42x18
 

Hey guys, I recently got a single speed and its gear ratio is crazy low at 42x18. This seems lower than most riders, the fixie kids would laugh at me. My first thought was to up the ratio, but im having to spin super fast in order to keep up on the group ride and I wonder if this is good training, I kind of think it is. Does anyone else run a low ratio like this for training purposes? they say spin to win...

Depends on your goal. I ride a 42x16, but that is a touring rig in mountainous/hilly terrain with full load. For mountain bike riding I use a 32x16.
If trying to keep up on a group ride, what gear-inch do you spend most of your time then get a single speed around that and see how you do!
Good luck!

I tend to mash, so I intentionally keep my ratio low on my SS/FG bikes to force myself to spin. It's easier on the knees in town and it's good to get comfortable at a higher cadence out on the road. Typically, I'll do 42x16 for the road FG. My SSCX is at 41x18, which really makes me spin on flat tarmac, but it's as high as I can go on dirt and grass.

Something we discussed recently in this forum is the internal work required to move your legs and feet up and down as you pedal. Your body has to do both the (usually bigger) external work of pushing the pedals plus this internal work.

Turns out that the internal power requirement is independent of the external power delivered to the pedals but strongly dependent (as we would expect) on pedal RPM. This makes sense because it’s just the work we have to do to move the mass of legs, feet, pedals and cranks around as we pedal.

So, we spend more W/kg spinning our legs fast than we do spinning them slow. For example, at 110 RPM, the internal work runs about 1 W/kg, which is already significant and it is a sharply increasing function at this point. By comparison it will only be about 0.1 W/kg at 50 rpm.

So, in addition to protecting knees from greater forces and strain, you will also work your body somewhat harder at a higher cadence (for the same actual speed on the bike).

Otto

Yes - spin to win!

I recently changed my Schwinn road bike from 42/16 (70.9 gear inches) to 40/16 (67.5 gear inches) and I think if anything I’m riding faster and stronger overall at the lower gear.

I made this change to help reduce long term strain on my knees, but it seems to also be just as effective. Also, our trails are a lot rougher after massive flood damage and repairs, so average speeds tend to be down a bit and there is a benefit to slightly lower gears in negotiating those routes.

Thinking about also changing the RockHopper from 42/16 (68.3 gear inches) to 42/17 (64.2 gear inches) and see how that goes.

Otto

Yeah I was really tiring myself spinning like a madman trying to keep up downhill

What singlespeed riding has taught me...

You're always in the wrong gear. Deal with it.

My bike is a road bike fixed with flip flop, set up as 42 x 18/16.

42 x 18 is good all round ratio for on and off road, speed control without braking or skidding, and good for short bursts of up to 28 mph or even 30 mph downhill.

42 x 16 is easier on the downhills, bit less acceleration, not so good off road or up hill.

On a 700c x 28mm, these are not especially low gears. I find myself doing similar average speeds to what I achieve on my 2 x 10 although admittedly that is heavier and less aero.

42/18 is the winter gear on my FG. Usually by this point in the season I've changed it to 45/16, but I haven't gotten around to it yet.

Spin it smoothly at 25+ MPH and people won't be laughing at you, they'll be impressed.

If the kids are laughing at you, you should take it deeply to heart and internalize it heavily.

To those who are looking for serious help and wondering about gear ratios, ride whatever works for you and don't worry about anyone else. It doesn't matter what anyone else rides, it just matters what works best for you and your situation. 42/18 56/15 38/24 or anything in between or outside of that so long as it works well for you.

From talking to people I see on the road it sounds like this is actually a smart training method to up my cadence. Think I might get another single speed to ride in a huge gear for strength training. While training to become a fixie monster I was mashing with a 48x14, not sure how effective grinding in that gear is for training, but I met another dude who said he used to train like that. is grinding on a gear that you can't even spin kind of pointless?

My Swobo Accomplice came with a 42x18. It's a commuting gear. It was my first SS and after a couple of rides I ordered an S300 crankset with a 48T and it's good, my average speed is about the same as on my geared bikes on solo rides. I don't take it on group rides, the gearing would be a little too low for that pace.

I did the change to 42/17 on the RockHopper. It works fine. Same overall speed. Easier on the knees. Not entirely used to the higher cadence but I’ll stick with it. I reckon it will grow on me.

Otto

42 X 18 isn't "crazy low," and if you're even considering what the "fixie kids" will think, you should definitely finish high school.

Fixed gear bikes need bigger gears so you don't spin out on the downhills, but they climb like crap. Lower-geared singlespeeds are much more versatile, IMO.

I live where there are hills, so my SS bikes are 39 X 17 (700c), 40 X 18 (27.5"), and 38 X 16 (26"). I ride with geared riders every week and can keep up just fine.

What are you "training" for? How hilly is your area? Do you actually care if the "fixie kids" laugh at you?

Indeed, are there such things as "fixie kids"?

That was my typical gearing when I was commuting fixed. 14 miles each way, ~800ft climbing. Max rpm on downhill, as calculated by gps speed was 220.

You did 40mph downhill on a fixed gear? Or are your fingers fat?

I hurt my leg today trying to keep up with a group ride, we were going like 25+ on a slight downhill and I was spinning so fast I managed to pull something in my upper thigh/groin. This sucks, since when do you get injured by spinning fast. This bike is a tad small I wonder if that's the reason.

i mention the fixie kids because I am inversing them by riding a smaller gear than I am comfortable with. They all ride in too big of a gear. I'm training to be able to finish the drop rides

Cool story, I guess?

Again for those who actually need help, don't ride a bike that is too small I know it might seem cool or you are aero, bro but in the end get a bike that fits. You don't save money buying a smaller bike and if you are looking to save weight maybe drink one less beer or take a dump before you ride or both or buy a nicer bike.

Brokie Kids for life!

Sounds like you should spend your money on a proper bike fitment first.

If you're a new rider, and they've been riding for a while, there isn't a magic gear ratio that will give you the base miles/fitness. Gear inches is very much preference. If you can't spin, then get a heavier gear. It will be harder to climb with and will be rougher on your knees.

I bought this bike because it was super pretty and 150$, but you are right that its hurting me because its too small

That is a large amount of money. Not for a bike for a bike it can be rather cheap but for something rather useless to you it is expensive. Get something that fits sell this one or strip it for parts if the parts are decent (which for $150 probably not) and buy a frame that fits you better.

Man, I guess I'm at the "really crazy low" end of the spectrum on my ss Cross Check. It's currently running 38x19 (700c x 40 tires). But I ride it like a ss MTB here in the SoCal mountains, so it's all a trade-off. I can clean most singletrack and fireroad climbs I frequent, but I sure do coast a lot elsewhere!