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Gear Ratio Advice

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Singlespeed & Fixed Gear "I still feel that variable gears are only for people over forty-five. Isn't it better to triumph by the strength of your muscles than by the artifice of a derailer? We are getting soft...As for me, give me a fixed gear!"-- Henri Desgrange (31 January 1865 - 16 August 1940)

Gear Ratio Advice

Old 03-21-20, 05:26 PM
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MajorMajor
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Gear Ratio Advice

Hi All,


I'm new to fixed gear riding and I'm looking to find an 'all-rounder' gear ratio for my soon to be new bike, that I can use for climbing but not spin out on the flats. This may be an oxymoron, but I have no point of reference, so I'm looking for some anecdotal advice.


A bit of background, I commute to work in the UK (Sheffield area) every day, it's a 60km round trip with 1000m of climbing which I've done for around 14 months. I lived abroad for a long time (in a relatively dry climate) and have just experienced my first British winter, which destroyed my very nice road bike. Frankly, I'm not a maintenance kind of guy and I really like riding whatever the weather, which appears to be a problem in the UK.


I'm a pretty strong rider and don't mind grinding in the hills if I can get some speed up on the flats.


For reference, max gradient is 9.3% and one of the climbs is 4.4km at 5% Avg.


Would any of you be kind enough to offer some insight and maybe a few ratio suggestions?
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Old 03-21-20, 06:04 PM
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If you want some of the simplicity of a single speed bike, want to climb hills and still get up some speed, I'd get be using a 3 speed Internal gear hub. Otherwise with 1 speed you might need a 40T chainring with an 18T sprocket or about 58 gear inches for your ride. A 16T sprocket, or about 65 gear inches is good for most rides, But you have special needs.

Last edited by xroadcharlie; 03-23-20 at 11:50 AM.
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Old 03-21-20, 06:11 PM
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Excellent post from a primer thread that is sadly no longer a sticky: puppypilgrim

Uncle Sixty's Gearing Primer for Newbs
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Old 03-22-20, 02:53 AM
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Originally Posted by MajorMajor View Post
Hi All,
A bit of background, I commute to work in the UK (Sheffield area) every day, it's a 60km round trip with 1000m of climbing which I've done for around 14 months.

I'm a pretty strong rider and don't mind grinding in the hills if I can get some speed up on the flats.
I know Sheffield. I doubt there's one gear that can get you comfortably up those hills and which you can spin down the same hills.

However, the answer t your question is easy for you to find: you do the ride every day, 60 km round trip.

Choose a gear which is somewhere around your height in inches and make yourself a promise not to change gear for your entire round trip.

if you can achieve this, then ask yourself whether you think you could do it one gear higher.

If you can't achieve it, then you need a lower gear.

Thus, over the course of a week, you will find either:

1) That one particular ratio works for you, or
2) You need gears.

Once you've found one particular ratio that works for you, you can achieve that ratio, or a close approximation, many different ways by varying the size of the chainring and sprocket. (Theoretically, also by changing the wheel diameter, but I don't think we need to go there!)

Gear ratio in inches is:

Number of teeth on the chain ring, divided by the number of teeth on the sprocket, multiplied by the diameter of the wheel in inches.

A good starting point is around 65 to 70 inches for mixed riding. More if you like to crunch the pedals, less if you like to spin.

Remember that if you need to set off uphill from a red traffic light, there is a limit to how much torque you can apply. (Yes, bikes should stop at red traffic lights.)

If you're dead set on the single speed thing, you may want to consider a flip flop hub with a lower gear for your commute one way (more uphill) and the higher gear for your return journey (more downhill). You can usually get away with 1 or 2 teeth difference and take up the slack in the chain.

It's easier to learn to spin a low gear faster than to develop the power to push a high gear harder.
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Old 03-22-20, 06:33 AM
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Well, are you going to ride brakeless​​​​​​? If you are, I suggest you to start low, so you can slow down and lock your rear wheel easier, also, people here will recommend you a 48-49 chain ring but I think 50+ look better plus bigger cog and chain ring means less wear.
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Old 03-22-20, 08:29 PM
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Sturmey S3X is a great choice for varied terrain, especially hills. It'd get you two climbing ratios and one for the descent.
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Old 03-27-20, 11:50 PM
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Start with 48 or 47/ 18, and find your balance from there, 1t at a time? Not sure if you can tackle the 9% climb comfortably tho. Thing is you can't go too low since there's that whole flat distance u need to cover, or you'll end up spinning to & fro work daily, which may kill the riding fun. Considering the amount of descends, you'll need brakes too; skids consumes too much energy. Unless you can get that 15mins nap at midday daily.

I recently changed fr 48/17 to 49/17; and my hips can tell the difference immediately. That 1t change is quite noticeable. Good luck!
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Old 03-30-20, 08:59 AM
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Howdy mate,
I am not familiar with Sheffield but my home town of Omaha Nebraska is hilly in spots. I ride 44/17 on 40mm tires(tyres). I've been riding fixed 3 years and recently geared down because while I was able mash up most any hill my knees started to protest. 44/16 to 44/17 has been a small adjustment that has saved my knees and made my riding all that much more enjoyable. I geared down this winter while playing with bigger tires, going from 28mm to studded and eventually 40mm slicks now; bigger tire bigger gear. Im really pleased with the plush ride of the 40mm tires so I think i'll stay with 44/17 a while even if I spin out easier, i'm learning to spin now so spinning out less, it's a win win all around. If you haven't heard this yet: spin to win.
You can always pull feet off the pedals on the down hill!
best of luck from the other side of the pond
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Old 03-30-20, 09:14 AM
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When I first started riding fixed I bought three chainrings 44-45-46 and a miche cog carrier with 16-17-18T cogs which gives a pretty good range of options, and you can play around with it to find what works for you.
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Old 03-30-20, 11:25 AM
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First, my background on fix gears. I raced road in the 70s. First year, the club vets told me to set my second bike up fix gear to learn to pedal smoothly. Crashed first ride when I tried to coast but got home sold! I've had fix gears ever since and known for 40 years that if I had to slim my collection to one bike, it would be a fix gear. Now, I love to climb out of the saddle and always have. I raced New England on a 42-19 for everything but the Stowe race up Smuggler's Notch. I've ridden up and down Mt Diablo in California fixed.

