Road Cycling - 53- vs. 52-tooth chain ring

My 53-tooth chain ring feels like overkill. I hardly ever use the large chain ring because it's usually too hard to pedal. Even going downhill with a tailwind, I still never use the smallest rear cog. To make the 53 easy enough on flat terrain, I have to shift to the inner cogs which crosses the chain too much.

I would like a smaller chain ring that will be more functional. Will switching from a 53 to a 52-tooth ring make any appreciable difference? One tooth doesn't seem like much, but maybe it has an effect. I see 52 as the only other choice besides 53 listed in the Nashbar catalog for Shimano 105 chain rings.

condor

No,but a 48or 50 will.There are other aftermarket rings.Checkwww.branfordbike.com

You can work out the exact chainring size you need.
Look at the gear combination you want as your max.
53x T where T is no of teeth on rear cog

Work out the total gear "size" in gear inches

G=(53/T )x 27

(27 is the size in inches of your rear wheel.)

Calculate the chainring size which will give the same G with your biggest rear cog. eg for a 28 tooth cog

Chainring size= (G*28)/27

No guesswork involved.
If you get a smaller chainring such as 48, you may want to consider getting a smaller inner, such as a 36. This will give you some useful climbing ratios.

I like to solve these kinds of questions by figuring out what it means in speed and cadence.

If your highest gear is a 53-12, and you have a cadence of 100 rpms (pretty high), then you'll go about 55.5 kmh (34.5 mph). If you switch to a 52, then 100 rpms will put you at about 54.5kmh (33.9 mph). Switching to a 48 will put you at about 50.3 kmh (31.2).

I am with Michael, if you go with a 48, then change your small ring to a 36, to give yourself a sufficient spread between the big and small rings. Then you'll be able to climb anything around with nice high cadences.

Lot's of folks are "over-geared", i.e. they have big gears that they never use. I could use something bigger than my 52-14 for that occasional high-speed descent. But, more importantly, I would love to exchange my 42 small ring for a 39. Alas, on my old bike, a 41 is the smallest that fits (a new crankset would not be worth it).

Cheers,
Jamie

You'll almost never see a bike specced with 52/39 out of the shop. There's an old superstition about unlucky 13-tooth gaps that bike companies generally respect.

48/39 and 48/38 are pretty common chainring combinations for cyclocross, so you should have little problems finding a 48. 50 just doesn't have a huge amount of demand, so it's a little harder to find.

What's the story behind the superstition? What happens to you if you violate it? Horns? Warts? Testicular Cancer? (Quick, someone figure out L.A.'s gearing from the early part of his career.)

Cheers,
Jamie

Hey JMLEE..........He cant put a 36 small ring on a 130BCD. 38 is the smallest. Workable if he's got a 110bcd,but he did not say.

Originally posted by jmlee
What's the story behind the superstition? What happens to you if you violate it?
Actually, I think it's just a generalized bad luck thing.

Originally posted by velocipedio
You'll almost never see a bike specced with 52/39 out of the shop. There's an old superstition about unlucky 13-tooth gaps that bike companies generally respect.


LoL, somehow USA Cycling had no idea about this when they made max junior gearing 52/14! Every junior in the U.S. rides that combination. Which means most ride 52/39 chainrings! :eek:

Any 130 mm bolt circle diameter (BCD) chainring will work. Harriscyclery.com has a big selection of individual chainrings.

FWIW, I use 48/34 up front, but I have 110 BCD crankset.
Regards,
Raymond

Well, here's my 1 1/2 cents...

I have a 52/39, and I have a 14 - (I believe) 29 T 6-speed freewheel set. I can keep up a decent cadence (~95 RPM) w/o worries.

BTW- I believe the 13T diff thing- I just started getting into racing in late June, and so I picked up a used bike then. One bad freewheel, shredded bottom bracket bearings, and stripped crankarm threads later, I'm on my 2nd used racer- that my local bike doc sez will soon be run into the ground, needing a 3rd bike in less than, at the most, 2 years. My second racer was fine until I replaced the 52/42 Biopace chainrings w/ 52/39 Ultegra; my 1st bike had 52/39.