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  1. #1
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    Cheap easy upgrades for a Hotrock 20

    Just ordered my son a new hotrock 20
    Specialized Bicycle Components
    I'd like to do some quick easy upgrades to lighten up the bike a bit since I hear changing out the handle bars and seatpost can lighten the bike up by 1lb alone.
    I'm recently getting back into biking and don't know what I should get. These and any other upgrades I'd like to keep under $100.

    I also am curious about changing the grip shift to a normal click shifter, and was wondering if there is any problem doing that on a kids bike.

  2. #2
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    One quick fix to lighten up the bike is to remove the kick stand.

  3. #3
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    Saddle
    Crankset..this might be a tough one unless you're patient waiting for deals but the stock crank and chainguide hare quite beefy. Sinz and AC among others make child appropriate length cranks.
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    Does anyone know if the fork has a lock out?

  5. #5
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    Quote Originally Posted by flippedr6 View Post
    Does anyone know if the fork has a lock out?
    I can't speak for the current year, but in the past there's been no lockout or any other adjustments. The front forks are boat anchors so his bike can look like dads.

  6. #6
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    Here is the fork info
    SR Suntour SF9-XCT-JR-20, 1pc alloy lower, coil/MCU spring, 1-1/8" Hi-Ten steerer, direct press type dust seal, for both V+Disc brake mount, preload adjust, 40mm travel
    So it does have preload adjust.

    Also...
    SRAM X9 9-speed drivetrain (der., shifter, cassette)
    Would I have a problem putting these things on his bike? I was just looking for a shifter at first, but this caught my eye. In several years I could always move it to the new bike I get him.

  7. #7
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    Quote Originally Posted by Fastblack View Post
    Just ordered my son a new hotrock 20
    Specialized Bicycle Components
    I'd like to do some quick easy upgrades to lighten up the bike a bit since I hear changing out the handle bars and seatpost can lighten the bike up by 1lb alone.
    I'm recently getting back into biking and don't know what I should get. These and any other upgrades I'd like to keep under $100.

    I also am curious about changing the grip shift to a normal click shifter, and was wondering if there is any problem doing that on a kids bike.
    My sons do much better with click shifters as compared to grip shift. No prob, but I'm using an 8spdshifter w/7spd and cheap 7 w/7.

  8. #8
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    Quote Originally Posted by Fastblack View Post
    Here is the fork info
    SR Suntour SF9-XCT-JR-20, 1pc alloy lower, coil/MCU spring, 1-1/8" Hi-Ten steerer, direct press type dust seal, for both V+Disc brake mount, preload adjust, 40mm travel
    So it does have preload adjust.

    Also...
    SRAM X9 9-speed drivetrain (der., shifter, cassette)
    Would I have a problem putting these things on his bike? I was just looking for a shifter at first, but this caught my eye. In several years I could always move it to the new bike I get him.
    I'm still a noob wrt to wrenching, but I'm pretty sure your hotrock is a freewheel, not a cassette, so this won't work for you.

  9. #9
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    I've done a fair bit to my son's 20" hotrock. It is now using cut down old cannondale cranks, and a 2x8 drivetrain among other mods. The seatpost wasn't too bad, but the handlebars and chain guide are pretty ridiculous (heavy steel) and are easily the first things to go. I'm looking for a cheap way to upgrade the front fork, too, because that thing is also a tank, although it does take up the big hits for him (certainly not plush).

    If you are planning on doing proper mountain biking, reducing the gear ratio is pretty important (freehub first, crankset second), but should be OK for general street riding.

  10. #10
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    Is there anything easily compatible to make it a 1x9 speed? I do want to take him out on the trails eventually.
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    Shorter cut-down seatposts can be cheap, as are shorter carbon bars (since most everybody wants wide bars). I picked up a short carbon seatpost for my daughters hotrock 20, the post is too short for any of my bikes but good for her bike. Plus, I put some old alloy bars on there, and really thin grips since her hands are small. I have a DH pad on the top tube, and a pad on the stem. I think we're good for now, I expect her to outgrow it within 2 years so I don't want to put too much into it (I have a pink hotrock24 standing by in the bsmt, then she'll get her brothers 13" Klein Pulse 26er). I would have gotten the Hotrock Street with the lighter rigid fork if I had not found this first. With kickstand it's about 24# even, - probably 10 pounds lighter than the Schwinn I was riding as a kid in the early 70s. When she gets a little more aggressive on the trails, I'll remove the kickstand, but she likes it for now.

