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 Post subject: Smallest ring 74bcd?
PostPosted: Thu Jun 27, 2013 11:31 am 
Gold Trader
Gold Trader

Joined: Wed Feb 04, 2009 9:40 pm
Posts: 2157
Location: Nottingham
Am I right in assuming that smallest inner ring (without complication of adaptors) for M730 XT cranks is 24T?

Thanks.


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 Post subject: Re: Smallest ring 74bcd?
PostPosted: Thu Jun 27, 2013 11:51 am 
Old School Grand Master

Joined: Tue Oct 09, 2007 1:55 pm
Posts: 8202
Location: New Forest, UK
Yes. Any smaller and the bolts would be outside the teeth!

No doubt some wise guy will be along any minute to say that some rogue CNC shop in the USA once made a 23T...


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 Post subject: Re: Smallest ring 74bcd?
PostPosted: Thu Jun 27, 2013 12:10 pm 
Gold Trader
Gold Trader

Joined: Wed Feb 04, 2009 9:40 pm
Posts: 2157
Location: Nottingham
No doubt!

Thanks for confirming. Guess I'll have to change the crankset if/when really LOW gearing becomes essential.


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 Post subject: Re: Smallest ring 74bcd?
PostPosted: Thu Jun 27, 2013 12:44 pm 
Gold Trader
Gold Trader
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Joined: Thu Oct 01, 2009 12:31 pm
Posts: 1281
Location: Munich, Germany
I'm faaar from being that wise guy hamster is talking about :) but what you need is an Avid Microadaptor-2.
That way you are able to run a 22T ring.
Check out the bikepro link: http://www.bikepro.com/products/cranks/ ... bolts.html
And if you are really want one convince me to sell mine. ;-)


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 Post subject: Re: Smallest ring 74bcd?
PostPosted: Thu Jun 27, 2013 1:13 pm 
Old School Grand Master

Joined: Tue Oct 09, 2007 1:55 pm
Posts: 8202
Location: New Forest, UK
With the cassettes now on 34 or even 36T I doubt if you'll miss having a 22 - unless you have a cycle rickshaw.

On the tandem I run a 12-32 SRAM 7s cassette with a 24T chainring, which is the same as a 29T with a 22T ring.


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 Post subject: Re: Smallest ring 74bcd?
PostPosted: Thu Jun 27, 2013 1:28 pm 
Gold Trader
Gold Trader

Joined: Wed Feb 04, 2009 9:40 pm
Posts: 2157
Location: Nottingham
Thanks! Surely cheaper to buy a new chainset (and sell the XT) than getting an "Avid Microadaptor-2" (especially if not in UK) and a new ring!

The reason? My COPD (shot lungs) is such that I can only get up the unavoidable hill home on about a 20" gear. Simply trying to put off the day (by maybe 6 months) when only way I can cycle at all is a Brompton so that I can get the bus the last couple of miles back each day. And even then I'll have to add an inner ring and use manual shifting.

Ah the joys of old age...


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 Post subject: Re: Smallest ring 74bcd?
PostPosted: Fri Jun 28, 2013 8:24 am 
retrobike rider
retrobike rider
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Joined: Fri Aug 08, 2008 2:36 pm
Posts: 16746
Location: Yorkshire, England
Hamster, we had 34 rear BiTD before Suntour started the trend for 20 tooth front cogs.

But only wimps* had a 24/34 setup and a good old 24/28 with the lesser weightweenie conscious going for 24/32 ;-). Of course standard was normally a 26 at the front.
Odd how thing come back with 24 now being the standard granny ring at the front on Shimano's chainsets.


*or them wanting extra fun in granny spinning contests. It was not a standard cassette setup though.


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 Post subject: Re: Smallest ring 74bcd?
PostPosted: Fri Jun 28, 2013 8:32 am 
Retro Guru
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Joined: Sat Apr 02, 2011 11:16 am
Posts: 799
Location: Camden, London
wasn't that part of the attraction of "compact" chainsets, they seem to be 42-32-22 as almost standard but used with smaller cogs on cassette [cynic mode] to increase chainwear [end cynic mode]


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 Post subject: Re: Smallest ring 74bcd?
PostPosted: Fri Jun 28, 2013 9:10 am 
retrobike rider
retrobike rider
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Joined: Fri Aug 08, 2008 2:36 pm
Posts: 16746
Location: Yorkshire, England
For Suntour it was :) They shrank the lot, as well as the rear cogs (11-24 rear). Weight, all about weight.
Suntour needed the money as well ;)
But keep the same ratios overall.

Shimano figured, that was a great idea and followed suit, even giving us aluminium small rings just to make sure...


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 Post subject: Re: Smallest ring 74bcd?
PostPosted: Fri Jun 28, 2013 3:37 pm 
Gold Trader
Gold Trader
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Joined: Thu Oct 01, 2009 12:31 pm
Posts: 1281
Location: Munich, Germany
oldave wrote:
Thanks! Surely cheaper to buy a new chainset (and sell the XT) than getting an "Avid Microadaptor-2" (especially if not in UK) and a new ring!


That completely depends on the chainset. ;) By the way i also have a 20T brand new Suntour chainring to go with the Microadaptor. 8)


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