Big Hit Grom Build- Mtbr.com
Results 1 to 49 of 49
  1. #1
    mtbr member
    Reputation:
    Join Date
    Apr 2013
    Posts
    59

    Big Hit Grom Build

    I got my two boys season passes to ride downhill at Winter Park this summer. The boys are 10 and 11 y/o. They have been riding 24" hardtail bikes. The youngest on a dirt jumper we built from an old Performance Bike 24" mountain bike and the older and a 24" Rocky Mountain Reaper. We were having teething issues with the Reaper dropping chains like crazy so I decided to let the boys rent bikes.

    Big mistake. Coming off hardtails, the youngest got to ride a 24" Commencal Supreme and the oldest rode a Specialized Status Grom. Only took a run for them to figure out full suspension was the way to go. I almost ended the day walking out of there purchasing a used Commencal bike.

    Instead I started the search for some suitable frames to build some bikes specifically for downhill. If any of you have searched for 24" downhill bikes, you know how rare they are. Just so happened there was bike number 1 on eBay that weekend, an old Specialized Big Hit Grom frame. The older 04-06 version. It was frame only, which works for me. I usually end up throwing everything away.

    After a bit of a bidding war I won it. Of course I realized that if I didn't win it, it would be a year before I saw another one.



    The bike looked beat, the seller had no info and the shipping charges sucked. But, here it is in all it's glory. Cost about $200 with shipping. What looked like dents and bends where just shadows and scrapes. The bike had been through hell but it was straight and dent free.

    Of course all you have to do is pick one of these babies up and you'll quickly realize that this thing is indestructible. It is basically a full blown adults frame sized for a kid. They may no changes in tubing sizes or gussets to account for the 100 pound reduction in rider weight. It's a tank.

    I beat the bearings out of the frame and sent it out for powder coating. I went back and forth on colors forever and settled on a textured black finish. I't kinda a cross between my Giant Reign and a Harley Buell engine finish.



    It came out excellent. The finish is going to be as durable as the frame. I went ahead and installed a set of new Enduro pivot bearings in the swingarm. My neighbor donated a brand new Fox Float for the build. It is the stock 7.5 x 2" size. I was hoping to try a slightly longer shock but the price was sure good. I order some new bushings to match the frame and found a Chinese company on ebay selling "bearing axles" which make the perfect shock bolts.



    I dumped the old headset cups and installed an FSA Orbit MX headset. Overall the stack height is pretty tall. I went to install the fork (an old Pike from my Reaper build) and it was too short. I had maybe 1/2' of steerer sticking out. So now the hunt for a new fork begins.

    Finding a new fork was a challenge. Not only because of the spec I needed but the budget as well. I plan on using the wheels off my older son's Reaper. They have a 20mm front hub. So basically I was looking for a 120-150mm fork with a 20mm axle and a 7-1/2" long 1-1/8" steerer. I quickly learned that these aren't very commom.... in my budget. Oh, and did I mention it needed to be an air fork as well. I quickly discovered that almost all forks in this travel range use tapered steerers. Almost everyone uses a 15mm axle now and new forks cost a fortune.

    I finally found the perfect fork and it's being delivered this week. I scored a Rock Shox Argyle RCT off PinkBike. More money that I wanted..by far but it is a solo air, 140mm fork with a 20mm axle and a long straight 1-1/8" steerer. And it's probably over a pound lighter than the old Pike I was going to use.



    The fork was just rebuilt and the travel was set to 100mm. I'll pull some of the spacers out of it and set it around 120-140mm depending how the bike sits.

    Chuck

  2. #2
    mtbr member
    Reputation:
    Join Date
    Jun 2009
    Posts
    657
    Sweet! Keep posting pics once you have it built up!


    Sent from my iPhone using Tapatalk

  3. #3
    mtbr member
    Reputation:
    Join Date
    Jun 2006
    Posts
    8,720
    Very cool!
    I just sold ours last week as my son has moved to 26". You got me thinking I should've asked more for it.
    Sinister Bikes
    Wraith Bicycles
    Sunday River Mtn Bike Park
    NEMBA
    Wachusett Brewing Co.

  4. #4
    mtbr member
    Reputation:
    Join Date
    Apr 2013
    Posts
    59
    I went ahead and put the fork and wheels on the bike yesterday. I am really pleased on how its coming out and to say my 10y/o is thrilled is an understatement.





    We went ahead and used one of our old Speedline 155mm BMX cranks. This was combined with a Straitline guide and a 36t E13 chainring. I decided to go with the Straitline guide since it had no moving parts and would hopefully be low maintenance. Jason likes clips still so we moved over his Time platform pedals.



    I further gutted his brothers dirt jumper for the bars and stem. The stem is a 40mm and the bars are some used FSA carbons I got off of eBay. Everyone is going wide on their bars so when someone sells a set that was cut a little narrow they go cheap.



    The frame specs from Specialized mentioned "offset rear for 0 dish rear wheel". This basically meant they built the swingarm offset to the right so the spokes all had the same angle from the hub to the rim. In other words, if you put on a standard rear wheel it looks like this:



    Right now the bike is at a wheel builder buddy to have the rear re-dished. Stay tuned for brakes and shifters...

