Add a chainring?

[Wayne Potgieter]

Ok, so i recently upgraded from a RC1000 to a RC3000Carbon

 

 

 

It runs Shimano Tiagra components.

 

 

 

It only has the 2 chain rings in front, but i woould like to add a 3rd smaller one.

 

 

 

Can this be done?

 

 

 

If so how?

[TNT1]

you can't add a ring. you need to change the crank to a triple.

[Tumbleweed]

why do you want to do that? hills? maybe consider a compact instead of a triple.

[Wayne Potgieter]

why do you want to do that? hills? maybe consider a compact instead of a triple.

 

 

 

Huh?

[Tumbleweed]

why do you want to do that? hills? maybe consider a compact instead of a triple.

Huh?

 

a normal double crank is usually geared with 53/39. a compact carries 50 34. makes the hills a little easier.

[Wayne Potgieter]

ok, i see.

 

 

 

So according to Raleigh, my original bike had a 52/42/30 tooth combo, but the new one has a 52/39 chainring set.

 

 

 

So in order to get roughly the same range as my original bike i could in theory find a 52/30 combo.

 

 

 

That would give me the same low end and same high end, but obviously not the same midrange options.

 

 

 

Is that about right?

[TNT1]

You wont get a 30t ring to fit a standard (non compact) crank.

[Wayne Potgieter]

so my best bet is then a 50/34?

[TNT1]

on a compact, most probably.

[rock]

either way it a whole new crankset, so just chose weather you wnats a tripple (new front derailleur as well I suspect oh and new shifters) or just get a compact crank.......

 

 

 

or just get a new cassette with a wider range like a 12-27t......

[Tumbleweed]

You wont get a 30t ring to fit a standard (non compact) crank.

 

sorry, typo. should read 36. think the smallest you can get on is a 34?

[Slowbee]

while on this .. how do you work out the gearing ratio's?

 

 

 

[TNT1]

 

 

You wont get a 30t ring to fit a standard (non compact) crank.

 

sorry' date=' typo. should read 36. think the smallest you can get on is a 34?

[/quote']

 

Smallest you can go on a 130mmBCD double crank is a 38t.

TNT12010-01-04 04:53:04

[TNT1]

 

while on this .. how do you work out the gearing ratio's?

 

 

 

 

http://www.sheldonbrown.com/gears/

 

Calculate in gear inches

 

 

 

 

[Johan Bornman]

If your bike is 9-speed you can apply a little trick someone taught me the other day. Buy a Shimano SLX 11-28 cassette. This gives you a nice bail-out gear and the jockey seems to put up with the wide range in spite of the actual spec suggesting that the range is a bit too wide for it.

 

 

To work out if any of these combos are actaully better than what you have or to compare them, simply divide the chainring size by the sprocket size e.g. 52/28=1.86

 

Compare this to a 50 upfront with a 25 at the back  50/25=2.0

 

The smaller number is the easiest gear. No need to work out the actual gear advancement.

 

 

 

Johan Bornman2010-01-04 05:00:56

[rock]

.......shimano also do a 9sp 12-36t cassette now........

 

but thats juts getting a bit ridculous,

 

 

 

I think Johan's idea of the new cassette will be the best, cheapest and easiest option.......