good lick on but still small enough to get up the hills on my daily round. Maybe a 46/16 then?

42:16 fixed is a great winter training gear.

I took my SS down to North Cornwall last week – those 15% hills had me honking painfully out of the saddle, then shamefacedly getting off and walking, so if you live somewhere like that i’d suggest a smaller gear 😳

Singlespeed. Buying for the 25 mile ride from Dorking to London and back. There are about 3 hills though nothing major. Does anyone do this ride on a singlespeed can comment on that they ride?

I ride fixed mostly in flatish south west London on 49-17 (76 gi), cruising around 30kmh and spinning out at 50kph.

70-80 GI (spinning and honking respectively) is about standard for London.

48:17 for me. I’ve used higher (48:16) when I was fitter and/or living in reasonably flat places but that’s a good gear for cruising at 20ish and still gets me up most hills I encounter round here. Spins out about 32mph.

I started with 48 x18 and worked my way up to 48 x 16. I live in hilly (ish) north Wales and I manage ok. Watch the ol’ knees 😆
S’speed is awesome

63″ gear for me on the road. I know an (albeit very fit) person who keeps up on 17 mph av club rides on a 60″

As others have said, start on 42:16 or 48:18 (they are the same). This gears you for 80 rpm at about 16 mph. Cadence is 5x speed. Then as you get fitter you can drop to 48:17 or 48:16, which is my preferred gear for a flat commute and rolling club runs, this is the gear for 19 mph.

If you are still feeling brave, you can then go to 48:15, which I raced on (geared for 21mph). For this gear, I stripped the bike down, replaced the steel forks with carbon and ran lighter track wheels and tubs. It was too much even on the flat for commuting duties though.

And ride it fixed rather than SS, it is so much more efficient.

42:16 or 48:18 – same ratio..

48:18 is better as it is easier to increase gearing as you can fit a 17 or 16 and just shorten chain.. of if you have long track ends just move the wheel.

harder to do with 42-16 as hard to get smaller than 16t freewheels, bigger chaining will mean bigger chainring

I’m using 44-16 on my drop bar fixie at the minute, gets me up my local hills and can chop along on the flat at a comfortable 18-20mph rides are ~15 mile commutes mostly flat with about 270ft of short sharp climbs. Its OK for what I am using it for, I’d not want to use it for more than 30 miles at the minute, I need to get fitter but it is helping.

I ride out to the hills near Dorking from Kingston sometimes on my ss cx bike. 42:18.

Given that london is flat I would go with 48/17 to begin, I do Manchester on 48 /16 but it’s a bit of a grind