quick gear question

[gillelive]

another gears question had a little play on the new sirrus yesterday, mainly to get used to using spds/cleats and to get used to the gears can someone tell me what range I should be using (1-9) when in each of the following chain rings, I had a bit of trouble getting back up to the middle ring when in a granny gear - the bike has the follwing rings 48 x 36 x 26T and cassette: Shimano Alivio, 9-speed, 11-32

Big - ?

Middle - ?

Small - ?

 

[killiekosmos]

Normal advice is to avoid extremes of biggest chainring with biggest on cassette and vice-versa.

If you draw up a table (in Excel) for chainrings and cassette you will see that there is a lot of overlap/duplication and therefore little need to use all combinations.

If I'm in the lowest possible gear (smallest chainring, biggest cassette) then I usually change up a bit on cassette before goint to middle chainring.

 

[2Loose]

The late Sheldon Brown's website has an easy to use gear calculator here
Select wheel size, put in the 48 36 28 values in the Chainrings row, choose 'Gear Inches' in the Gear Units row, then find an equivalent cassette in the associated drop down list.

Then hit the Calculate button. You will be able to see which gears on the middle chainring have similar values to some in the small ring etc. and also how many inches a complete pedal revolution will propel you in each ratio.

 

[Shrim]

Normal advice is to avoid extremes of biggest chainring with biggest on cassette and vice-versa.

Good advice this as I have a Sirrus and notice when using the extremes you can hear the difference and actually feel the difference. I generally try to make sure that the chain, dependant upon which chainring it is on has the straightest possible line to the cassette as I think that using the extremes for a long period can only wear the chain and gears.

 

[Paulus]

Good advice this as I have a Sirrus and notice when using the extremes you can hear the difference and actually feel the difference. I generally try to make sure that the chain, dependant upon which chainring it is on has the straightest possible line to the cassette as I think that using the extremes for a long period can only wear the chain and gears.

Correct. Chains are really designed to run in straight lines. Which is why single speed bikes, and those with hub gears last for many years. Using the extemes, ie large chainring and largest sprocket, smallest(granny ring) and smallest sprocket for extended periods will wear the chain, chainrings and sprockets really quickly.

 

[2Loose]

I completely missed the point didn't I

 

[PpPete]

I completely missed the point didn't I

I don't think so....

Another way the OP might care to look at it is this:
Of the 9 sprockets on the cassette only 7 are available in each chain ring, thus:
Middle chainring - dont use smallest and largest sprockets.
Little chainring - dont use 2 smallest sprockets
Big chainring - dont use 2 largest sprockets

 

[I like Skol]

I don't think so....

Another way the OP might care to look at it is this:
Of the 9 sprockets on the cassette only 7 are available in each chain ring, thus:
Middle chainring - dont use smallest and largest sprockets.
Little chainring - dont use 2 smallest sprockets
Big chainring - dont use 2 largest sprockets

Similar to my method but not quite....

Middle chain ring I use the full cassette.

Little/granny ring only use the biggest 3 sprockets of the cassete because I have done the sums and swapping to the middle ring/biggest sprocket is the same at this point.

Big Chain ring gets used with small half of cassette. So 4 or 5 of the small cassette sprockets.

 

[gillelive]

thanks again, more useful advice as always, i think i am clear now - next time out i will play around and see how it feels