Nervous about committing to Single Speed

I agree, assuming there's hills etc. But there's a lot of fast fixed TTers out there who've presumably decided against gears for a reason. And in my personal experience the 'flywheel' effect of riding fixed helps to maintain speed once you're there.

The only real reason to ride fixed wheel is for enjoyment. There are marginal efficiency gains and perhaps psychological ones if you're the type who changes down as soon as it hurts, but mechanically gears are way faster in all circumstances. Except maybe a totally flat road on a totally still day with a perfectly chosen gear and perfectly judged pace.

No worries we were all learners once :)

the larger numbers mostly 42/46/48 etc etc refer to the front chainring size.
the smaller numbers are rear sprocket/freewheel sizes 14/15/16/17/18
Track bikes and fixed wheel bikes tend to go on GearInch ratios, this also applies to Single speeds, it's the langauge used for bragging rights or working out how hard your gear is going to be to spin up.
http://www.bikecalc.com is fun, feed it your details, tyre size (as this affects gear inch) and ring sizes and it will work out how fast you go at certain RPM of your legs.
I put in the Mangos 46x16x25mm tyre to work out it's GI of 76.2 when you look at a broad chart of many ring sizes you see overlap in gear ratios.
So Dancingjames 48x19 = 15mph with legs spinning at 75rpm and 66.9GI
My lower 42x18 = 15mph with legs spinning at 82rpm and 61.6GI
The Mangos 46x16 = 15mph with legs spinning at 66rpm and 76.2GI
That dosen't look much of a RPM difference, but on fixed your legs always spin no coasting, so while i might be quicker off the mark than James he can catch up and match my speed with less effort in cruising speed, James can drop the hammer wind his RPM up and i might spin my feet off the pedals trying to keep up, going down a hill on a spinny gear is not fun either.
So the lower the gear inch number the more spinny but easier to push it will be.

So the fairly high Mango rating of 76.2 tells us that a newbie may struggle to pull away from lights and junctions and you might experince knee pain and be a bit wobbly as you try to ride off. Sticking another freewheel on is cheap and going to 18t brings you down to 67.7GI so still a good cruising speed but easier to spin up, going to a 20t freewheel will drop it again to 60.9 so it will be super easy to start on, but high speed cruising will be spinny.
I did run a 22t for offroading, that was rideable on the road but slow cruising speed, 42x22 = 50.5GI and at 15mph a spinny 100RPM.

It's about tailoring how fast you want to cruise in comfort, how far you want to ride and how demanding is your ride, and how fit you are. There is no right ratio to reccomend, the right one is whatever your happy with and SS and Fixed are cheap to play around with to find the magic one for you.

...the 'flywheel' effect of riding fixed...

... is a canard.

Huh, who knew? So why do fixed TTers bother? What's the benefit?

The fun / heritage.

To get your excuses in early: "Yeah, should have geared-up/down and I'd have smashed that." ;)

Haha, now I don't know how to say this without sounding like a #boastpost bellend but quite a lot of my best times on strava segments are on my fixed gear. Especially uphill and flat ones. Why would this be? I probably use my fixed gear about a third of the time for commuting.

Fixed means you have to attack the hill and keep on going as if you stall or slow down on a hill you are fucked. But it takes its toll over a long ride. So for a century you are more likely to struggle later in the day if you do it fixed.

Buy a second hand No Logo for £50. If you love it, get a decent one now you have some experience. If ya hate it, sell it this summer.

8 years ago this'd be forum gold. All gone soft.

Hey CJ. I bought a second hand Specialized Langster for 250 quid 5 years ago. The aluminium one, not the steel one they're shit. came with 44 x 16 gears, which was fine, I later went up to 46 x 16 which I still run, and ride up to the top of Crystal palace every evening. It took me about two months to get completely comfortable riding fixed and I love it.

@853Superfly Thanks so much for your help. After all this great advice I've decided I'm going to ditch the Mango and try and build my own for the same budget. Hopefully it'll be a lot better! I'll probably make a thread in the projects section and see what people recommend for individual parts...

It'll definitely be a lot better! Welcome to the forum and sorry for diverting your thread a bit, looking forward to the project thread!

If you're building your own bike then you may well end up with a 42-tooth chainring from an old chainset. 42/17 is fine for spinning around town I find. I even sometimes go 42/18 if my knees aren't feeling too strong.

