Changing 30 inner ring to a 24?

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cyclingfury
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Changing 30 inner ring to a 24?

Postby cyclingfury » Fri Oct 26, 2012 16:34 pm

Hi,

I currently run a 50-40-30 Campag Chorus Triple (circa 2006) with a 13-29 cassette and long cage rear mech.
My mates and I are planning a ride in the Dolomites next year and for health reasons I would like the security of having a couple of ultra low gears at my disposal.

Would there be any mechanical/compatability issues if I replaced the 30 with a 24 inner ring?
I know that normally a difference between rings should be kept to around 14 which would give me a 26 inner ring, but I've read on other sites that some have stretched this to a 24 with Shimano set ups.

I'm also aware that shifting from a 40 to a 24 may not be quite as slick, but I'm prepared to live with that.

Thanks.
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smidsy
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Re: Changing 30 inner ring to a 24?

Postby smidsy » Fri Oct 26, 2012 17:00 pm

If you can't get up with as 30/29 it's not worth doing is it?
Yellow is the new Black.

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cyclingfury
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Re: Changing 30 inner ring to a 24?

Postby cyclingfury » Fri Oct 26, 2012 17:29 pm

cyclingfury wrote:Hi,

I currently run a 50-40-30 Campag Chorus Triple (circa 2006) with a 13-29 cassette and long cage rear mech.
My mates and I are planning a ride in the Dolomites next year and for health reasons I would like the security of having a couple of ultra low gears at my disposal. Would there be any mechanical/compatability issues if I replaced the 30 with a 24 inner ring?
I know that normally a difference between rings should be kept to around 14 which would give me a 26 inner ring, but I've read on other sites that some have stretched this to a 24 with Shimano set ups.

I'm also aware that shifting from a 40 to a 24 may not be quite as slick, but I'm prepared to live with that.

Thanks.

Given my circumstances, yes Smidsy, it is....
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islandman
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Re: Changing 30 inner ring to a 24?

Postby islandman » Fri Oct 26, 2012 17:45 pm

You tell him mate, are you sure the bcd will be the same for a smaller ring ? Only other thing is will your rear mech handle the extra chain ? Test by holding crank still and pulling more chain onto the crank teeth. If your dropping 6 teeth on inner ring pull 6 extra links onto crank from bottom chain run. Do this while in lowest inner ring and biggest rear cog. Might need a mountain bike rear mech, is this an option with Campy ?
Good luck.

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CPeachey
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Re: Changing 30 inner ring to a 24?

Postby CPeachey » Fri Oct 26, 2012 17:46 pm

It does work. I have 20 and 24t rings on my solos and tandems. If you select small ring to small cog the rear changer won't take up all the slack chain but in practice you only use the small ring with the largest 2/3 cogs. Changing down is not a problem. You throw the chain onto the ring. Changing up needs to be sympathetic. Ease of the pedals while you do it. 30t down to 24t lowers bottom gear from 29" to 23". This will be quite noticeable and is more realistic for long climbs.
PS...on the tandems I use a 20t ring and 34t cog giving bottom gear of 16.5". It saves pushing the loaded tandem up several miles of climb!
Chris

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cyclingfury
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Re: Changing 30 inner ring to a 24?

Postby cyclingfury » Fri Oct 26, 2012 18:26 pm

Thanks for your replies guys. Islandman, I'll try that test for the rear mech - a great idea.
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islandman
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Re: Changing 30 inner ring to a 24?

Postby islandman » Fri Oct 26, 2012 19:47 pm

Yep, good idea except I've got it the wrong way round, thats how to find out how short a chain can be. Quick links come in handy now so you can break the chain and " extend " the chain by hanging it on the appropriate tooth on the crank leaving the 6 link gap to find out if the mech can handle the extra. Sorry about that but there's two ideas that may come in useful some time. Sorry good luck.

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Monty Dog
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Re: Changing 30 inner ring to a 24?

Postby Monty Dog » Fri Oct 26, 2012 20:23 pm

You won't be able to fit a 24t inner on a road triple chainset because normally 30t is the smallest size. To fit a smaller inner rings, you'll need to go for a different chainset with a 74BCD which can take an inner ring down to 24t.With a 24t inner ring, you'll be limited to a large chainring size of 46 tooth because front triple mechs normally have a capacity of 22 teeth.
Make mine an Italian, with Campagnolo on the side..

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CPeachey
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Re: Changing 30 inner ring to a 24?

Postby CPeachey » Fri Oct 26, 2012 21:07 pm

All my triple front mechs cope with a 26t difference. See above post
Chris

Mercia Man
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Re: Changing 30 inner ring to a 24?

Postby Mercia Man » Sun Oct 28, 2012 16:20 pm

I run a Veloce triple circa 2006 (virtually identical to yours) with a long cage rear mech on my touring bike which I use regularly for camping trips in Alps etc. Cassette is a nine speed 13-28. The inner ring is 74 BCD which means it will take down to a 24-tooth ring (widely available). That's what I use - TA do nice alloy ones that look appropriate with the Campag rings. I've never tried this with a 50-tooth outer but I have used it successfully with 48-40-24 and currently run it with 46-39-24. I can use the 24 ring with the five biggest cogs on rear before the chain goes too slack. The mechs cope fine with the difference despite being well over the claimed capacity.

The disadvantages are you need to double shift when going from middle ring to smallest ring and vice versa, while the chain can drop off when you shift from middle to smallest - I've cured that with a Deda Dog Fang. A 39 or 40 middle ring is a nice size for general riding - you can use all the cassette cogs with it so you don't use the front shift so much.


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