Updating a 2007 Hotrock 24 and 2003 Hotrock 20?- Mtbr.com
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  1. #1
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    Updating a 2007 Hotrock 24 and 2003 Hotrock 20?

    I just scored a 2007 Specialized Hotrock 24 on Craiglist for $45. The bike is in good condition and I think I got a bargain.

    This bike is the 7 speed version. I was hoping to swap out the drivetrain and put a SRAM X? group on it with a 8 speed freewheel. I was expecting the addition of a front mech to be straight forward as there is a triple chainring version of this bike. However on checking closer I see that there are no cable stops for a front mech so it looks like the frames are different or perhaps I missed something?

    So has anyone converted a Hotrock 24 7 speed to a 2x8 ? How'd you handle the front mech?
    Last edited by TheNormsk; 01-04-2012 at 01:58 PM. Reason: Changed the title as the thread has drifted off the original subject.

  2. #2
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    Looking closer at the Specialized archive it would appear that the 7 speed and 21 speed version of this bike use different cable stops even though everything else looks identical.

    So I looks like I and stuck with a potential 8 speed for now.

  3. #3
    GMF
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    You want something like this:
    Problem Solvers 07' Backstop at JensonUSA.com

    Or you could go with a big range internal rear hub (alfine11?)

  4. #4
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    I used an Origin 8 cable stop for my son's Hotrock 20". Nice score, btw. I just bought a crappy Walgoose bike for $45, as I'm building up a XS 26" for my son, he can tool around on that.

    For my son's Hotrock 20, which was a 6 speed, I built a cassette rear wheel for it, and am running it 2x8. It's not unheard of, and probably more common than you might think in these parts (mtbr.com).

    I had initially put on a 7sp freewheel. While it did fit, shifting was not right and never was right.

    I wouldn't use the 8sp freewheel. First, it won't fit, and you will need a new hub anyway. Second, it's weaker than a cassette hub, and if you need to build a wheel, might as well go cassette.

  5. #5
    GMF
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    For the rear wheel, I was actually able to grab an old 8sp shimano RSX hub i had in the tool box and relace the wheel with that hub. Straight drop in (as much as any wheel build is a "drop in"). Not for everyone, but an option for some. Now he has pretty quality index shifting with some rapidfire shifters. With the 11-32 8sp cassette and a 32t chainring, that seems to have all the range he needs right now. When we put some more miles on, that opinion might change.

  6. #6
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    I found the Origin8 on Amazon. Much more affordable.

    I'm still trying to work out what to do drive train wise on this bike, but I ended up moving the thread to the drivetrain forum.

    You have me a little worried now though as I also got my son a Hotrock 20 for $45 and I have already ordered a 7-speed freewheel for that and shifter as someone else said they did it with no problems, yet you said you did have issues. The parts should turn up tomorrow, so wish me luck.

    My daughter's Hotrock 24 really is in excellent condition, bearings are smooth, drivetrain works okay - just needs a tune up. I may just leave it that way for now, as I may update it to a 2x8 using 90's spec XT/XTR components I may take off my mountain bike when I upgrade my drivetrain to a 2x10. That may be the time I take up wheel building as a summer hobby.

  7. #7
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    note, my son's Hotrock 20 is one with 130mm dropouts. In later years they went to 135mm. I'm not sure if it helps or changes anything. I used a Shimano Tiagra (sp?) hub on it.

    My shifting issues were in the middle gears that I couldn't dial out, when adjusting for the 7sp range. Either I'd get the middle gears and get clicking on the lower gears or vice versa. It would shift, it would just click constantly in certain gears.The freewheel is larger (stack height) than the 6sp freewheel it came with. The same 7sp freewheel on my daughter's GT Scamp 20 is fine, as it was 7sp to begin with.

    One thing to concern yourself with, as you upgrade. Long cage derailleurs on a 20 inch bike is not such a good idea. It's long, and can bend easily if your son crashes. A short cage would be nice, but it gets into more expensive gear, and not as easily replaceable. Since I run my son @ 2x8, mid cage (SRAM) was all I could go for, and even then, it's bent a derailleur or two. I'm thinking a 1x9 would be better with the 12T-36T cassette, with loss of choices in between gears. My son runs 22T front mostly in the front on trails, for the climbs, and shifts through the 8 in the back. He uses the 32T front for street and park-ish/dirt trails. He doesn't have the strength to trail climb with 32T+32T.

  8. #8
    GMF
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    Quote Originally Posted by IAmHolland View Post
    He doesn't have the strength to trail climb with 32T+32T.
    This is interesting to me. Does he have the balance to maintain a 22-32? I'm guessing so, since that is what he uses.

    Like i mentioned about my son's setup, we don't have a lot of miles on it, so time will tell if the 32-32 will work, or if we'll need to adjust things.

  9. #9
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    Quote Originally Posted by GMF View Post
    This is interesting to me. Does he have the balance to maintain a 22-32? I'm guessing so, since that is what he uses.

    Like i mentioned about my son's setup, we don't have a lot of miles on it, so time will tell if the 32-32 will work, or if we'll need to adjust things.
    Yes, it works well, albeit slow. He's 7yo, and has been using it since he was 6yo, but riding since 2yo. He does have good balance in any sport he picks up. I am trying to get him to go to a higher gear, to build up strength, and to work on cadence as he blows up now and then. He is getting stronger, able to go up hills he couldn't make a week or two ago, as an aside. These are hills I have a really hard time going up on my SS, full tilt mashing for me and wiggling to not topple over as I stall out now and then.

    I will see with my daughter how it works, as I can't say generically if it applies. She doesn't have the balance my son does, but is more graceful and fluid. I will be moving his setup to her bike.

  10. #10
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    The Hotrock 20 that my son has has the 130mm rear spacing, so it looks like i may be in a dilemma. If it doesn't work on my son's bike i can always use this to put trigger shifting on my daughters Hotrock 24 for now until I figure out something longer term.

    I see that the Tiagra hub is 130mm spacing and can run 9-speed. May I ask what rim and spokes you went with and did you build the wheel yourself?

    I must admit that going 9 speed gives more options, though I fear it is a more expensive pursuit...

  11. #11
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    Quote Originally Posted by kerryn View Post
    I see that the Tiagra hub is 130mm spacing and can run 9-speed. May I ask what rim and spokes you went with and did you build the wheel yourself?

    I must admit that going 9 speed gives more options, though I fear it is a more expensive pursuit...
    I went with the Velocity Aeroheat 20" rim. Spokes were just ebay steel spokes, cut to order. Nothing fancy, as getting spokes that short is difficult to impossible in the ultra lightweight spokes from DT Swiss or other manufacturers.

    You'll need to use a spoke length calculator with dimensions of the rim, and the hub to get the spoke lengths you need. I used the calculator on the DT Swiss website.

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