  12. #12
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    Weigh the tire and see what it comes in at- stock tires are normally bricks.

    It's a 7 speed RD so you can add a mega range freewheel for a nice low climbing gear. Added one to my daughters Shred 20 and it helped a lot. On a 20inch bike I wouldn't put much more in and save the money for the 24 inch since kids are on them longer.

    Amazon.com: Shimano MF-TZ31 Tourney Freewheel (14-34T Mega 7 Speed): Sports & Outdoors
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  13. #13
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    The 2014 model is showing these specs for the rear.

    REAR DERAILLEURShimano, 6-speed, short cage
    SHIFT LEVERSShimano RS-35, 6-speed, Revo Twist
    CASSETTE Shimano, 6-speed freewheel, 14-28

    So I'm assuming I would need to replace everything, in which case why not go 9 speed right?
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  14. #14
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    Absolutely right, but what you aren't seeing there is that you won't find a 9sp freewheel. You'll need to either swap out the rear hub or build a whole new rear wheel to use a modern cassette.

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    Gotcha. So going 7 speed is the best I can do without putting a ton more work into it then?
    Thanks for all the help by the way.
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  16. #16
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    Check ebay for some cheap XT 8 speed stuff
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  17. #17
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    Quote Originally Posted by TwoTone View Post
    Check ebay for some cheap XT 8 speed stuff
    Yeah, but (I could be wrong), 8spd=cassette; right now, he's got a freewheel. So fastblack, unless I'm wrong, that involves buying a new rear hub plus the cogs, AND building a new wheel. I would imagine that if you got a shimano hub you could re-use the spokes and rim, but otherwise you have to figure out spoke length. I'm hoping to build a rim one day soon, but it seems somewhat difficult, and it's certainly expensive to have somebody else do it.

    I'd get the mega-range freehub (and tool) from amazon, keep an eye on craigslist for cheap carbon bars/seatpost/stem (use IFTT app--it's awesome!), and also keep your eye out for the 24" bike on which your kid might stay for a bit longer.

  18. #18
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    Quote Originally Posted by Vxc961 View Post
    Yeah, but (I could be wrong), 8spd=cassette; right now, he's got a freewheel. So fastblack, unless I'm wrong, that involves buying a new rear hub plus the cogs, AND building a new wheel. I would imagine that if you got a shimano hub you could re-use the spokes and rim, but otherwise you have to figure out spoke length. I'm hoping to build a rim one day soon, but it seems somewhat difficult, and it's certainly expensive to have somebody else do it.

    I'd get the mega-range freehub (and tool) from amazon, keep an eye on craigslist for cheap carbon bars/seatpost/stem (use IFTT app--it's awesome!), and also keep your eye out for the 24" bike on which your kid might stay for a bit longer.
    You're not following, get the mega range freewheel and the rest of it on Ebay cheap. You can make an 8sp RD work on the Freewheel. The stock RD won't work.
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  19. #19
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    Quote Originally Posted by TwoTone View Post
    You're not following, get the mega range freewheel and the rest of it on Ebay cheap. You can make an 8sp RD work on the Freewheel. The stock RD won't work.
    Oops, you were right, I didn't follow. Why won't the stock 7spd rear dérailleur work? I had actually picked up an old 8spd derailleur, but it's a long cage, and I'm worried about ground clearance on those 20" tires!

  20. #20
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    Quote Originally Posted by Fastblack View Post
    The 2014 model is showing these specs for the rear.

