Tribabe

I'm a newbie who's been asked by an equally clueless friend to help choose his gears for a new bike. I'm a 5 ft 2 female with a custom built 48 cm titanium frame, 650c tyres and 53-39, 12-27 gear combinations which I found easy when climbing. My friend is a male with a 49 cm Look 585 frame, 700 c tyres and has been advised by an experienced rider to go for 53-39 and 12-25 gear combinations. Having tried 700c tyres and 12-25 gears on undulating terrain on my old bike, I found my 12-27s a huge relief on those climbs and advised my friend to get the 12-27.

Am I giving the right advice? TIA for all your replies.

Cheers from Sunny Singapore!

Applehead57

If you live in a hilly area, 12x25 is just not enough, UNLESS you are strong cyclist.
(Alot of cyclists will debate that point, but they are wrong).
I'm now running 12x28, not alot of difference, but after 5 months of winter, very helpful to regain leg strength.

Matt Gaunt

I run triple it's so hilly where I ride. But I have 12-27 cassettes because if I don't want to bail to the granny cog I can still get up hills.

12-27 is fine on a 53-39.

sydney

your 650 wheels also give you a bit lower gearing compared to 700c wheels. Noone really knows what someone else really needs. If in doubt,go with the lower gearing.

Sheldon Brown

Gearing is a very personal matter, and it is difficult to give good specific recommendations for someone you haven't actually ridden with.

The gearing need depends on a large number of variables, including:

•Your weight
•Your strength
•Your endurance
•How far you'll be riding in a day
•How hard you're willing to push
•How much baggage you'll be carrying
•The steepness of the terrain
•The nature of the road surface

There is no magic formula for this, only experimentation will let a rider determine what gearing suits his/her needs.

You might find my Online Gear Calculator helpful for this.

Sheldon "Gain Ratio" Brown

CdCf

I just upgraded my bike and got a low gear of 15.8 effective gear inches (16.8 nominal). I still can't spin up steep hills, so I wouldn't mind an even lower gear.
8-10 GI maybe...
But 13 is probably the lowest possible, and that requires a 19 chainring (don't think they come any smaller) and a 34 on the cassette.

neil0502

Dear Tribabe-

Since you appear to be new to BF . . .

I don't know about your computer, but on mine, whenever Sheldon Brown posts, an organ chord plays. It's kind of like Church.

IOW: you've just had a visit from "The Man." Heed his words. For gearing advice, it's also a good idea to work closely with your LBS. They'll be well versed in the terrain that your friend will actually be riding, and well positioned to assess his capabilities.

Good luck!

capwater

Invest in a chain whip and lock ring tool. That way if you want to swap out cassettes it's a snap. Depending on terrain or if you use the same wheels to train and race in the cost of an extra cassette in a different configuration ain't a big deal.

HiYoSilver

What is a chain whip and lock ring tool? sounds interesting.

Generally 12-23 x 30-42-52 is not enough for good hills. 12-27 might do it and still keep smoothness. 12-31 will definitely handle hills, but at the cost of smoothness. This is with a 9 speed. I don't know about the 10 speeds. I think they just add a gear in the middle so you don't gain anything at the ends.

neil0502

https://www.icyclesusa.com/catalog/to...chain-whip.htm

https://www.parktool.com/tool_indexes/catindex_fr.shtml

sydney

Nonsense. a 30x23 is my hill gear. Many don't need that much. Many need more.Some need alot more. Therefore it's impossible to gneralize,especially with no info...Where can I get a 31 cog?...that sounds interesting.

biker7

Good advice Cap...my Park whip and cassette removal tool are coming from Nashbar in the next couple of days. I have been in contact with Branford and may purchase a 12 tooth no.1 cog and 13 tooth no.2 cog to widen out my 13-26 Campy 10 speed cassette. I found out that I can't just pull a middle cog and push the existing 13 tooth cog back one position and only replace the outboard no.1 cog. I will likely pull my 18 tooth cog and buy a new no. 1 & 2 cog. I want to run a 12-26 cassette to widen my gearing mostly when using my middle 42 tooth chain ring and make the 30T granny which I virtually never use a bit more useable. Anybody know if Branford is the best place to purchase separate Campy rear cassette cogs?
Thanks,
George

HiYoSilver

The 12x doesn't matter for low end. So let's look at the low end, the x25 or x28 on 700c tires.

