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Old 12-25-10, 09:18 PM   #1
rufus
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Gunnar Rockhound 29er frame, and then Bikesdirect for a parts loaner?

I'm kinda having the jones for a nice steel 29er hardtail, and have pretty much decided on the Gunnar Rockhound. Possibly a Niner MCR, but I like the idea of an American made steel frame.

So I'm looking at this

and figure I can pick this up from Bikesdirect to use for parts for the time being.

What problems might I run into doing this? From what I can see so far, I'll probably need a new front derailleur, or at least a new clamp to fit the smaller diameter steel frame. Also a new BB for the 73mm shell. Then just upgrade/swap out parts over time as I have the money, starting with fork and wheelset.

But everything else should swap over just fine, right?
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Old 12-26-10, 02:39 AM   #2
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Do it! Only issues I see: new derailleur. Maybe there's a shim out there for the derailleur clamp? Seatpost diameter are the same and you can use the same BB. The difference between BB shells are simply spacers. So either add or subtract based on the BB shell width.
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Old 12-26-10, 05:34 PM   #3
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Originally Posted by commo_soulja View Post
Do it! Only issues I see: new derailleur. Maybe there's a shim out there for the derailleur clamp? Seatpost diameter are the same and you can use the same BB. The difference between BB shells are simply spacers. So either add or subtract based on the BB shell width.
Looking at this link from Sram,

http://www.sram.com/_media/techdocs/...0Cranksets.pdf

it appears I wouldn't need a new bottom bracket as you say. It looks as if the Truvativ crank and BB are set up to achieve the correct chain line with a 73mm bottom bracket. For a 68mm BB, you need to install two 2.5mm spacers to achieve the same chain line. So if I'm reading this right, the two spacers will be installed on the BB used in the Motobecane, and all I'd need to do is remove them to fit the BB into the 73mm BB of the Gunnar.
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Old 12-27-10, 04:46 AM   #4
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Originally Posted by rufus View Post
Looking at this link from Sram,

http://www.sram.com/_media/techdocs/...0Cranksets.pdf

it appears I wouldn't need a new bottom bracket as you say. It looks as if the Truvativ crank and BB are set up to achieve the correct chain line with a 73mm bottom bracket. For a 68mm BB, you need to install two 2.5mm spacers to achieve the same chain line. So if I'm reading this right, the two spacers will be installed on the BB used in the Motobecane, and all I'd need to do is remove them to fit the BB into the 73mm BB of the Gunnar.
uhh... did you read my post:
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Originally Posted by commo_soulja View Post
Do it! Only issues I see: new derailleur. Maybe there's a shim out there for the derailleur clamp? Seatpost diameter are the same and you can use the same BB. The difference between BB shells are simply spacers. So either add or subtract based on the BB shell width.
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Old 12-27-10, 04:46 PM   #5
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Yeah, but I was a bit confuzzled, as this would be my first encounter with external bottom brackets. I wasn't sure just what you meant by spacers, and how they were used. Never realized they were part of the design of the whole external BB itself.

In any event, as much as it pains me, as hard as it is for me to resist, I've decided to hold off. It's a matter of want versus need, and as much as I might want a nice steel hardtail 29'er, I don't really need one. What I need is to pay off some credit cards, and ride my RM Blizzard a lot more.

Now whether I can actually live by this decision, I don't know.
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