Touring gear ratios- how to change road setup

PV65

Hi, this might seem like a stupid question...I have a Giant Defy 3 that I intend to use for a trip from Northern Spain to Cherbourg. As the tour will involve the Cantabrian Coast & Pyrenees, I was wondering how I could change the gearing to cope with the steep hills. Current setup is 30/39/50 front & 12-25 on the rear. Can I simply change the small front ring or do I need completley new chainrings? I'm in my late 40's and not a great climber so any advantage that I can get would be appreciated. Thanks for any advice, PV65

iantw

The simplest and lowest costoption would be to change your rear cassettee to something like an 11 -32, with the front triple that should help you get up most inclines, -it works for me!

mercia_man

You should be able to change your inner ring cheaply and easily. I assume you have a standard road triple chainset with a 74 BCD size inner ring. That means you can get a TA or Stronglight inner down to 24 teeth from places like Spa Cycles or Wiggle for a little as around £7 for a steel ring or £21 for an alloy ring. All standard road chainsets, as far as I know, use a 74 BCD inner, including Campag and Shimano.

I'm currently using a 24/39/46 set-up on a Campag Veloce chainset on my touring bike with no problems. I previously used a 24/40/48 set-up but didn't need such a high top gear. Keeping your 50 outer ring, I reckon a 26 tooth inner would probably be better although a 24 ring may work OK. From experience, you can push front and rear mechs to cope with much bigger than their stated ranges.

With a 25 biggest rear sprocket and a 26 ring up front, you'd have a 28 inch bottom gear - sufficient if you are not too heavily loaded.

You may find the chain tends to fall off on the change down from middle to inner with such a big drop. A Deda Dog Fang (which I use) or a metal chain catcher attached to the front mech will cure that.

Changing the cassette to an 11-28 or 11-32 is another option, although a bit more pricey. An 11-32 with your existing set-up would give a 25 inch bottom gear.

MichaelW

Most front mechs have a spec for tooth difference from smallest ring to largest. You can exceed it a bit but you sacrifice some slickness in the shift. The lower the mech has to travel, the more inboard it travels so you can expect to shunt the chain onto the BB occasionally. This happened with my Campagnolo Mirage 30/40/50 when i switched to a 24. 26 would probably be the lowest to aim for. Or get a new smaller chainset and lower the front mech.

andrewjoseph

You may need a new rear mech to cope with anything bigger than 28t. I have a medium ultegra rear mech and 32 is the max it can take.

PV65

Mercia Man wrote:

You should be able to change your inner ring cheaply and easily. I assume you have a standard road triple chainset with a 74 BCD size inner ring. That means you can get a TA or Stronglight inner down to 24 teeth from places like Spa Cycles or Wiggle for a little as around £7 for a steel ring or £21 for an alloy ring. All standard road chainsets, as far as I know, use a 74 BCD inner, including Campag and Shimano.

I'm currently using a 24/39/46 set-up on a Campag Veloce chainset on my touring bike with no problems. I previously used a 24/40/48 set-up but didn't need such a high top gear. Keeping your 50 outer ring, I reckon a 26 tooth inner would probably be better although a 24 ring may work OK. From experience, you can push front and rear mechs to cope with much bigger than their stated ranges.

With a 25 biggest rear sprocket and a 26 ring up front, you'd have a 28 inch bottom gear - sufficient if you are not too heavily loaded.

You may find the chain tends to fall off on the change down from middle to inner with such a big drop. A Deda Dog Fang (which I use) or a metal chain catcher attached to the front mech will cure that.

Changing the cassette to an 11-28 or 11-32 is another option, although a bit more pricey. An 11-32 with your existing set-up would give a 25 inch bottom gear.

Thanks for the advice, for the small outlay of around £7- I will try the 24teeth ring solution first and hope that works, if not will then try the 26. I wont be carrying too much, Terra Nova Tent & sleeping bag and few bits and pieces. Will add the chain catcher aswell. Thanks again.

andrew_s

The simple options to reduce the gearing on a road triple are:
a) change the inner ring for a smaller one (down to 24T)
Depending on your front mech, you could find that the cage isn't long enough to keep the chain run above the bottom of the cage. If it's a problem, you could fit a smaller large chainring so you can lower the mech. 48/38/24 certainly works fine - I've been using that for years.
b) fit a bigger cassette
If you go over 30T, you'll probably need an MTB rear mech (9-speed, NOT 10-speed), otherwise the top jockey will rub on the sprocket. The limit depends on the gear hanger length, so it's possible that 32T could work

Mercia Man wrote:

You should be able to change your inner ring cheaply and easily. I assume you have a standard road triple chainset with a 74 BCD size inner ring.

Some of the most recent Shimano road triples mount a 92mm bcd (iirc) inner ring onto the middle ring rather than the cranks. If that's the case, you'd need a 130-74 converter chainring to go lower than 30T