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I have had the Crank Bothers 20 tooth chain ring on order since early march with no expected ship date in the near future.

Anyone know of another company that makes a 20 tooth chain ring?
 

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ballbuster
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Check the weight weenies forum...

Flooredsubaru said:
I have had the Crank Bothers 20 tooth chain ring on order since early march with no expected ship date in the near future.

Anyone know of another company that makes a 20 tooth chain ring?
Do a search there. There was a discussion on 20t chainrings. IIRC, Extralite makes one that is sort of a square instead of round, so the chain fits over the crank arms. I think they also said it chainsucks really easily.
 

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The talk about the 20t chainrings had to do with the 4 bolt VS 5-bolt spiders. The problem is that the 5-bolt spiders don't fit over external bearing bottom brackets. My guess is that Race Face and others have gone to the 4-bolt spider so that the chain rings will fit over the external bottom bracket bearings.

Pete
 

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RHRF!
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Action Tec

Flooredsubaru said:
I have had the Crank Bothers 20 tooth chain ring on order since early march with no expected ship date in the near future.

Anyone know of another company that makes a 20 tooth chain ring?
Try Action Tec - http://www.actiontec.us/index.htm

I run a 20t on my RF Deus 4-bolt and it works like a champ!
 

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Dr Gadget is IN
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Boone?

I'm running a Boone 20t/64mm/4bolt ring - with no problems. Around $40 shipped, just had to wait a couple weeks. Vs $71+ S&H and maybe faster service. Hmmmm.

Question: "4 bolt VS 5-bolt spiders" - more detail please? Crankset? Multi-pattern spider? Enquiring minds want to know!

I'm looking at TA Carmina spiders - which fit the Shimano XTR spider spline, and come in just about every BCD. FSA Afterburner crank has Ext BB and removable spider.....
 

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Very cool that people are making 20t chainrings for 4-bolt cranks. Boone and Action tec both make awesome stuff that really lasts.

There was a thread going a while back wondering why Race Face and others went away from the 58mm / 5-bolt standard for their chain rings. Some said that they did it just to be like Shimano, like they were selling out to The Man. I figured that it was something a little deeper than that. The 58mm bcd chainrings just didn't fit around the external bearing BBs... at least the ones that I've got don't.

having a 20t chainring that fits the 64mm bcd 4-bolt standard is awesome and building it out of titanium will allow it to be strong and capable of handling the torque put out by cyclists while getting rid of the excess metal that otherwise would rub against an external BB.

Very, very cool news. I'll order one up.

Pete
 

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Dr Gadget is IN
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Ahhh - now I get it.

4 bolt versus 5 bolt - duh. I figured that was all about lightness - 5 bolt was for big rings, the 94/58-6 was a bit overbuilt, but looked "conventional". 4 bolt is lighter and strong enough - and the BCD's fit the 22/32/44 common set very well. I think the ExBB fit is coincidental, but that certainly sets the lower limit.

It's us folk that want to stretch the range that aren't as well served by this. I've been running a 20t on my 26ers since SunTour days, so a 22t on a 29er did NOT cut it. 20t/29er is acceptable, but I wish I had an 18t to give me back that "resting gear". 18/30/48 :thumbsup:
 

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Check with Boone

I just ordered 20 and 31 tooth 4 bolt rings from Boone the other day. He said the 20 was in stock and the 31 would be done early next week. BTW, they also confirmed that the 20t is slightly squared to eliminate the need to modify the chainring bolts, which would otherwise hit the chain. 20 is definately the lower limit for the 64mm BCD.

Mark
 

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I've been endeavouring to resolve my driveline. My ISIS Turbines finally bit the dust after several seasons of dutiful service. Very had to find new 94mm BCD stuff in ISIS. I'm looking at Middleburns (new, in square taper or ISIS) or used RF Turbine ISIS right now.

Going to run 29x11/34 in a 1x9 or 20/29x11/34 duallie. 1x9 with a 29t front will cover the vast majority of what I ride locally.

Picked up some FSA 29t and Action Tec 20t for compact drive from MC FWIW.
 

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I got the action tec 20t last week. I had to grind the chainring bolt tabs on my Octalink generation XT crank a bit so the chain would seat on the chainring. I like having the 20t on my heavy 26" bike.
 

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I got my 20 and 31 tooth Boone rings last week, and they look sweet! Sorry, I forgot to take pictures before I mounted them. They mounted up no problem to my XT M760 cranks without any modifications. If you look down while riding in the granny, you can see the chain going forward and back because of the squared profile, but I can't feel it. The shifting to the ramped 31 tooth is also pretty good. Hopefully they last as long as they say!

Mark
 

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Always Learning
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Padre said:
I bought two ti 20t 4 bolters from the mountain bike hall of fame a while back.

they run flawlessly with my RF Atlas cranks and Madre's XT's.
Ditto here. I've got one of the Hall of Fame's 20T's on my XT on the Sugar. For others still looking for that granny ring, I wonder if they still have some to sell or are making any more? I wouldn't mind having a spare or two for the future. By then, hopefully the 29"er chainring options will have increased due to the size of the big wheeled bike market growth.

I've got a RaceFace 20T on my Dos Niner (RaceFace Next LP compact 5 bolt crankset). I stocked up with a pair of RaceFace and Salsa Pro 20T's in case they became extinct (both still are still available at Speedgoat).

BB
 

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94mm BCD / 5-arm / "compact drive" are the only consistent solutions to 29t middle rings and 20t grannies (that's right my granny has 20 teef).
 
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