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rider
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2,356 Posts
29t not possible on 104mm BCD. If you can find a 30t in that BCD it won't be round. 31t rings do exist for sure.

For the definitive answer on this subject:
[email protected]

He has taken over production of the Boone Ti chainrings. I'm running a 29t Boone ring on a 94mm BCD 5 arm crank. Shifts great. But I did have to file for chain sideplate clearance on the ends of the 5 arms.
 

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meow?
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175 Posts
Discussion Starter · #4 ·
I'm not apposed to modding my cranks some, but can't you only use the Extralite as a little ring?

heard great things out of the Boone/Brown camp, but I had a buddy trying to get a ring out of them for a couple of months and that was a standard 32t. I wonder if I could get a custom in a decent amount of time?

what I'm trying to do is gear my bike for how out of shape I am. I have a 5" 26" bike that I have been riding for over 2 years and decided to try out a 29r. I'm running it 3x9 w/ 11-34 and don't really ever use the granny on all our local trails. I bought a Karate Monkey and set it up as a 1x9, 32t w/ 11-34. unfortunately I've only ridden it one time and the gearing was just to big for my conditioning, I think a 30t would be perfect though. I made it up all the climbs, but it just wiped me out.

most people seem to say a 20t/30t combo would be perfect, just thought there might be some options I wasn't aware of.

JW
 

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try driving your car less
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3,097 Posts
might be cheaper/easier to get a square taper 5 bolt 94 mm BCD crank and a 30t ring. those rings are readily available. the BBs are cheap and easy to get. then got to ebay or whatever for some raceface cranks or some such thing. just an option to throw out there.

The other option for your existing cranks is to just put on a 'big' granny ring and ride that.

IwantCake said:
I'm not apposed to modding my cranks some, but can't you only use the Extralite as a little ring?

heard great things out of the Boone/Brown camp, but I had a buddy trying to get a ring out of them for a couple of months and that was a standard 32t. I wonder if I could get a custom in a decent amount of time?

what I'm trying to do is gear my bike for how out of shape I am. I have a 5" 26" bike that I have been riding for over 2 years and decided to try out a 29r. I'm running it 3x9 w/ 11-34 and don't really ever use the granny on all our local trails. I bought a Karate Monkey and set it up as a 1x9, 32t w/ 11-34. unfortunately I've only ridden it one time and the gearing was just to big for my conditioning, I think a 30t would be perfect though. I made it up all the climbs, but it just wiped me out.

most people seem to say a 20t/30t combo would be perfect, just thought there might be some options I wasn't aware of.

JW
 

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rider
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2,356 Posts
Another option, since you don't use your current granny, would be an old school 110mm x74mm BCD crankset. Say 28t on the 74mm BCD (24-30t are available), 34-36t on the middle and bashring or 40-44t on the outer. Options are good.
 

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IwantCake said:
I'm not apposed to modding my cranks some, but can't you only use the Extralite as a little ring?

heard great things out of the Boone/Brown camp, but I had a buddy trying to get a ring out of them for a couple of months and that was a standard 32t. I wonder if I could get a custom in a decent amount of time?

what I'm trying to do is gear my bike for how out of shape I am. I have a 5" 26" bike that I have been riding for over 2 years and decided to try out a 29r. I'm running it 3x9 w/ 11-34 and don't really ever use the granny on all our local trails. I bought a Karate Monkey and set it up as a 1x9, 32t w/ 11-34. unfortunately I've only ridden it one time and the gearing was just to big for my conditioning, I think a 30t would be perfect though. I made it up all the climbs, but it just wiped me out.

most people seem to say a 20t/30t combo would be perfect, just thought there might be some options I wasn't aware of.

JW
The smallest ring Boone makes for 104mm is a 31t. I have one, and even with that I had to take a dremel to my crank spider to keep the chain from hitting it. The Extralite 30t is designed to be run 2x9 (middle and big ring, no granny), so it has no shift ramps or profiled teeth. It should work fine on a 1x9 setup. It will probably be okay with a granny too, it just won't shift as some people might like. Boone also makes 64mm rings in 20t and 21t. The really long wait for Boone rings was the case a year or more ago when he had a full time job on top of making the rings. Now he's just making the rings, and I think the wait times are weeks, not months.
 

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No longer 26
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3,090 Posts
Yeah, If you are not using your granny but need something a bit less than 32, maybe go 24 or 26 small x 34 or 36 middle. I am running 22/36 on my Supercal29 and it fits the bill for me great. This is on a standard 4 bolt Bontrager Race GXP crankset. Race face makes rings these sizes. Probably others too. Got mine at speedgoat.
Greg
 

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NMBP
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2,159 Posts
VT Mike said:
The smallest ring Boone makes for 104mm is a 31t. I have one, and even with that I had to take a dremel to my crank spider to keep the chain from hitting it.
I have a Boone 31 tooth on my XT Hollowtech and didn't have to modify the spider. It shifts fine. I did have to modify the crank to get my 20 tooth granny to work.
 

