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  1. #1
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    Quick question

    fellow SS riders, I have a question about chainring replacement. Forgive me for my ignorance and please don't say use the search function because I have. I recently bought a beater Trek 3700 aluminum frame 26". I come from a bmx background and decided to take this on as a budget project. I stripped the frame to bare aluminum, swapped the rear wheel to cassette style hub and installed a Forte single speed Kit. Now I want to get rid of the 3 speed chainring in the front with a single one. Can some one explain to me in simple terms how to do this? The current ones are riveted together. I want to replace all 3 with a single one. I don't want to take the big ring and little ring off, I want to replace the whole unit

  2. #2
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    you didn't search very hard.

    you either need to remove the current chainrings and replace them with a single ring, or you need a new crankset and maybe a bottom bracket. you will also need special tools. try LBS for a used parts if you are trying to keep the budget down. there is a lot of compatibility issues, too many to try and explain in simple terms. you could maybe score used parts for $20-30.
    Rigid SS 29er
    SS 29+
    Fat Lefty
    SS cyclocross
    Full Sus 29er (Yuck)

    Stop asking how much it weighs and just go ride it.

  3. #3
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    I did search. I just don't understand the terminology or know enough about mtb lingo I guess. I just want to make sure my chainline is true. I asked my lbs they said for 1500 you can buy this bike over here. I can buy a craNk puller no big deal. My confusion was can I just buy a ss chainring pop it on and go. That's what I did with my 20"s. Back to the World Wide Web I go.

  4. #4
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    Cheap crankset with removable rings and either a single speed or narrow/wide chainring

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    delete
    Last edited by *OneSpeed*; 05-23-2015 at 06:55 PM.
    Rigid SS 29er
    SS 29+
    Fat Lefty
    SS cyclocross
    Full Sus 29er (Yuck)

    Stop asking how much it weighs and just go ride it.

  6. #6
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    Watch a youtube video on chainring replacement. See how the rings are bolted on. I'll bet your crankset doesn't have chainring bolts, the cheap riveted ones typically expect you to swap out the entire crankset.

    See if you can see how the cranks are attached. If there's a square hole in the cranks that fits onto a square fitting on the bottom bracket (google it up: square taper bottom bracket), it gets a tad more complicated, because there just aren't that many cranks out there that accept the sort of chainrings everybody is using (the ones with four holes).

    If the cranks are prominently marked "SR Suntour," the rings aren't replaceable and you have a square taper bottom bracket.

    Check out the shimano acera crankset, I think that might work, you can find them for about 30 bucks on the internet. You would buy a crankset that has three rings, take the rings off. Then you get some single stack chainring bolts and use those to bolt on your new chainring. (For now, you can probably get away with using the middle ring, just put it back on there with the new bolts.)

    Then, assuming your bottom bracket is OK, just cram em on there. In fact, run out to the garage right now and turn the cranks. If it's nice and smooth, good. If they feel notchy, you'll need a new bottom bracket. The less expensive bottom brackets are designed to be easy to swap out, although I agree that might be one area where if they don't come out easily (with the right tools!) you can get the bike shop to bail you out.

    Getting them off and on isn't hard, watch youtube and buy the tools, you'll need a crank puller, some hex wrenches, a pedal wrench and a chainring bolt tool. Just note that the crank puller for square taper is different from a spindle type bb (google up octalink bb and you'll see what I'm talking about.) The cheap cranks are usually square taper though.

    I support you in trying to figure this out yourself. If it won't break your heart if things don't go well, dive on in. This is how you figure out how to work on stuff. The bike shop idea is fine if it really positively has to be done right. If you're just messin around in the garage, go for it.

    Run down to Harbor Freight and get a set of metric ball-end hex wrenches, get the big ones not the little tiny ones. And a crescent wrench. Pick up a set of plastic calipers while you're down there. Report back.

  7. #7
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    Thank you for Dave for the response. I have all the tools needed except a crank puller and bb socket as I am a car junkie. I do have a 73x122.5 square taper bb. I'm probably going to replace it with a un55 bb just because I can get it for 20bucks. Thank for the advice on the chainring. I wish I could have a thick anodized ss chainring but it looks like I am stuck with tearing apart a 3ring and using bolts right? What is the difference between my bottom bracket and the ones on these other ss bikes I see on here that look so nice.

  8. #8
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    Nah you can use a pretty chainring, the old rings come off and the new one goes on. "104 BCD" four hole is pretty standard. Check out Endless Bike, gorgeous stuff there. Really cool chick runs that company.

    You can buy cranks without the rings, although weirdly sometimes it's less expensive to buy them with the rings. Even the ones you see on ebay that come with a single ring, with the right bolts they will take two three rings.

    You can get direct mount chainrings (without bolts). But not in my price range.

    A lot of people are using external bearing bottom brackets. So you move the bearings out of the cartridge, into a ring that sits on either side of the shell, frees up room in there so you can run a big axle. Check out the Shimano Hollowtech stuff. Also Raceface has some nice cranks, a lot of people here like the Turbines. The raceface exi bottom bracket is basically the same as the Shimano. Basically boils down to what you want to spend, you can pick up some shimano XT or raceface ride cranks for ~130 including the ring and bottom bracket. If you're diligent you can get good deals on take-offs and lightly used parts. Course like anything in cycling, the sky's the limit.

    I've been swapping a couple of Shimano and Raceface cranks between three bikes I've been monkeying with, four rigs in total. (I have everybody in the family trying out 1x in different crank arm lengths.) For a given arm length, if I close my eyes I can't tell the difference from one crankset to another.

    If you think you'll really like building bikes, it's ok to invest in a set of cranks you like, if you figure you'll pull them and use them on your next project. It won't increase the value of your bike, so don't plan on getting your money back if you sell it.

    Anyhow, get a feel for what you want to do crank-wise before you buy the new bottom bracket, there's all kinds of stuff you can screw into that shell if you want.

    Speaking of crank pullers, Park Tools cwp7 will pull either square taper or spindle cranks, and is a good investment if you think you might be doing this a lot. If you go out and buy shimano cranks, there's a special tool you'll need for that also.
    Last edited by TampaDave; 05-24-2015 at 04:03 AM.

  9. #9
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    Quote Originally Posted by BENKD29 View Post
    you didn't search very hard.
    actually i don't think you read very hard. he said his three rings are riveted together. that usually means they can't be replaced and are on a crankset that is probably not worth saving anyhow.

    without seeing a picture of the cranks to confirm it; i'd guess you'll need new crank arms. at that point just buy singlespeed cranks and you'll get the ring included.

    lots of old cranksets could also be converted; just look for any that have removable chainrings. remove the old rings and add singlespeed ring or just start with the middle chainring until you wear it out. you'lll need shorter singlespeed/track crank bolts.

  10. #10
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    Thanks Max, what you are saying seems to make sense. I currently have it on the middle ring ,36-16 is my gear ratio. Seems to be working well enough although I can run out of gear on flat pretty easily. I think I'm going to keep this as a beater bike and start researching new SS bikes.

  11. #11
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    Yeah kind of hard to beat a frame set up for ss.

    Two suggestions for bikes that can swing either way.

    Surly bikes are like transformers, you can turn them into anything. Some have elaborate multipurpose cut outs and others have swappable chips.

    Also check out the niner SIR with that gorgeous carbon fork. Eccentric bottom bracket, which is the other way to tension a chain.

    I'm on a trek ss, one of the least expensive ways to get a highly decent ss although it's not a transformer. Man needs more than one bike anyways.

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