I just bought a used paddy wagon for my young teen son – just for transportation around Bristol. Mostly flat – occasionlly hills.
42 X 16t is way to hard for him (and for me). Will 18t feel much easier? Or should I be looking at a smaller front ring instead/as well?

40x18t?
38x18t?

Cog changes are bigger than chainring changes (if that makes sense).

Easiest thing to do is take a geared bike and find a gear combo that works. Then look at a gear ratio chart, see what length that gives you, then look at how you can get close to that with the SS setup by changing cog or chainring (or both).

Fill yer boots!

https://www.bikecalc.com/gear_inches

(Smaller gear inches = easier)

2 teeth on the cog will make noticeable difference, whether it’s enough of a difference will depend on how hard he’s finding it at present.

Try an 18t cog first, see how he gets on; if that’s still not enough, you could get a smaller chainring as well.

My son was riding his SS around Bristol, the hills are certainly in the short, sharp, steep, category. He was on 32/16 on an On One Inbred. He said he walked a few on the hills, and he’s normally a monster.

The old SS adage applies, pick a gear, it’ll be the wrong one.

I’ve got a couple of Sturmey Archer free wheels and chains that I bought to settle on my gear ratio on my town bike. Not sure what tooth count they are but they’ll be cheap if your interested.

Which part of Bristol is “Mostly flat – occasionlly hills”? I rode a single speed when I lived in Cardiff. I brought it with me to Bristol a lasted about a month before fitting gears.

@bigblackshed. PMed

Is I will be interested in what you’ve got. This is all very experimental stuff.

Mostly flat – Bedminster and surrounding. If he’s gonna head up to the downs then he can get off and push.

The paddy wagon was cheap. He’s had 2 bikes nicked in the last year. Decent locks too.

Is it actual singlespeed cog at back, or is a singlespeed freewheel on wheel? If so worth getting some cheap cogs (but always make sure the cog have a wide base to them so not the cheap thin ones that cut into freehub body) in the common ratios 16/17/18/19 and experiment with them, then as he gets stronger he can move down a size. Worked well for me.

Or, the other option if it is cogs at back, is to run it Dinglespeed, so you have two ratios, one for on flats and one for climbing and you just flick chain over?

This is handy for messing about with stuff virtually before you splash cash on stuff that only might work-

http://www.machinehead-software.co.uk/bike/chain_length/chainlengthcalc.html

Fow what it’s worth I like close to 52 gear inches gearing on an MTB as a good all round trail gear but for more roady stuff (on an MTB) I like a slightly higher gear around 55 gear inches. It’s still low enough to be spinning out going down the hills round here but not so high going back up that I wished I had a lower gear 😆

I ride 36:15 on my ancient 27″ fixed wheel which gives me around a 66″ gear. It’s just right for me, I’ve had it like that for about 15 years. It’s not too hilly where I live but I sometimes do a 20 miler on it.

42/18 will be ~66 gear inches with 32mm tyres, IIRC my old Tricross Singlecross on 25mm tyres sold to TimP on here had 42/17 and got me up a ~0.5 mile ~6% climb home from work ten years ago, when commutes were my only cycling and my lower back injury caused me far more grief.

bmx’s are relatively well geared for young teenagers to nip about town on, so I’d be looking at the gear inches and going from there. Instinctively, I’d suggest you need to be way smaller than a 38 on the front

Ah, Bedminster is sarf of the river. Boy1 was north side, the bit with all of the hills.

PM’d you back @Earl

bmx’s are relatively well geared for young teenagers to nip about town on, so I’d be looking at the gear inches and going from there. Instinctively, I’d suggest you need to be way smaller than a 38 on the front

BMX are geared very differently to a SS road bike, BMX is about having a small front chainring so it is tucked away to avoid damage, and then with a small rear cog. ON a road bike singlespeed, you want chain wrap round as larger chain ring and rear cog as possible really, so the opposite.

42×16 fixed was my glasgow gear, kinda surprising its too hard in bristol its pretty spinny on the flat which is a real pain on a freewheel.

is it a flipflop hub?

BMX are geared very differently to a SS road bike, BMX is about having a small front chainring so it is tucked away to avoid damage, and then with a small rear cog. ON a road bike singlespeed, you want chain wrap round as larger chain ring and rear cog as possible really, so the opposite

I think you’re maybe confusing gearing with cog size- gearing can be whatever you want as long as you can get the bits to make it work. (Freestyle) BMX gearing is ~56 gear inches (25:9) so on a 700c roady sort of thing with skinny tyres that’d be, what, 42:20 or 40:21 ish? Race BMXs are still using larger chainrings.