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  1. #1
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    Gromhit for a 6-year old???

    Anyone who knos/have an idea about i the Specialized Gromhit may fit a 48" tall kid?

    Don't think I wil find at test bike here in Stockholm, Sweden....

  2. #2
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    Probably not

    Quote Originally Posted by PanzerGoose
    Anyone who knos/have an idea about i the Specialized Gromhit may fit a 48" tall kid?

    Don't think I wil find at test bike here in Stockholm, Sweden....

    I'd say your kid would need to be at least 54" to fit.

    Jake Wake

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    Ok, but if I change the wheels so he can use 20"-wheels...?

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    My son is exactly that tall and fits just about perfectly on his 2003 Hotrock 20 6 speed (he's grown quite a bit since the photo below was taken).

    Gromhit specs: http://www.specialized.com/bc/SBCGeo...jsp?spid=34374

    GromHit (edited to remove non-fit-critical stats)

    Seat Tube Length - Center to Top 381mm
    Top Tube Length (Horizontal) 514mm
    Top Tube Length (Actual) 499mm

    Chainstay Length 413mm
    Wheel Base 1089mm
    Standover Height 663mm
    Handlebar Width 620mm
    Stem Length 40mm
    Crank Length 165mm

    2003 HR 20 specs: http://www.specialized.com/bc/SBCGeo...jsp?spid=20981

    03 Hotrock 20 6-Speed Boys

    Stand Over Height 571mm
    Top Tube Length 505mm <<< top tube length plus VVV
    Wheel Base 864mm
    Chain Stay Length 420mm
    Stem Length 75mm <<< stem length actually makes my son's bike longer
    Handlebar Width 540mm
    Crank Length 160mm

    Also, you might have better luck finding a Hotrock 24 in a Stockholm dealer and having him test ride that. Go here for 2008 specs: http://www.specialized.com/bc/SBCBkM...=08HotrockBoys

    You could also get him the Grom Hit 24 and "shrink" it. Buy some used disc wheels with busted rims and rebuild them with 20" Rhyno Lites. If he gets too much crank strike with the 20's, get shorter crank arms. When he grows, replace the wheels and cranks with the 24's. (EDIT: I see you're thinking along the same lines.)

    I'm sure you know that Kona also makes a Stinky 24 (Stinky Jr is the old name in case you look for a used one on eBay or craigslist).

    Current bike: http://www.konaworld.com/08_stinky24_w.htm

    Specs: http://www.konaworld.com/bikes/2k8/images/geo/geo21.jpg

    The other issue you might consider is weight. Your son is what - 50 pounds? Most adult women are 100 pounds or more. Think about getting him an extra small women's trail bike and installing a 24" disc wheelset. It should be more than strong enough to handle anything a 6yo can do and will be easier for him to throw around than the Grom Hit and Stinky, which are beefy freeride bikes made for kids slightly larger than ours.

    Cost-no-object example: http://www.titusti.com/moto_women.html#geometry

    Another lighter-weight possibility might be an extra-small 24" hardtail with a really big rear tire and a suspension seatpost to take the edge off big hits, with maybe a 20" front disc wheel on a long travel trail bike fork (130-150mm).

    Good luck. I'm curious about your findings, so please update this thread when you find a freeride solution for your little ripper. I may or may not get a disc wheel / suspension fork setup for my son. It depends where he decides to take his riding.

    My kids: Stowe bike park 9/23/07: When kids attack

    Last edited by Fuzz541; 03-26-2008 at 09:38 AM.

  5. #5
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    No, no, no

    Quote Originally Posted by PanzerGoose
    Ok, but if I change the wheels so he can use 20"-wheels...?

    No - please don't do this. The bottom bracket would be so low that the cranks would hit the ground on the downstroke. You really can't do this.

    Jake Wake

  6. #6
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    Quote Originally Posted by JakeWake


    No - please don't do this. The bottom bracket would be so low that the cranks would hit the ground on the downstroke. You really can't do this.

    Jake Wake
    My son's rigid bike has a 250mm bb height with 160mm cranks and he rarely hits his cranks with the approximate 90mm low-pedal spindle height.

    The current HR 20 has a 50mm suspension fork, a 224mm bb height and a 127mm crank, for a 97mm low-pedal height.

    Dropping the Grom 51mm by putting it on 20" rims would give it a bb height of about 265mm and a low-pedal height of about 100mm without changing the 165mm cranks.

    Shorter cranks, narrower pedals, etc. etc. etc. I think he can pull it off if he's mindful of how each change affects the bike.

    Also, unless he's a freakishly gifted athlete, a 50-60# 6yo is going to have trouble fully compressing the suspension, which is likely designed for an 80-120# kid. Hence my thoughts on a tiny women's trail bike.

    Just my 2 cents.

  7. #7
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    Great Fuzz
    About the same analysis I've made. He is now riding a 20"-wheeled Kona Shred 2-0 most of the time. Mostly jumping and trailriding with me. I've realized he is talanted in technical riding and he really wants to go downhill with me. I can se that he is really charging the Shred in the downhill sections in a way that tells me that he would benefit from good working suspension.

