Cycling units

[Charlotte]

Why do most cyclists prefer their distance to be measured in Kilometres but their gear ratios in inches?

Given that so many wheels are 700c these days, I don't think I've ever heard of gear centimetres (although to be fair, Sheldon's unitless gain ratio does come close...)

[rower40]

Cateye have a very strange approach to units:

If you configure your speedo to be in Miles, then the clock is in a 12-hour format. ("1pm")
If you configure your speedo to be in Km, then the clock is in a 24-hour format. ("1300")

I like miles.  All UK's roadsigns are in miles and MPH.  But I'll use metres for "just down the road" kinds of spoken directions.

[Julian]

*sings*

Cos my bicycle's half English, and I'm half English too...

[clarion]

For such a fan of retro, I am a keen advocate of metric units.

But I learned about gear ratios in inches, and it's hard to get a new set of figures in my head.

Similarly, seat tubes will pretty much be in inches too, though I've learned that 22" is roughly equivalent to 56cm.  When it comes to compact frames, or USAnian manufacturers sizing in Small, Medium & Large, I am lost.

[Biggsy]

Why do most cyclists prefer their distance to be measured in Kilometres

Not me!  I only use km when in a country with road signs in km.

but their gear ratios in inches?

It's what I'm used to, and you get nice chunky numbers with it.  It doesn't really matter what the numbers actually mean when comparing one gear to another in proportional terms.  That's the usual use of gear inches (or gear centimeters if you prefer), rather than actually working out the distance travelled per rev.

[bobb]

Why do most cyclists prefer their distance to be measured in Kilometres but their gear ratios in inches?

Only odd people measure their distance in kilometres. They are easily spotted as they're usually very old and members of some establishment that I believe is called AUK or something like that.

As a BRITON I generally use only imperial measurements. But I do slip up occasionally and use that new fangled metric shit......

[Chris S]

I only ever use Kilometres for distance these days.

I tend to quote gear size on my bikes in terms of ratios - eg: 49/16 as it's easier to visualise and not confused by tyre, crank or wheel size.

[clarion]

The rules on gearing allowed for youth racing are all in development, which is logical, I suppose, but annoying to use.  The Club have a piece of rope with tape on it at the various marks, and wheel bikes backwards along it till the cranks have done a full turn to measure.

TGL wouldn't be allowed to use his big ring at all, and the two smallest sprockets with the small ring, ftr.

I'm not a member of AUK, btw, bobb

[bobb]

I'm not a member of AUK, btw, bobb

That is weird, because you're both odd and old!! 

[L CC]

Kms give bigger numbers so make it seem better- ie racing along at 35 is great, ditto covering 10,000 klicks. Gear inches is just odd, a freaky sub culture language.

[clarion]

I'm not a member of AUK, btw, bobb

That is weird, because you're both odd and old!! 

[jogler]

gear ratios are easy,ok,hard

[Andrij]

I measure distance in kilometres, despite my US upbringing.

As for gear inches, I don't really care.  I have no idea what ranges my bikes have, just that on hilly rides neither bike has low enough gears.

[citoyen]

Cateye have a very strange approach to units:

If you configure your speedo to be in Miles, then the clock is in a 12-hour format. ("1pm")
If you configure your speedo to be in Km, then the clock is in a 24-hour format. ("1300")

I've always assumed that was because they reckon if you want to use kilometres, you must be French.

I only started using kilometres to measure ride distances when I got into audaxing (I don't mind being called odd, but I'm not old!), but now I've got into the habit of using kilometres for all cycling.

Still use miles for driving though, largely because my car odometer and speedo are configured that way and it would be more trouble than it's worth to get them changed. I did have the satnav set to km for a while but I found it confusing.

I also drink my beer by the pint. If pubs started serving beer by the half-litre, I wouldn't object as long as they charged proportionally less than they do for a pint.

d.

[delthebike]

OS maps are metric. Gear inches is historic, how big is your penny? Gear development is Euroforrin and may be easier to explain gear size to some people.

[mattc]

Gear ratios in inches[effective diameter-ish] or distance-per-revolution give you the same information (as long as you understand which unit you're using!). cog sizes are irrelevant, they're just different ways of achieving a particular overall ratio. It's irrelevant whether you use metric or imperial, because to produce speed you need to multiply by another arbitrary unit anyway (cadence).