    REAR DERAILLEURShimano, 6-speed, short cage
    SHIFT LEVERSShimano RS-35, 6-speed, Revo Twist
    CASSETTE Shimano, 6-speed freewheel, 14-28

    So I'm assuming I would need to replace everything, in which case why not go 9 speed right?
    Quote Originally Posted by Vxc961 View Post
    Oops, you were right, I didn't follow. Why won't the stock 7spd rear dérailleur work? I had actually picked up an old 8spd derailleur, but it's a long cage, and I'm worried about ground clearance on those 20" tires!


    I saw the above post and thought perhaps you had linked us to a 2013 bike by mistake. Looks like the 2014 does come with a 7sp RD. Now not all 7sp RD can handle a large cog so you may still need to swap it.
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  21. #21
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    My original link actually was the 2013 model. Here is the 2014 that I actually ordered.
    Specialized Bicycle Components
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  22. #22
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    Quote Originally Posted by Fastblack View Post
    My original link actually was the 2013 model. Here is the 2014 that I actually ordered.
    Specialized Bicycle Components
    Ok so it does comes with a 6sp RD.
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  23. #23
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    So I'll go with that 7 speed freewheel. What derailer and shifters would you recommend?
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  24. #24
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    Quote Originally Posted by Fastblack View Post
    So I'll go with that 7 speed freewheel. What derailer and shifters would you recommend?
    My kids did better with triggers over grip.

    It really depends on what you want and how soon. I bought a cheap tourney RD and Shifter on Amazon, all the while keeping my out for a good deal used on EBAY.

    I picked up a used Short Cage XTR RD for $40
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  25. #25
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    Ok,
    So I found this freewheel in the 13-32 config. I know this one costs more but I'm really hesitant to get the shimano mega range one because of the huge difference in gearing, this is more subtle and I think it would be better.
    Defiant Freewheels, 7, 6, and 5 speeds

    Here is a derailuer that should work well.
    Amazon.com: Shimano Tourney TX75 6/7 Speed Rear Derailleur: Sports & Outdoors

    And the shift here
    Amazon.com: Shimano Acera SL-M310 Rapid Fire Shifter, Right (Black, 7-Speed): Sports & Outdoors

    Do all of these seem like decent choices?
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  26. #26
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    Freewheel - sure.
    Shifters - either 7 or 8ap will both work (the tooth to tooth pitch on 7sp is essentially identical, 8sp is just wider)
    Dérailleur - why switch? I think the stock one should work, right? It is the shifters that determine cassette compatibility, not the derailleurs (within all shimano, that is)

  27. #27
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    Quote Originally Posted by GMF View Post
    Freewheel - sure.
    Shifters - either 7 or 8ap will both work (the tooth to tooth pitch on 7sp is essentially identical, 8sp is just wider)
    Dérailleur - why switch? I think the stock one should work, right? It is the shifters that determine cassette compatibility, not the derailleurs (within all shimano, that is)
    Not true, that 6spd RD I seriously doubt will fit the 34 cog. I researched some of the XT RDs on Ebay and the max cog was 32.

    OP those look like the ones I got, not great, but good enough. I have them adjusted well enough my daughter doesn't have problem. Just make sure that RD can handle the 34 cog.
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  28. #28
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    So I thought I was set on what I was getting until I came across these Sunrace 8 spd and 9 speed freewheels.

    Any reason these wouldnt work?

    Amazon.com: Sunrace 8-Speed Freewheel 13-34: Sports & Outdoors

    Amazon.com: Sunrace 9-Speed Freewheel 13-32: Sports & Outdoors

    Amazon.com: SunRace 8-Speed 13-32 Freewheel Chrome: Sports & Outdoors
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  29. #29
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    8/9 speed FW require a longer axle extension on the drive side in order to make room for the additional cogs (the Freewheel is approx 5-6mm wider than a 6 or 7 speed). If the frame dropouts are not at least 130mm or more (preferably 135mm), then adding a 8 or 9 speed FW will require re-dishing the rim/spokes excessivly far over. On an adult bike, 8/9 speed freewheels result in a weak wheel and broken axle but likely could survive under a kid.
    In my experience, a kid on a 20" bike does not need or use 8 or 9 speeds. My daughter has a 6-speed and I dont think she ever goes fast enough to need to shift higher than about 4th gear, she always just coast if she ever gets going fast enough to need a higher gear.

