Can't cycle very fast downhill

[ruffstuffbob]

Hi, As I've said before on this forum {I think} going downhill is like eating a piece of chocolate which is left on the tongue to melt and be enjoyed slowly. What's the rush... relax...let gravity take over...[gently feather your brakes to slow yourself down] and enjoy the view [and the rest] unless you've got that train to catch of course!!! Bob.J.

[Trigger]

Well said Bob. I'll be damned if I'm going to rush down a hill in 20 seconds that I've just spent 10 minutes grovelling up.

Downhill is to help me recover for the next uphill, I'd like that period of time to be as long as possible thanks

[Vorpal]

Hmm. Strictly speaking, I think 'cog' is a term for a tooth on a gear wheel and the term is fairly archaic. I think it dates from the days when teeth were slotted individually into a wooden wheel.

It's not really used by engineers these days, as far as I am aware, who would call such things gear teeth. In Horology circles, anything over 20 teeth is called a wheel; anything under 20 is known as a pinion, when the teeth are called 'leaves'. A collection of wheels and pinions would be referred to as gears.

Different types of gears have different types of teeth. A car gear box would have involute gears; an old clock would have cycloidal gears (well, strictly speaking, ogival). The word sprocket also refers to individual teeth designed to mesh with a chain, or some other strip (camera film for example), so we should, to be really pedantic, be talking about a sprocket wheel.

I'll get my coat.
.

Sorry if I wasn't clear. The cog is the driving bit. It might be a 'tooth', like in a gear wheel, a spline, etc. Orginally they were pegs, stuck into wooden wheels, like wagon wheel spokes. The term cog is still used in machine tools, where it is used to differentiate cog sizes or numbers cut by gear cutting machines (which may cut helical gears, splines, key ways, and other sorts of toothy type things).

So, we (or rather our bikes) don't have any cogs. Only sprockets. And the OED says that sprocket can be the toothlike projection, or the wheel (with sprockets) and indicates that the wheel may also be called a sprocket wheel. So it seems that it is not incorrect to use sprocket and sprocket wheel interchangeably; just imprecise.

However, I'll carry on calling my shifting thingies gears, and the front sprockets, chain wheels, 'cos people understand that.

Oh, and I like to freewheel (I don't think we have one of those, either ) down hills and maybe have a drink, so it doesn't look like the climb almost killed me

[beetroot]

I've just calculated that if I could maintain a cadence of 900 rpm I could average 295 mph. Something to work on

[Robert]

I've just calculated that if I could maintain a cadence of 900 rpm I could average 295 mph. Something to work on

That's a very big IF

[alicej]

I've just calculated that if I could maintain a cadence of 900 rpm I could average 295 mph. Something to work on

That's a very big IF

Ooh, be careful, I just read that when it's wet it'd be possible for a bike tyre to aquaplane at about 220mph!

[beetroot]

I've just calculated that if I could maintain a cadence of 900 rpm I could average 295 mph. Something to work on

That's a very big IF

Ooh, be careful, I just read that when it's wet it'd be possible for a bike tyre to aquaplane at about 220mph!

Excellent. All I have to do is combine the aquaplaning with 900rpm and I should be able to reach take off speed and lauch myself into orbit. Anyone able to recommend suitable gearing ratios?

[g00se]

Guys, guys, guys...

All this advice is very helpful, but we've missed a trick here!

New into cycling, enjoying it, want's to keep fit...

This is the perfect excuse to explain the n+1 rule (or the s-1 corollary).

For the OP, n+1 is the correct number of bikes you should own, where 'n' is the number you currently have. So the simplest solution to your chainset related woes is to buy another bike. I think I speak for all, in suggesting a nice new shiny road bike with a 50+ tooth top chainring (though I'm sure others will suggest that once purchased, the n+1 rule dictates that a nice shiny touring bike is in order, to carry all the accessories you're probably be getting too).

And just to clarify, the s-1 rule is the max number of bikes you should own, where 's' the number at which your significant other leaves you / files for divorce...