A quick quote from Sheldon Brown (here), which I think is worth considering:

You don't have to choose once and for all between fixed and freewheel, because the same bike can be both, if you use a reversible "flip-flop" hub.

Many cyclists interested in simplifying consider going to a singlespeed freewheel as a way to "test the waters" with the idea that if they turn out to like that, they might later convert to fixed gear.

This is generally the wrong way to approach it, in my opinion.

I STRONGLY recommend starting out with fixed gear. If it turns out to be a problem, you can easily convert to freewheel later if you want to...but my bet is you won't want to if you give fixed gear a good try (typically takes a couple of weeks of regular riding to get past the strangeness, but then it's quite addictive!)

Most folks who set up their bikes with a fixed/free flip-flop wind up using the fixed gear side pretty much all of the time. The freewheel option is mainly useful for when you have taken a longer-than-usual ride, and need to get home even though you're all tuckered out.

Do you need to carry items and don't like backpacks?

If so a Pearson Touche or another practical fixie frame with rack brazeons is handy. Or you can convert a frame with long dropouts.

I think Genesis may do some practical single speeds too.

I run around in flat Belfast on 48/17 (hills can be tackled with that too if needed...though the cavehill is a bit of work on that...) and I have to say I enjoy cycling fixed over single speed as you can use the rear wheel as a flywheel and adjust your speed for traffic lights. Saves on brake blocks / rim wear too :P

I enjoy cycling fixed over single speed as you can use the rear wheel as a flywheel

Wut?

Apparently not a thing but I'm sure I can feel a difference too, with fixed. You get it up to speed and there's that... inertia? I guess, where it seems happier staying at speed than a geared bike. Like you put effort in to get fast, but then less effort to stay fast.

Apparently not a thing but I'm sure I can feel a difference too, with fixed. You get it up to speed and there's that... inertia? I guess, where it seems happier staying at speed than a geared bike. Like you put effort in to get fast, but then less effort to stay fast.

I suspect that it's because a fixed-gear forces your legs to spin once it's up to speed and, unless you're actively resisting the motion of the pedals, your legs are probably still adding a bit of power. So you're never really coasting.

Pearson Touche

Great tip. I wasn't thinking about (n+1)-ing until I googled that...

Why do you think a fixed bucks you off if you don't relax your legs? The momentum stored in the rear wheel isn't let go by freewheeling so by timing it right you can re-use some of it :)

(no doubt tester can explain this in perfect terms)

Why do you think a fixed bucks you off if you don't relax your legs?

Because the momentum of rear wheel keeps the rest of the drivetrain moving (EDIT: actually the momentum of the whole bike keeps the rear wheel turning, which keeps the drivetrain turning). Why is that particularly relevant?

The momentum stored in the rear wheel isn't let go by freewheeling so by timing it right you can re-use some of it :)

But the momentum of the rear wheel on a freewheeling bike isn't "let go" by freewheeling any more than on a fixed-gear bike. You lose speed due to wind resistance and bearing friction in both systems. The rear wheel of a freewheeling bike is just as much a flywheel as the rear wheel of a fixed-gear bike. The only difference is that on a fixed gear bike you have to maintain the momentum of the drivetrain as well, whereas with gears you stop it with your legs. The fact that you don't even have to think about stopping it on a geared bike is probably indicative of how little momentum the drivetrain is carrying compared to the whole of the rest of the bike.

"The rear wheel of a freewheeling bike is just as much a flywheel as the rear wheel of a fixed-gear bike."

Yes that's correct, I agree that's an oversight on my part.

But on geared bike: Bike momentum does not carry through drivetrain onto you as you can freewheel. If you stop pedalling, the freewheel kicks in. If you then want to stop, you have to brake
On fixed wheel: No freewheel. So the momentum of the bicycle gets carried forward into you via your legs. So either you relax if you want to slow down, and let friction/weight of your legs do it's job, actively resist with weight/muscle strength by standing up or get bucked off the bike.

I find by timing things you can use a little bit of this momentum. If you are slowly rolling but still going you can use it to restart, on a freewheel not so much. That's of course my subjective experience...physics may prove me wrong.

Awesome pub science going on in here.

Fun.

And it's cheap, less mass, mechanical losses and aerodynamics.

#pubscience