  30. #30
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    Quote Originally Posted by GrayJay View Post
    8/9 speed FW require a longer axle extension on the drive side in order to make room for the additional cogs (the Freewheel is approx 5-6mm wider than a 6 or 7 speed). If the frame dropouts are not at least 130mm or more (preferably 135mm), then adding a 8 or 9 speed FW will require re-dishing the rim/spokes excessivly far over. On an adult bike, 8/9 speed freewheels result in a weak wheel and broken axle but likely could survive under a kid.
    In my experience, a kid on a 20" bike does not need or use 8 or 9 speeds. My daughter has a 6-speed and I dont think she ever goes fast enough to need to shift higher than about 4th gear, she always just coast if she ever gets going fast enough to need a higher gear.
    Thanks for the info. I don't want to have to do that much work so I'll stick with the 7. I'm more worried about the low gear for climbing. Not so interested in top speed.
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  31. #31
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    Quote Originally Posted by Fastblack View Post
    Thanks for the info. I don't want to have to do that much work so I'll stick with the 7. I'm more worried about the low gear for climbing. Not so interested in top speed.
    It will be fine. Same with my daughter, she has never hit the higher gears and the 34 lets her climb anything she needs to.
    Not a close up, but here is the set up on her bike: Daughter's 6th birthday build
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  32. #32
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    Got the bike today and am going to be ordering everything now. Something I wasnt thinking of the whole time... Do I need a new chain?
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  33. #33
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    Quote Originally Posted by Fastblack View Post
    Got the bike today and am going to be ordering everything now. Something I wasnt thinking of the whole time... Do I need a new chain?
    I didn't, RD, Freewheel and shifter
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  34. #34
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    I used one of these 8 speed freewheels, along with a Sram X9 short cage RD, and X7 gripshift, along with a new KMC (don't remember the model#) chain. My 7 year old has a much easier time shifting now.

    Gathering parts to convert my friends daughters Diamondback gripshift. I can hardly turn it to the two lower cogs myself!
    It amazes me lack of quality on even Sporting goods store quality bikes.
    I used to tell people the Diamondbacks from ***** were a step above Walmart bikes, but wonder now. We have a little 20" Diamondback as a spare/loaner bike that works pretty good.

    Quote Originally Posted by Fastblack View Post
    So I thought I was set on what I was getting until I came across these Sunrace 8 spd and 9 speed freewheels.

    Any reason these wouldnt work?

    Amazon.com: Sunrace 8-Speed Freewheel 13-34: Sports & Outdoors

    Amazon.com: Sunrace 9-Speed Freewheel 13-32: Sports & Outdoors

    Amazon.com: SunRace 8-Speed 13-32 Freewheel Chrome: Sports & Outdoors

  35. #35
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    If you're looking to lighten things up, check out the tires and get Kevlar beaded Kenda SB8's or Scwalbe tires. Also the bottom bracket and crank assembly have a tendency to be very heavy. Check out using a 1x setup.

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    I just got my daughters hotrock back from recycled cycles a couple of weeks ago for my daughters 6 birthday and I had them build me a rear wheel out of old parts with a mega range 8spd 11-34(new), a chain (new), new cut to length spokes and a recycled derailleur,hub, and rim I had the rapid fire shifter pods, grips and a set of pink aluminum bars (wider and lighter). To build the wheel and set everything up after store credit for the parts that were removed from her bike I was out the door for $125 which is also the amount I paid for the bike used in the first place. That being said she now is making climbs on the trails that we ride that she would normally give up on about half way and as for the climbs she was just barely making she is blasting through them with tons of confidence. As the dad that would follow behind her and help push(dad turbo boost) her up hills that she wasn't clearing is priceless I also imagine these modded hotrocks should be easy to sell when our kids grow out of them.

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