Gear ratios

[BurningLegs]

Hello all,

I just purchased a new Cyclocross bike as a replacement for my flat bar hyrbid, and I'm hoping it will do me proud on the commute, leisure road riding, and mild trails.

I think my old hybrid had a 50/34 and 12/25 but can't remember exactly.
The new cyclocross is 46/36 and 12/28

The cross bike is my first drop bar bike, and the gears are taking some getting used to! The different action to change gears, and the feel of the gears is quite different. The new bike is heavier than the old one and I think I might be under geared for both climbs and descents (but need to really test myself and confirm)!

I've tried looking for some calculators online to get a feel for how different the gearing is in % terms but haven't found anything. I looked at Sheldon's but it seemed quite complicated and doesn't make a comparison easy.

What calculators do you tend to use, with a focus on making the output clear and preferably with the ability to compare different setups?

 

[Yellow Saddle]

If the wheels on your two bikes are the same, the calculation is very, very simple.

Divide the number of teeth on the front by the number of teeth on the rear. That ratio gives you the number of wheel revolutions per crank revolution. Compare the various ratios you want to compare.

However, you have to ask yourself what you are trying to achieve with such a comparison. Numbers are just, numbers. Your legs will tell you whether you should change to another gear or not.

 

[arch684]

You could get the gear calculator app for your smart phone.Easy to use and will give you all the info you need

 

[theloafer]

@BurningLegs .... http://www.gear-calculator.com/

 

[S-Express]

What calculators do you tend to use, with a focus on making the output clear and preferably with the ability to compare different setups?

Simply ride the new bike some more, and use that as a 'real world' comparison.

 

[Crackle]

Build a spreadsheet and put cadence in it. Then you can compare different wheel sizes and gears at the cadence you might typically ride. You're welcome to try mine or an adjusted version of it. I think it's generally right, someone can tell me if it isn't. It's looking a bit dated with no 29er option or fat bikes or gravel bikes but it's easy enoough to adjust it.

 

[boydj]

The only real difference with the gears is that you should be able to spend more time on the big ring and there will be less of a jump when moving between chain rings. If you are moving really fast, you'll spin out a bit earlier, but I doubt that's a serious consideration in real world cycling.

 

[BurningLegs]

Thanks for all the input guys, I will have a play with some of the resources shared

I totally understand the "ride the bike more to understand the differences" comments - of course, riding the bike more will tell me everything I need to know about this bike. But it would be nice to feel like I understand the theory and numbers as well as the feel. A couple of people have mentioned that they know how a particular gear 'feels' - I don't get that at all on any bike right now, and I think that is because all I do is ride and don't pay much/any attention to what gears I'm using, I just work through them as needed. Ignorance is bliss, hehe, but I'd prefer to have at least some understanding.

 

[ColinJ]

I had very similar gear ratios on my CAADX when I bought it (46/36 and 12-30). We have some very tough offroad climbs in Yorkshire and Lancashire and I felt overgeared on them in 36/30 so I changed the small ring to a 34 and put a 12-36 MTB cassette on to give a much nicer 34/36 grovelling gear. I needed to swap my 10-speed rear mech for a 9-speed MTB rear mech to get it work; it sounds odd but it works!

 

[cyberknight]

You get used to what gear you ride in at certain speeds and how fast your pedaling to do so,the mistake most people make is to pedal a "fast" gear slowly.90 rpm is supposedly the most efficient with leeway either way for personal preference.
My winter commuter drop bar MTB has 48 big ring with 12_25 and the road bike has a 50 with the same,for the same speed I gereally use one gear faster at the back for the same speed if that makes sense although I tend to just use the same at the back and go slightly slower as the bike weighs a lot more ,like 5kgs more so it takes so effort to get going g and hills......

 

[nickyboy]

Your lowest gear on the old bike was 34/25 and the lowest on your new bike is 36/28

36/28 is a smaller number than 34/25 so your new bike's bottom gear is easier than the old bike's so not sure why you would feel a problem going uphill. Going downhill your top gear was 50/12 and is now 46/12 so if you're going fast downhill then you may feel you haven't got a high enough gear on your new bike compared to the old one

Your old easiest gear of 34/25 is probably similar to the second easiest on your new bike

 

[Crackle]

I personally never know what gear I'm riding in. I roughly know from my cadence and speed where I am on the block but I'm not really bothered which gear that might be. I used to ride quite differently but the advent of 10 speed blocks and brifters and a change in riding style meant I know longer consciously keep track. Instead I used the spreadsheet I created to design the ratios I needed and then bought the chainrings/cassette to suit. I must have got it right because for most circumstances I don't move off my chosen middle ring and the rear cassette shows the most use in the middle of the range. There are lots of ways to do the same thing, so it's a question of choosing what suits.

 

[SpokeyDokey]

@BurningLegs

http://www.bikecalc.com/gear_ratios

 

[freiston]

I personally never know what gear I'm riding in. I roughly know from my cadence and speed where I am on the block but I'm not really bothered which gear that might be. I used to ride quite differently but the advent of 10 speed blocks and brifters and a change in riding style meant I know longer consciously keep track. Instead I used the spreadsheet I created to design the ratios I needed and then bought the chainrings/cassette to suit. I must have got it right because for most circumstances I don't move off my chosen middle ring and the rear cassette shows the most use in the middle of the range. There are lots of ways to do the same thing, so it's a question of choosing what suits.

I don't keep track of what gear I am in either and similarly, I'm not really bothered except when I think I've got a lower gear available on the cassette but I haven't

I've been expressing gears as gear-inches for decades and for me it works as a 'quantifier' (but even now, I still get an image in my head of a penny farthing with a front-wheel diameter same as the gear-inch). The gear-calculator that #theloafer linked to is my online calculator of choice and it gives lots of options for displaying/comparing gears, including speed at a particular cadence.

Things might change, but as things are, in my experience, gear-inches are a 'common language' when talking bicycle gears, and when you start working your inches out and using them as a quantifier, they soon become second nature for thinking and discussing gears.

 

[Tigerbiten]

Converting gear inches to speed is easy when you remember .......
If you spin a 100" gear at a cadence of 100 rpm then you'll be doing 30 mph.

As for how fast I'm going in each gear, I've done enough miles so I roughly know. 1st, ~2mph. 12th, ~10mph. 17th, ~20mph, 20th, ~30mph, 24th (top), +40mph, I've a silly big range of gears ........