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BIG chainrings
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Yanto View Drop Down
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Joined: 11 July 2005
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    Posted: 21 November 2013 at 2:50pm
Hi, I'm after a chain ring, 130 bcd 5 arm, 75 or 80t.

Cheers

Ian
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BarneyH View Drop Down
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Points: 439 		Post Options Post Options   Thanks (0) Thanks(0)   Quote BarneyH Quote  Post ReplyReply Direct Link To This Post Posted: 21 November 2013 at 7:19pm
Ian
 
Raptobike.com component shop and I think their standard as 130mm.
 
Good luck
 
Barney
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Yanto View Drop Down
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Points: 1521 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Yanto Quote  Post ReplyReply Direct Link To This Post Posted: 21 November 2013 at 7:55pm
Cheers Barney, i'll have a look.
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Andrew S View Drop Down
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Points: 2433 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Andrew S Quote  Post ReplyReply Direct Link To This Post Posted: 22 November 2013 at 12:13pm
Try Alligt in the Netherlands - they do beautiful CNC chainrings up to 80T in 110 and 130mm BCD. They also do chainrings with built-in guards which are great for compliance with BHPC racing rules.
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blogwat View Drop Down
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Points: 661 		Post Options Post Options   Thanks (0) Thanks(0)   Quote blogwat Quote  Post ReplyReply Direct Link To This Post Posted: 22 November 2013 at 3:17pm
Hi Ian
I've got a seventy tooth if thats any good for you its 130 bcd shimano type
Jeff.
when your up to your waist in aligators they forget to tell you you've got to clear the swamp
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Yanto View Drop Down
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Points: 1521 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Yanto Quote  Post ReplyReply Direct Link To This Post Posted: 22 November 2013 at 4:53pm
Andrew, Alligt had been mentioned to me, they seem to supply Europe with big rings. Them and Dutch Bike bits are the same price, Raptobite sell them with a small increase in price!

Thanks for the offer Jeff, I'll do some calculations (or rather Sheldon Brown will) and PM you.
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BarneyH View Drop Down
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Points: 439 		Post Options Post Options   Thanks (0) Thanks(0)   Quote BarneyH Quote  Post ReplyReply Direct Link To This Post Posted: 22 November 2013 at 6:18pm
Ian
 
If trying to do gear calcs have you tried k gear from the kinetics site, I find it the most user friendly, its free and seems very reliable for all manner of odd set ups..
 
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Yanto View Drop Down
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Points: 1521 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Yanto Quote  Post ReplyReply Direct Link To This Post Posted: 22 November 2013 at 7:42pm
Easy to use Barney, but I don't understand gear inches or metres, or rather I can't translate them into speed. Mph/100rpm I can understand and "feel".
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BarneyH View Drop Down
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Points: 439 		Post Options Post Options   Thanks (0) Thanks(0)   Quote BarneyH Quote  Post ReplyReply Direct Link To This Post Posted: 24 November 2013 at 10:23am
Ian
 
I don't really understand what the numbers mean on the road either but what I do is to enter the current ratios I've got on whichever bikes I like and then enter the proposed set up to see how my current ratios compare to the proposed, its just a way of comparing to each other - I'm probably doing this all wrong but who cares, I just get out and ride whenever I can.
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Andrew S View Drop Down
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Points: 2433 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Andrew S Quote  Post ReplyReply Direct Link To This Post Posted: 25 November 2013 at 11:42am
Originally posted by Yanto Yanto wrote:

Easy to use Barney, but I don't understand gear inches or metres, or rather I can't translate them into speed. Mph/100rpm I can understand and "feel".
This is essentially Sheldon Brown's "gain ratio" which takes the entire gearing system, including crank length, into account. It relates distance travelled by the pedal to distance travelled along the road, which is the same as your mph/100rpm, only with both sides of the ratio divided by time. Sheldon Brown was a very bright chap.

Personally I find the European system of metres of development (distance travelled per pedal turn) a whole lot more understandable than 'gear inches', the imaginary diameter of some enormous penny-farthing wheel.


Edited by Andrew S - 25 November 2013 at 11:46am
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