ROAD BIKE: 30t chainring
x23 == 35 inches per revolution [ gear inches ]
x25 == 32
x28 == 27
x32 == 25

TOURING BIKE: 26t chainring
x25 == 28 inches
x28 == 25 inches
x32 == 21 inches

Touring riders are usually in good shape and what they ride will handle any hill for similar riders. Since you are not a touring rider and assuming you have hills, your target should probably be 25 to 27 inches. Test a bike with 25 inches on a good hill and see if it is low enough for you. If not, then you'll have to change out the chainrings to get smaller rings. From personal experience 35 inches is way too high for good hills.

sydney

35 works for me.Many would scoff at anything lower than a 39x 23. Again,that business about generaliztions. Maybe some people need to eat more spinach,train harder and ditch the extra donuts and Big Macs? FWIW, touring riders are alos lugging a heavy bike ,lots of stuff and wider heavier tires.

HiYoSilver

Ok, the 31t was a typo, or brain fart.

Tribabe said she was a newbie. I don't remember the diameter of a 650c wheel in inches. If it was a 700c, 39x27 == 39 gi. So it's probably in the neighborhood of 35 gi. That being the case 30x23 would work for her and her friend if they are in the same shape.

I currently ride a 30x23 low gear and it's a tad too high for me. My problem is the low is too high and the high is too low and I haven't figured out any method of keeping easy gear progressions while adding more low end and more high end gears.

You can eat and train all you want, but the ticking clock means at some point you need different gears.

sydney

My clock has likely ticked longer than most.

sydney

They have doubles with a 39, not triples with a 30. My preference however is for triples with a 39 middle and 30 granny.Gets low enough gears and close cog spacing.

rmwun54

Depending on your age and fitness for cycling, to be on the safe side 12-27 is fine if you are not riding overly aggressive. Easier on the knees when faced with challenging hill climbs. But if your friend is a decent rider and plans to ride consistantly a lot 12-25 is enough. Personally I love 12-27 and I am in pretty good shape and do have a 12-25 set up, but I decided that I rather spin and save my knees on big hills using the 27.

Tribabe

THank you all for your replies. I'm in my mid thirties and fairly fit as I've been training with a triathlon company for the past 4 months and have done quite a few long rides on undulating terrain in neighbouring countries. Still, I find my 12-27s such a welcome relief from my old 12-25s.

My friend is in his mid to late 40s, not an experienced rider, and completely new to road biking. THe only time we rode together was up some fairly steep and long slopes with him on a mountain bike and me on my old roadbike with the 12-25s. I had no problem going up the slopes but he was almost blue in the face when we got to the top - that experienced converted him to road bikes. It's not terribly hilly in Singapore, but I reckon if he plans to ride in the neighbouring countries where it's quite hilly, he ought perhaps to play it safe and get the 12-27s. I've got Shimano 10 speed Ultegras and he's planning on getting the same.

biker7

Your friend is likely a better candidate for a triple or compact double with a 12-27 than yourself.
Good Luck,
George

Al1943

Easy enough, start with a 32 or 34, and one Dremel tool.

Al

Al1943

If you do the math, going from 700 to 650 wheels is similar to reducing your chainrings by 2 teeth each.
And that could be a good thing, more climbing power and less weight.

Al

Avalanche325

Something you won't need if you choose the correct gears to start with.

(Note: professional racers are exempt, they often change gears for the terrain)

juicemouse

I'd definitely opt for the 12x27 in his case. In general, I think it would be wise for any inexperienced cyclist to go with a bigger rear cog, as they can always switch it out for a smaller one for their next cassette. The only thing you'd be giving up over the 12x25 is slightly smaller jumps between the biggest gears on the cassette, which is really no big deal at all, especially with a 10s drivetrain.

DogBoy

I'd vote for the 12-27 also, especially if this is a 10-sp bike. BTW, I don't think you can go higher than a 27 cog with a shimano road rear derailleur, so going higher means changing derailleurs and cogsets = pricy.