Inches are good because:
- you get nice manageable numbers (30-130 or so)
- there is no point in changing to something noone has a feel for.

[Biggsy]

I tend to quote gear size on my bikes in terms of ratios - eg: 49/16 as it's easier to visualise and not confused by tyre, crank or wheel size.

Yebut if you want to compare 49/16 to 48/17, you'll convert them to single numbers.  83" and 76" are simpler to deal with and remember than 3.06 and 2.82.  Including the tyre size is good for comparing the effects of the same sprockets on different bikes as well.

[Polar Bear]

Before I knew about 'inches', I used to make a table of ratios by dividing front by rear.   Thus I'd get a table telling me where the duplicates and crossovers were within the ranges.   In fact, I still do.

[border-rider]

I tend to quote gear size on my bikes in terms of ratios - eg: 49/16 as it's easier to visualise and not confused by tyre, crank or wheel size.

Yebut if you want to compare 49/16 to 48/17, you'll convert them to single numbers.  83" and 76" are simpler to deal with and remember than 3.06 and 2.82.  Including the tyre size is good for comparing the effects of the same sprockets on different bikes as well.

I can never remember the exact ratios on all my bikes, and I don't carry the tyre dimensions in my head either. If someone asks me about ratios, I'll say something like "44 on the front, 17 on the back, which I think is about 69 inches or so"

[Rhys W]

I spent years getting degrees in science - SI units rule! Imperial units well and truly suck - multiples of 12, 14, 3 - why? 10x more of something or 1/10th of something is much easier to deal with. Also, cycling is a European sport, so when I hear/read about "speeds of 80km/h" or "10km to go" it's good to have direct experience of the same units.

Gear inches - what a joke! It's easy to visualize how far your wheel rolls along for one pedal revolution compared to trying to imagine how hard it would be to pedal a bloody penny farthing of specific wheel size.

[tom_e]

I use kilometres just because the numbers come out bigger that way.  No shame, me.  

The gear ratios thing is funny, because people know a gear more as a sensation than a physical thing you can point at or imagine.  So you're entirely comparing to what you remember of past gears and their numbers.  Thus, changing units is a pain, and the oldest unit wins out.  (I've switched to gain ratios, but bent riders are always going to be awkward buggers)

[mattc]

I spent years getting degrees in science - SI units rule! Imperial units well and truly suck - multiples of 12, 14, 3 - why? 10x more of something or 1/10th of something is much easier to deal with. Also, cycling is a European sport, so when I hear/read about "speeds of 80km/h" or "10km to go" it's good to have direct experience of the same units.

Gear inches - what a joke! It's easy to visualize how far your wheel rolls along for one pedal revolution compared to trying to imagine how hard it would be to pedal a bloody penny farthing of specific wheel size.

yes but folks say 63" not 5'3", so that's not a problem!

Your wheel-rolls-along thing is just a case of multiplying by a constant, so it doesn't affect anything - it's only an issue if you only ride your bike one pedal revolution at a time!

[Biggsy]

Gear inches - what a joke! It's easy to visualize how far your wheel rolls along for one pedal revolution compared to trying to imagine how hard it would be to pedal a bloody penny farthing of specific wheel size.

I'm not interested in visualizing how far the wheel rolls for one pedal revolution.  I just want a nice chunky number for comparing how a chainring, sprocket and tyre combination on one bike compares with another, for instance.

[andygates]

Inches are good because:
- you get nice manageable numbers (30-130 or so)
- there is no point in changing to something noone has a feel for.

This.

I generally use miles for day-to-day stuff (it's on the signposts, after all) and kilometres when in Europe or when doing triathlon stuff -- all tri distances are in km, so it makes sense to think in km when tri'ing.

This sometimes catches me out.  Burnham has a 20km bike leg, and last year I mis-converted that to 16 miles on the speedo, with the result that I was startled at how soon I finished!   

[TheLurker]

Why do most cyclists prefer their distance to be measured in Kilometres but their gear ratios in inches?

Because we're naturally contrary;  n cyclists => n² opinions/beliefs.