1,2 or 3 chainwheels?

[talisman50082]

Thanks. The ratio method makes more sense to me at the moment. I have to think," chainwheel 1 rev , rear cog 2 revs x wheel of 27 = 54 etc. Even then im not experienced enough to relate to the effort involved ,well not immediately lol.

 

[Gravity Aided]

The number arrived at is known as the development number, representing , as 54 does, forward inches of travel, and can be used as a comparison, so you know that if you have several gear combinations adding up to the same number, or very close to the same number, that gearing won't work for you, because many of your gears would be the same, just in different combinations. (Hope I am not explaining how to suck eggs here).

 

[Nigelnaturist]

Thanks. The ratio method makes more sense to me at the moment. I have to think," chainwheel 1 rev , rear cog 2 revs x wheel of 27 = 54 etc. Even then im not experienced enough to relate to the effort involved ,well not immediately lol.

I will do a ratio one for you perhaps in the morning, having a few issues with a hard drive at the mo.

 

[slowmotion]

Triples tend not to change gear as crisply as compacts/doubles, the reason being that the cage on the rear derailler has to be longer (to take up the extra chain length). The longer cage is usually a bit more flexible than a short one, so things get a bit "spongy". How fast the gears change is not entirely important to people like me. If you need some low gearing to get up hills (and I do), get a triple. You may look like a hamster on a wheel, but you may have the personal triumph of not walking.

 

[Nigelnaturist]

Triples tend not to change gear as crisply as compacts/doubles, the reason being that the cage on the rear derailler has to be longer (to take up the extra chain length). The longer cage is usually a bit more flexible than a short one, so things get a bit "spongy". How fast the gears change is not entirely important to people like me. If you need some low gearing to get up hills (and I do), get a triple. You may look like a hamster on a wheel, but you may have the personal triumph of not walking.

I thought this was more due to how close the top jockey wheel is to the cassette the closer the crisper the change, it then shouldn't matter the length of the cage, as it is the jockey wheel moving in the cage as the cable is adjusted that moves the chain, the close the chain to the cassette the quicker it picks up or drops off.

 

[sreten]

Hi,

FWIW my 52/42 front allows me to use most of the 7 speed 28/14 rear gears most of the time.
The large overlap means I can average out the wear on the rear cluster between rear gears.

If thats not clear, I change the front about every half hour. That is about two rear gears.
Why I do it is the low or high gears available, but it also has the effect of changing
the rear gear typically used by two rear gear wheels, and that evens out the wear
on the rear sprockets of the cluster, i.e. spreading typical rear sprocket wear.

i.e. even on a ~ flat ~ no wind loop I'd still change the front to even out
rear wear. The gearing overlap allows you to do it with no consequnce.

Consequently even if you don't need two front ratios, having them is not bad.

Sticking to the central cog of a front triple nearly all the time works, but wears
out the rear faster than changing the front to use more extreme rear gears,

rgds, sreten.

 

[slowmotion]

I thought this was more due to how close the top jockey wheel is to the cassette the closer the crisper the change, it then shouldn't matter the length of the cage, as it is the jockey wheel moving in the cage as the cable is adjusted that moves the chain, the close the chain to the cassette the quicker it picks up or drops off.

Yes, you are right. Whatever the reason, long cage rear deraillers tend to shift a bit more "wonkily" in my limited experience.

 

[Nigelnaturist]

Thanks. The ratio method makes more sense to me at the moment. I have to think," chainwheel 1 rev , rear cog 2 revs x wheel of 27 = 54 etc. Even then im not experienced enough to relate to the effort involved ,well not immediately lol.

same set up in ratios

and possibly the 9sp

The 1:1 on the 28x27 is due to rounding and tyre size.

 

[talisman50082]

Very interesting, im learning,thanks all.

 

[talisman50082]

same set up in ratios

View attachment 61232

and possibly the 9sp

View attachment 61233

The 1:1 on the 28x27 is due to rounding and tyre size.

Assume you dont use the 28x27 anyway ?

 

[Nigelnaturist]

though with a wider range say upto a 32 on the rear you would get a 34x32 which quickly is 34/32=1.06

if you use a spread sheet its easy to create a table and play about,

 

[talisman50082]

Err forget what i just said lol.

 

[Nigelnaturist]

Me I have a 26x27
This is my current set up with both gear inches and ratios.

Though I am considering this for around here, as I don't generally go much lower than a 42" unless I want to spin up the hills thats when the inner ring comes in useful not when you run out of gears

Compare with a compact double to get the same range. you can also make up your own ratios easily with 9sp cassettes by spliting them so from two cassette the one below and one starting at 12 you could have 12/13/14/16/18/20/23/26/30

 

[talisman50082]

Thanks its becoming clearer

 

[Chris S]

Heard it were a bit flat your way on

It's not Sheffield but it's not the London floodplain either.