    So, this is a bit of free thinking from my side. Look out for the thread in the DH/FR-forum. It's very lively. I've placed my thougts and questions there too.

  8. #8
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    Quote Originally Posted by Fuzz541
    My son's rigid bike has a 250mm bb height with 160mm cranks and he rarely hits his cranks with the 90mm low-pedal spindle height.

    The current HR 20 has a 50mm suspension fork, a 224mm bb height and a 127mm crank, for a 102mm low-pedal height.

    Dropping the Grom 51mm by putting it on 20" rims would give it a bb height of about 265mm and a low-pedal height of about 100mm without changing the 165mm cranks.

    Shorter cranks, narrower, etc. etc. etc. I think he can pull it off if he's mindful of how each change affects the bike.

    Also, unless he's a freakishly gifted athlete, a 50-60# 6yo is going to have trouble fully compressing the suspension, which is likely designed for an 80-120# kid. Hence my thoughts on a tiny women's trail bike.

    Just my 2 cents.
    Don't forget that this is a 5" suspension bike. Sag will take up another 1.5 in of your clearance. Plus when you corner and lean the bike your pedal gets even closer. I highly recommend against this, speaking as the designer of the bike.

    Jake Wake.

  9. #9
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    Heck, split the difference and just do a 20" rear wheel (like the old Big Hit 26/24 setup) along with the crank and pedal change.

    I may do a 24" front wheel with an 80mm fork on my son's bike. I'll bump this thread with an update if it ever happens.

  10. #10
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    Quote Originally Posted by JakeWake
    Don't forget that this is a 5" suspension bike. Sag will take up another 1.5 in of your clearance. Plus when you corner and lean the bike your pedal gets even closer. I highly recommend against this, speaking as the designer of the bike.

    Jake Wake.
    ORLY?
    Quote Originally Posted by Profile
    Morgan Hill, CA
    I defer to your expertise and then some.

    Tell us though, what IS the designed rider weight range for the bike? Can a 50# kid even get 1.5" of sag at the minimum settings? And what does the bike weigh?

    Thanks for your input - it's really cool to see a bike designer involved in threads like this (I know there are many industry folks on these boards, but I'm an infrequent user, so...).

  11. #11
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    Quote Originally Posted by Fuzz541
    ORLY?I defer to your expertise and then some.

    Tell us though, what IS the designed rider weight range for the bike? Can a 50# kid even get 1.5" of sag at the minimum settings? And what does the bike weigh?

    Thanks for your input - it's really cool to see a bike designer involved in threads like this (I know there are many industry folks on these boards, but I'm an infrequent user, so...).

    The rear shock is an air shock, so you can get the spring pretty light. The front fork is a custom Marz with an extra light coil spring and air assist. The purpose of the air shocks is so you can set the pressure very low when the kid is light, then add pressure as they grow (as opposed to buying new coil springs). Realistically, a 50# kid is not going to get much sag. That doesn't really change the fact that the bike has 5" travel, and the bike leans to corner, and you don't ride on flat terrain.

    Also, where are you going to find disk brake 20" wheels? It seems like a pretty spendy idea that you child will outgrow in 1 year.

    Jake Wake

  12. #12
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    I forgot to check the spec for an air shock. That answers that. He could run the bike in the "high" setting to add some bb height.

    My thought was that he could find bent disc wheels with Deore hubs (cheap and relatively durable, esp. for a kid) and build them with moderately priced Sun Rhyno or other quality 20" bmx wheels. $100 max if he's careful, and he can sell the wheels when his kid outgrows them.

    Again, what is the approximate rider weight range the bike is designed for (you stated a 54" height), and what is the overall bike weight itself?

    And good reviews: http://www.mtbr.com/reviews/Freeride...t_123215.shtml

  13. #13
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    Quote Originally Posted by Fuzz541
    I forgot to check the spec for an air shock. That answers that.

    My thought was that he could find bent disc wheels with Deore hubs (cheap and relatively durable, esp. for a kid) and build them with moderately priced Sun Rhyno or other quality 20" bmx wheels.

    Again, what is the approximate rider weight range the bike is designed for (you stated a 54" height), and what is the overall bike weight itself?

    And good reviews: http://www.mtbr.com/reviews/Freeride...t_123215.shtml

    Rider weight is approx 60 - 120 lbs. Approx. rider age 7-12. Bike weight out of the box is approx. 34 lbs.

  14. #14
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    Thanks! Panzer, good luck and tell us how it goes.

  15. #15
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    3 new Gromhit available

    The gromhit is getting harder to find because Specialized ran out of them at the end of June 2010.

    It took me a while to find one, so I thought I'd share that Fat Tire Farm in Portland, Oregon has three left - after the one I bought Friday. Ask for Tim, (503) 222-FARM.

    I have nothing to do with this store. I'm just helping anyone who might be trying to find one of these bikes. It's an awesome bike!

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