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  1. #1
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    Started modding a Hot Rock 24"

    Picked up a Hot Rock 24" A1 FS a while back on eBay for $200...nearly new. Its the 2009 model. Nice little bike. So far I have replaced the bar/post/stem with the ones off my Stumpjumper..much lighter. I yanked the chainrings and replaced with a single 33T off the Stumpy as well as the E.13 chain guide to run it 1x7. I rebuilt the Suntour fork as it was sticky..man....that spring is WAY to stiff for a 70lb kid! So that is where I am at..the bike is lighter and more functional now. Went riding yesterday for the first time and he had fun but had to walk some of the small hills. Here are some questions:

    The gearing isn't quite low enough for him so I am thinking of either a smaller f. chainring or going with a different r. hub/wheel so I can run a 10-speed cassette. Do you think I am better off just buying a 10-speed hub and re-lacing it to the rear rim or just buying a new set of wheels? I suppose I could go disc if I replaced the wheels...I have a set in the parts bin but I hesitate as this bike is just a 'hood beater and I would hate for him to toss it down and hose a set of decent hydro disc brakes.

    Does anyone know of aftermarket springs that are softer than the OEM in the Suntour Fork?

    Anyone set up these 24" wheels ghetto tubeless?
    Geologist by trade...bicycle mechanic (former) by the grace of God!

    2012 Specialized Stumpy EVO 29 HT

  2. #2
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    all depends how much you want to spend

    there are no softer springs for the 24 inch suntour forks which is why I bought Lewis an air fork. The gearing on the back of his bike could be larger but you can get SRAM 7sp cassettes that have 32t rather than the 28 he currently has. Lewis's bike came with mechanical discs but these where junked straight away cause they were crap for some elixir 3's that were going cheap.

  3. #3
    turtles make me hot
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    I put a 26er fork on my son's 24" bike. Works fine.
    I also used Ebay Avid Elixrs.
    His bike is set up 1x10. 11-36 on the rear and a 34 tooth up front. Works great.
    I like turtles

  4. #4
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    Quote Originally Posted by POAH View Post
    all depends how much you want to spend

    there are no softer springs for the 24 inch suntour forks which is why I bought Lewis an air fork. The gearing on the back of his bike could be larger but you can get SRAM 7sp cassettes that have 32t rather than the 28 he currently has. Lewis's bike came with mechanical discs but these where junked straight away cause they were crap for some elixir 3's that were going cheap.
    Thanks for the info. His cassette is already the "Mega Range" with a 34T so a 36T or even one of the 42T adapters for a 10-speed cassette is the next step. I can also get a 30T ring. I have a set of Elixir 3s sitting around...I just worry if they are goofy off in the 'hood that discs won't be as durable to dropping etc.....I can see a bent rotor. What wheels did you use?
    Geologist by trade...bicycle mechanic (former) by the grace of God!

    2012 Specialized Stumpy EVO 29 HT

  5. #5
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    Quote Originally Posted by NYrr496 View Post
    I put a 26er fork on my son's 24" bike. Works fine.
    I also used Ebay Avid Elixrs.
    His bike is set up 1x10. 11-36 on the rear and a 34 tooth up front. Works great.
    What wheels are you running? I have seen another thread (older) where someone was running an older RS SID 63mm travel 26" fork with no issues. I would probably just go rigid.
    Geologist by trade...bicycle mechanic (former) by the grace of God!

    2012 Specialized Stumpy EVO 29 HT

  6. #6
    turtles make me hot
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    Quote Originally Posted by TiGeo View Post
    What wheels are you running? I have seen another thread (older) where someone was running an older RS SID 63mm travel 26" fork with no issues. I would probably just go rigid.
    I built him a set of Sun Ringle Rino Lytes on Shimano Deore hubs.
    I like turtles

  7. #7
    try driving your car less
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    We have the same bike. I changed the bar stem seat post. Also ti BB because I had that stuff. Ours is also something I don't want to invest a lot into. Wheels seemed too expensive so I left the triple and did not go with the cassette and disc upgrade. I am still on the fence about putting in an air fork.
    I did remove the spring from one side of the fork and it is softer but still very sticky.