So, horn tooted, my advice - 1) get really comfortable with the idea of lugging huge gears uphill and tossing concepts like RPM out the window. Learn to relax as best you can while straining every muscle. I call it "loafing". I've loafed up Portland, OR's Germantown Rd in a 44-17 on a 27 pound bike. Watch your breathing, If it gets too high, slow down. (Oh, and yes, you will need REALLY GOOD pedal retention. You will be pulling up for all you are worth. I use old fashioned toeclips and quality leather straps, I'll talk more about this in the downhill part.

2) Downhilll. This decides the gear just as much as the uphill does. Use brakes! I have always had really good ones front and rear. Brakes with lots of modulation are preferred. My commuter fix gears have always run Mafac Racers. I've been using dual pivots and V-brake levers on my mountain capable fix gears (where I stop and change gears; but always fixed, no single speed freewheel). The dual pivot and V-brake lever setup doesn't modulate in the lever travel sense but it does a lot in the lever pressure sense. The panic lever grab when I just saw there was no way I was getting around that blind corner without a hard pedal strike? Well, the adrenaline fueled lever grab just slows me a whole bunch, no lockup and nothing funky happening at all.

With brakes, you can focus on simply spinning as fast and smoothly as you can. Now, you will have lost the ability to know whether your feet are straight or crooked on the pedals and you have no business looking down and back at 40 mph and (say) 200 RPM. Back to those toeclips. Retention! You never want a foot to come off. (If one does, yank the other out instantly and ride like a clown, both feet out to the sides. If a pedal strikes your foot, ankle or calf, we're talking life long injuries; like you just put it in front of an industrial pile driver. Pedal is being driver through a gear reduction by all of your combined weight. It won't even slow when it hits you. (Anything that tries to stop the pedals will break. Keep your clothes, shoes and shoelaces nice and trim. They might not rip before sucking your foot in.) So - I ride downhill with cycling shoes, the old fashioned aluminum slotted cleats, straps pulled tight and clips, just like bike racers did a million years ago and for the exact same reasons. I mentioned not being able to tell the angle of my foot when going fast. Yes - and I have pulled my cleat out a few times going down hill. But, the big "but", my foot is still in the straps and I know instantly that my cleat is out. Heart rate jumps to astronomical and I grab those (nicely modulated) brakes and slow a bit. Slide foot forward and cleat back in, HR comes down and all is good. (For really good old fashioned cleats - Exustar track cleats. ~$20 US. Fits LOOK pattern 3-bolt shoes.)

So I haven't answered your gear question yet. But you can see it's a balancing act. And it depends on the relationship of your inherent and to-be-learned leg speed and inherent and to-be-trained-on power to lug-uphill. For me, gears like 42-17, 44-17, 42-16 work out best.

Clothing advice - wear cycling shorts that keep everything in place! My ride down Mt Diable was done while traveling the country looking for work. Beater bike, beater clothes. Old saggy shorts. Felt like my personals had stood in for a punching bag at the gym.

You mentioned poor roads. Steepish (and fast) descents. High RPM. This adds up to lots of visual vibration! "Seeing" the road surface downhill is a LOT harder. You hit stuff. Hard rim hits on pothole edges happen (And you cannot "hop" the rear wheel over anything. You can un-weight it IF you see the obstacle but that's all you can do.) Want to have a wheel that allows you to just roll to a stop, change the tire and ride on after that hard hit? Ride tubulars! Seriously! They'll save your butt. Tubulars often don't flat, even on hits that dent the rim an inch (done it three times). And - the skin saver - slowing a flatted tubular from high speed is not a big deal. Properly glued. they stay on, always. (I used Tubasti, the glue that doesn't set up hard and never cleaned rims. The more build-up, the better, New rims scared me. And you can do reasonably secure road changes without messing with glue. And you CAN get that tire off with your hands. I have about 60,000 icident free miles of fix gear ridng with that glue. I haven't seen it for years n this country but I'm sure its still being made.) 10 years ago I flatted in back at 25 mph with clinchers. Tire came off, jammed in the seatstays, tossed me and I suffered cracked ribs, broken collarbone, and acre of road rash and a hard helmet hit. Flatting in front at 40 with a tubular is far less exciting.

Now, in my 45 years of fixed gear riding, I've gotten older. I cannot/am no longer willing to ride the extremes. To keep riding fix gear and be able to (reasonably) be able to ride where I love, the hills, I had a custom bike made that facilitates using flip-flop wheels and fast wheel flips/ Also made a 1 lb chainwhip that straps to the top tube. So now I cheat and go as low as 42-24 and as high as 42-12. Same gears as always on the flatter stuff and quick hills. And always fixed. Never owned a single FW, not since I was 11 and got my first 3-speed. (Didn't discover the fixed gear until I was 23.)

Ben
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