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  1. #1
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    New question here. GT backwoods SS project

    I picked up this 98 GT Backwoods that I want to turn into a daily SS commuter. I have a couple crank compatibility questions, if someone could chime in their knowledge.

    Is this crank compatible with Single speed cranks?




    Large chain ring removed, middle(32t) and granny chain ring riveted together. (minor disappointment) Suntour XR 300

    Re-moveable 42t chain ring shown here.


    2) Am I going to run into problems attempting to fit a aftermarket chain ring?

    3) I feel more capable than a 32t chain ring, what would you recommend as a step up, 36t or 38t? What are my options besides homebrew and surley?

    4) What other information do you need to help give me advice? Any measurements required?

    Thanks for looking.
    '98 GT Backwoods

  2. #2
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    Would a Chain wheel like this fit? Are their different sizes in crank spiders?

    MCS BMX 110mm 36T Single Speed Alloy Chainring Sprocket Chainwheel Cycle Bike | eBay
    '98 GT Backwoods

  3. #3
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    Ddd
    Last edited by 1SPDBING; 03-16-2014 at 05:36 PM.

  4. #4
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    Quote Originally Posted by 1SPDBING View Post
    I'd just take that chain ring into your LBS. That way you/they have something to compare to.

    What are you thinking of for the cog?
    A 18 or 20t might not be bad, but that depends on what tooth count you can get for the chain ring.
    Surly is a good option for the chain ring and cogs, (stainless,durable,and shinny) and they're reasonable priced. The cogs aren't stainless though but will hold up well.
    Hi 1SPDBING,

    In my 'test running' with my gearie, I can ride 32/15 (2.13) easily, I feel I need something more challenging. 32/13 (2.46) is good too, but I haven't tested it enough from a dead stop to come to a conclusion.

    36/16 (2.25)
    38/16 (2.37)

    ^that would be somewhere in the middle. The only problem is, I'm not sure how either of those ratio's will feel out of a dead stop or how fast they will let me ride (traffic lights; urban road riding; 7 miles, one way). I'll need more test runs on the 2.4 ratio. I use my 42t/13 & 15t (3.2 & 2.8) when on the road, but I would think it's too much torque/stress on the crank? Correct me if i'm worrying too much.

    Basically I'm in a dilema of wanting to have a decent top speed and movability.
    '98 GT Backwoods

  5. #5
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    i believe those were 94mm bcd, lots of aftermarket rings to choose from. blackspire mono veloce is a good option too.
    everything sucks but my vacuum cleaner.

  6. #6
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    Quote Originally Posted by fishcreek View Post
    i believe those were 94mm bcd, lots of aftermarket rings to choose from. blackspire mono veloce is a good option too.
    I believe you are right. How did you know? You're good!

    What does a 94mm BCD mean for me? Is it a good starting point for a SS build?



    Edit: Thinking about it some more...I don't think tenths of an increase in ratio will dramatically change anything. I should be looking for something closer to 3:1 right?

    Might even try the 42t/17t (2.4) for a while. How would I bolt up the 42t chain wheel pictured above if it doesnt have threats? I figure I would need a nut/bolt setup. What are they called for chain wheels?
    '98 GT Backwoods

  7. #7
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    Ddd
    Last edited by 1SPDBING; 03-16-2014 at 05:36 PM.

  8. #8
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    Thanks, very helpful.

    I've never shopped online for parts before, but what are some good sites to purchase parts such as chain ring bolts/nuts? I'm guessing steel would be good and not hurt the bank like Ti.


    I'm think about purchasing a LX/XT crank before purchasing a chain ring. I don't see a lot of options for 94mm. (bash guards, chain ring sizes)
    '98 GT Backwoods

  9. #9
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    Ddd
    Last edited by 1SPDBING; 03-16-2014 at 05:37 PM.

  10. #10
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    Ddd
    Last edited by 1SPDBING; 03-16-2014 at 05:37 PM.

  11. #11
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    '98 GT Backwoods

  12. #12
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    Quote Originally Posted by adrianm1188 View Post
    That's a simple question that involves a detailed answer.

    Cranks and bottom brackets (BBs) need to work together. The bike industry, being so fixed on standards, has several. What you have now is a square taper BB and crank. The BB screws into the frame, the axle is part of the BB and the cranks bolt to those axles. The first one you list above use an external BB where the cups screw into the frame and the bearings sit outside of the frame, then the crank has the axle attached and that slips through the BB and the other crank arm bolts to the other end of the axle.

    So, yes, the first will work, you will need to replace the BB as well though because what you have isn't compatible with those cranks.

    An important disclaimer...

    Truvativ external cranks use a spindle that tapers from 24mm to 22mm, so you need to use a Truvativ or SRAM BB. The first ad shows the crank coming with a Race Face BB. Race Face BBs are 24mm-24mm and therefore not cross compatible with Truvativ cranks, as I understand. Someone should correct me if I'm wrong, but that's my recollection.

    Also, there are 2 BB shell widths, 68mm and 73mm (there are others, but for MTBs, lets stick with 68mm and 73mm). The external BBs are set up for 73mm, but will come with spacers to make them fit a 68mm shell. If you buy second hand, make sure you get those spacers.

    The second one, the Deore, is a square taper like what you have now and also comes with a BB. Should be an easy swap if the BB is the right shell width (or you have spacers).

    In my usual fashion, that's probably clear as mud?

    Grumps

  13. #13
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    Very clear. I agree, I've been researching the stylos compatibility all morning. The race face bob is useless to me, like you said, leaving me with a GXP bottom bracket. I've been reading negative reviews on the SRAM bb due to 1) lack of seal protection and 2) durability.