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Another possibility is to go for a Middleburn crank with the Duo spider/ring, thats a 29t. The spiders are removable so you could go four or five arm if you wanted in the future.
 

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i 2nd the 5 arm (58/94) compact

jh_on_the_cape said:
might be cheaper/easier to get a square taper 5 bolt 94 mm BCD crank and a 30t ring. those rings are readily available. the BBs are cheap and easy to get. then got to ebay or whatever for some raceface cranks or some such thing. just an option to throw out there.

The other option for your existing cranks is to just put on a 'big' granny ring and ride that.
Their also avaliable in ISIS. But they offer the most versatility in gearing...
 

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highly visible
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3,284 Posts
Third for the 5 arm 58/94mm

That really is going to be the easiest way to do 29t or 30t with a 20t granny. Those cranks were widely available in the mid to late 90s. Nicer ones (Ritchey, XT-M737?) come up occasionally on eBay, and if you're willing to put up with 50-100g more weight you can get basic Suntour and Shimano ones pretty easily. I've got a decent looking Suntour 58/94crankset sitting on my wife's 1999 MTB just waiting for me to swipe if I decide I need to go 20/30/40.
 

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rider
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2,356 Posts
AuntieAPE said:
chainreaction in the UK has raceface 94/58 CD cranks available for a good price, even after international shipping. who knows how many are left though.
Thanks, just scored a pair of square taper RF North Shore in 94/58mm BCD. Shipped for $101!
 

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Can I get a 30 21 setup for my XTR's?

I was checking the Boone Chainring website and it looks like I can order a 31T 102 mm middle and a 20T 64mm inner for the XTR 760's.

Am I reading this right? I was going to use a brand new set of XT's (42,32, 22) on my 29er build.

If I this works out I would be willing to swap my XTR 760's from my 26er and just get rid of my outer ring. What do you guys think?
 

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Always Learning
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9,608 Posts
IwantCake said:
I'm not apposed to modding my cranks some, but can't you only use the Extralite as a little ring?

heard great things out of the Boone/Brown camp, but I had a buddy trying to get a ring out of them for a couple of months and that was a standard 32t. I wonder if I could get a custom in a decent amount of time?

what I'm trying to do is gear my bike for how out of shape I am. I have a 5" 26" bike that I have been riding for over 2 years and decided to try out a 29r. I'm running it 3x9 w/ 11-34 and don't really ever use the granny on all our local trails. I bought a Karate Monkey and set it up as a 1x9, 32t w/ 11-34. unfortunately I've only ridden it one time and the gearing was just to big for my conditioning, I think a 30t would be perfect though. I made it up all the climbs, but it just wiped me out.

most people seem to say a 20t/30t combo would be perfect, just thought there might be some options I wasn't aware of.

JW
Now where's Nat to come along and say "get your backside in shape"! :D

Looks like the best options are to....

1. Add a granny ring, front derailleur and shifter.
2. Get a different crank that allows a smaller ring if you want to stay 1x9.
 

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palmermtb said:
I was checking the Boone Chainring website and it looks like I can order a 31T 102 mm middle and a 20T 64mm inner for the XTR 760's.

Am I reading this right? I was going to use a brand new set of XT's (42,32, 22) on my 29er build.

If I this works out I would be willing to swap my XTR 760's from my 26er and just get rid of my outer ring. What do you guys think?
Quite honestly I would just run a 22/32 if your taking that route which would be lots cheaper, give you decent range and prolly be adequate after a month or so of gettin your legs in shape for that gearing. I run a 20/29 Boones with a raceface 42 and I rarely use the 20 anymore. Im seriously considering going to a single 29T and save the hassle of dropping chains etc. that comes with running a 20T. I found that the sram 3 front deraileur; designed for 42T max seems to do a better job for shifting than a 44T max der. but they dont last long.
 

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Always Learning
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9,608 Posts
Fisty said:
Quite honestly I would just run a 22/32 if your taking that route which would be lots cheaper, give you decent range and prolly be adequate after a month or so of gettin your legs in shape for that gearing. I run a 20/29 Boones with a raceface 42 and I rarely use the 20 anymore. Im seriously considering going to a single 29T and save the hassle of dropping chains etc. that comes with running a 20T. I found that the sram 3 front deraileur; designed for 42T max seems to do a better job for shifting than a 44T max der. but they dont last long.
Of course, if IWantCake does go to a front derailleur on the Karate Monkey, he is going to have to deal with the KM clearance issues. So I might as well provide the Surly Blog link dealing with all of that:

http://www.surlybikes.com/spew12.html

BB
 
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