    The bike I have is older so may be different. I am saving the big upgrade for the 26" wheel bike.
    Only boring people get bored.

  8. #8
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    Quote Originally Posted by TiGeo View Post
    Thanks for the info. His cassette is already the "Mega Range" with a 34T so a 36T or even one of the 42T adapters for a 10-speed cassette is the next step. I can also get a 30T ring. I have a set of Elixir 3s sitting around...I just worry if they are goofy off in the 'hood that discs won't be as durable to dropping etc.....I can see a bent rotor. What wheels did you use?
    wheels where on the bike already with discs - He bent a lever on the bike somehow but that's all and they get used to the difference in power quickly.

  9. #9
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    ^^^Didn't think about just removing the spring from one side, may try that.
    Geologist by trade...bicycle mechanic (former) by the grace of God!

    2012 Specialized Stumpy EVO 29 HT

  10. #10
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    Definitely try the one side spring thing. I did a lot of mods on my son's 20" Suntour sprung fork and it works pretty well for what it is. Some people changed out the springs for elastomers which was also successful. I've included the link to the mod for the 20" but it may help you with ideas on the 24" fork.

    Increasing SR Suntour 40mm travel fork to 60mm

    Another alternate recommendation I'll make is to buy the RST F1rst Air 24" fork. They are hard to find but they are the real deal. I bought my son a 2014 Scott Scale RC Jr which had the Suntour Air fork and it uses an air cartridge type system. The RST uses a true oil bath, shim stack dampened system. It allows you to use significantly lower air pressures to get the right feel out of the fork. If you do go with a 26" fork, try and find one that uses air for the negative spring, such that you can adjust it accordingly for his weight. Otherwise you will find yourself trying to find a lighter negative steel spring. Hopefully that makes sense.

    As for the gearing, I would change the rear out to a 10spd with a 36T cog if you can. You can do it a few different ways. I went the lazy route and bought the XT drive train.

  11. #11
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    I am going to see what one of the shops in town will charge for a Deore or X7 rear 10-speed hub and the labor to lace it to the existing rim..no need to do anything more than is necessary. I have a 10-speed cassette, chain,and 32t Wolf Tooth ring sitting around...why not? I will also need a new r. deraileur thinking X7 Type 2.
    Geologist by trade...bicycle mechanic (former) by the grace of God!

    2012 Specialized Stumpy EVO 29 HT

  12. #12
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    can get the first air 24 from bike-discount

    RST F1RST Air 24" MTB Federgabel schwarz

    and it's black not white

  13. #13
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    Set it up tubeless today. Gorilla tape method seems to be holding air just fine. Down to 24.5 lbs for basically free. I think it started around 28.

    Sent from my SCH-I545 using Tapatalk
    Geologist by trade...bicycle mechanic (former) by the grace of God!

    2012 Specialized Stumpy EVO 29 HT

  14. #14
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    Ok...the tubeless was a fail. After a few days it lost air (not uncommon after the initial setup) and when I tried to re-inflate, the tires look to have stretched (they are wire-bead...not good for tubeless). Went back to tubes. On the fork, I removed the spring and lock-out gear from the right side and it is softer and has less stiction so that seems to have worked.
    Geologist by trade...bicycle mechanic (former) by the grace of God!

    2012 Specialized Stumpy EVO 29 HT

  15. #15
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    Silly me...forgot a pic!
    Attached Thumbnails Attached Thumbnails Started modding a Hot Rock 24"-20140125_095354.jpg  

    Geologist by trade...bicycle mechanic (former) by the grace of God!

    2012 Specialized Stumpy EVO 29 HT

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