    The Handful of negative reviews makes me lean towards a shimano non tapered crank set...which sucks because the truvativ are a sweet deal if it wasn't for the bb selection.

    Unless of course I have other bb options without breaking the bank. Trying to keep a budget build. Stylo would have been perfect. Thanks for you detailed reply.
    '98 GT Backwoods

  14. #14
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    if you want a solid setup just over $100, i will recommend:

    Shimano Deore M590 Triple Chainset | Buy Online | ChainReactionCycles.com

    Blackspire Mono Veloce Single Speed 7075 Series 2013 | Buy Online | ChainReactionCycles.com

    I have used Raceface, SRAM/Truvativ, and Shimano external bb cranksets before. I like the Shimano the most because of its ability to set the bearing preload. I had no issues with the others but I believe bearing life is dependent on the preload, just like headsets.
    everything sucks but my vacuum cleaner.

  15. #15
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    I'm thinking of getting a XT group deal for around 150$. M752 crank and ES-71 BB (71mm/118mm) along with some extras like XT v-brakes and derailleurs. My frame has a 71 shell, so it should work.
    http://www.jensonusa.com/images/Defa...2/CR707A10.jpg
    Similar to that. Different chain ring though...from a m760. Odd, but whatever.
    http://www.performancebike.com/image...41-015-TOP.jpg
    That sound like a good deal?
    Last edited by adrianm1188; 06-02-2013 at 06:42 PM.
    '98 GT Backwoods

  16. #16
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    $150 is alright if the parts aren't shagged out, though you're paying for derailleurs that you won't use on this project, which isn't to say that there's no merit in hoarding parts for later projects. I'm kind of guilty of that, tee hee...

    The crank is an Octalink model, nothing inherently wrong with that except external BB and crank designs are more current technology and supported by a range of BB options, such as Hope or Chris King.

    I'd be going with a singlespeed specific chainring, such as a Surly or a Blackspire Mono Veloce. I've used both and the Surly is my favourite for longevity. There is nothing wrong with using a chainring with shifting ramps and pins, (it's not as if the chain is going to derail) but the singlespeed specific rings are cleaner to look at. Just me being pedantic, I totally think that the best thing is to get the bike built and on the trails and then fine tune the spec as you get it dialed in.

    Just to make your life that little more difficult, consider crank length (ie: 170, 175 or 180mm).

    There are threads on that topic with some people favouring longer cranks for leverage and some going for shorter cranks. You make your own mind up as to what would work for you. I only raise it so your aware that there are differences and you pick what's right for you.

    Grumps

  17. #17
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    Thanks. I'm still trying to figure out WHY i'm trying to replace my square taper BB. I think i've caught the 'bug' that makes you want to be up to date/light weight with everything.
    Last edited by adrianm1188; 06-03-2013 at 11:38 AM.
    '98 GT Backwoods

  18. #18
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    Well, I think i'm going to stick with Square taper. Probably a XT m737 paired with a UN54 BB for reliability. Hopefully its not heavier than what I have now.


    -Bike weighs 29lbs with full drivetrain. I'm assuming its the a) rock shox indy S fork b) mavic x138 wheels c) Suntour x300 Square tapered BB. Right now, I just want to find a fork that will get rid of the heavy suspension.
    -What is available to me besides a Surly 1x1?

    I've seen some zaskars converted into roadies and I kinda like the idea. A rigid fork, thinner tires (currently have 1.9" Tioga city slickers), and larger chainwheels.


    I really like that idea combined with a SS drive train. Just need to figure out what fork I need.
    Last edited by adrianm1188; 06-15-2013 at 07:33 PM.
    '98 GT Backwoods

  19. #19
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    I would like something light and durable. But doesnt have to be top of the line. Anyone know what measurements I need for a rigid fork? I'm wouldnt ask if I haven't searched. But its difficult to search this site.

    Current Fork Measurements: RockShox Indy S
    Crown to axle = 17" - 17.5" / 435mm
    Steering tube = 9.5"
    Travel:....48mm haha no wonder it felt so low and difficult to do wheelies!

    The geometry of the bike itself is sits pretty low in the front as is. Would a 100mm be overkill?
    Last edited by adrianm1188; 06-15-2013 at 09:16 PM.
    '98 GT Backwoods

  20. #20
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    Alright. So it appears Chro-mo is the best option...


    Any recommendations other than Surly? Seems kinda short @ 413mm. My 48mm travel Indy S measures at around 435m.
    Last edited by adrianm1188; 06-15-2013 at 11:02 PM.
    '98 GT Backwoods

  21. #21
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  22. #22
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    Hey thanks! They look great.

    I have similar handle bar setup like yours; do you ever get shoulder pain? Sometimes I feel they're too low/over the front and maybe a riser bar or shorter stem might help. Currently have Kore Lite straight bar and 100mm stem.
    '98 GT Backwoods

  23. #23
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    Bike too small for me?




    Top Tube - 23"-23.5"
    Seat tube to center of TT - 20"
    Stem - 100mm 70*/30*
    Headset angle - 72*-73*
    Seat is pushed towards back on rail clamp.
    Last edited by adrianm1188; 06-24-2013 at 11:35 PM.
    '98 GT Backwoods

  24. #24
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    is that a 20" wheels??? holy, that's already an XL frame.. maybe its time to consider a 29er.
    everything sucks but my vacuum cleaner.

  25. #25
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    yea...but it was only 90$!

    What would you recommend? I mainly use it to commute 14 miles round trip. I didn't want to drop 400$ on a new bike.
    '98 GT Backwoods

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