    Chuck
    Last edited by chuckactor; 08-07-2015 at 02:07 PM.

  5. #5
    mtbr member
    Reputation:
    Join Date
    Aug 2015
    Posts
    6
    What wheels and tires are you using? I got the purple version from 2009 I think. I may end up powder coating it as well. Thanks for the details.

  6. #6
    mtbr member
    Reputation:
    Join Date
    Apr 2013
    Posts
    59
    The wheels consists of a Novatech rear hub. I think its a D522. The front hub is either a WTB or Formula. Not really sure as I bought a used 29" front wheel (WTB) with a 20mm front hub and threw away everything but the hub. Both are 32H and laced with double butted spokes to a set of Alex ACE20 rims. I bought the rims from an eBay seller last year. I can try to dig up the sellers name if you like. The wheels are pretty light and have proven to be pretty durable. They are a bit narrow though as I assume they are intended to be lightweight X-country rims. For tires we have been running 2.25" Schwalbe table tops at the bike park and a pair of 2.35" Intense DH tires for the downhill. Wish I would have bought two pairs of the Intenses when I found them.... The only DH tires you can find now are 2.5" which is getting pretty big for a little kid.

  7. #7
    mtbr member
    Reputation:
    Join Date
    Aug 2015
    Posts
    6
    I am trying to source Kendal Kinetics tires 24 x 2.35. Should be fairly light. Looks like I have a powder coat lined up but need to get it bead blasted first. Did you use someone on the North Shore to have it bead blasted? Thanks for the advice. I am still a ways away from sourcing wheels

  8. #8
    mtbr member
    Reputation:
    Join Date
    Apr 2013
    Posts
    59
    Finished the bike up last Friday night and took it to WinterPark. I signed the boys up for a Freeride camp and they lucked out and spend the day with an instructor all to themselves.

    The bike was finished off with a Sram X9 9-speed short cage derailleur and matching shifter. The wheelset already has an XTR 12-34 cassette. For brakes we transferred over a set of Hayes Strokers with 160/180 rotors.

    Overall the first day went great. The only thing I need to do was some air adjustments in the fork and shock.





    No action shots from Downhill but my wife did capture the boys playing around at Valmont bike park in Boulder.



    Now to try to finish my 11 y/o's Morewood for Steamboat this weekend....

    Chuck
    Last edited by chuckactor; 08-13-2015 at 01:02 PM.

  9. #9
    mtbr member
    Reputation: tomfish's Avatar
    Join Date
    Aug 2010
    Posts
    146
    so killer!!

  10. #10
    mtbr member
    Reputation:
    Join Date
    Apr 2013
    Posts
    59
    The bike turned out awesome and he loves it. A bit on the heavy side at just under 31 pounds with pedals etc. but it doesn't appear to slow him down.

    Chuck

  11. #11
    mtbr member
    Reputation: Chad_M's Avatar
    Join Date
    Jul 2013
    Posts
    505
    Impressive!

  12. #12
    mtbr member
    Reputation:
    Join Date
    Jun 2006
    Posts
    8,720
    Love that last pic. Awesome!
    Sinister Bikes
    Wraith Bicycles
    Sunday River Mtn Bike Park
    NEMBA
    Wachusett Brewing Co.

  13. #13
    mtbr member
    Reputation:
    Join Date
    Aug 2015
    Posts
    6

    Thanks for the inspiration!

    Thanks for all the advice on doing a similar project for my seven year old. He is still quite a little guy and the bike looks big for him but we took it to Whistler and it was great. I am in the process of building new wheels for him as I think it is still around 33 pounds. The current wheels are quite heavy so I should be able to do much better. Like I say he is short but I was amazed at how fast he got comfortable jumping on it. No pictures of him but I did shoot some Go Pro footage:


    https://www.youtube.com/watch?v=qRivx97Dc_g
    Attached Thumbnails Attached Thumbnails Big Hit Grom Build-bighit-grom.jpg  


  14. #14
    mtbr member
    Reputation:
    Join Date
    Apr 2013
    Posts
    59
    Wow! Awesome build. He looks great on the bike. Best part, he'll be riding it for the next few seasons. My son (10) took to his great. I think we are at 31.5lbs. The frame weighs alot. Thanks for sahring.

    Chuck

  15. #15
    mtbr member
    Reputation:
    Join Date
    Sep 2011
    Posts
    118
    I picked up one of these Gromhits for my 7 year old as well, same 2009 model as srichard. I've been messing around with it, and I thought I'd share a tip, and ask a question....

    First, I just couldn't get the stock Z1 soft enough for my 55 lbs son. Super quick fix was to open up the right fork leg, and pull out the spring. Now it is an air shock and seems to be working very well for a light rider. Here is a YouTube video showing how:

    www.youtube.com/watch?v=zUzAuEeQ3sk

    Question.... the stock 165 cranks are way too long for my son. I would like to swap out to something shorter, but will need to switch to a square BB (stock is ISIS). Does anyone know the right spindle length on the 2009 Gromhit? 68 x ???

    Thanks

  16. #16
    mtbr member
    Reputation:
    Join Date
    Apr 2013
    Posts
    59
    With the older model, we are running a 73x122 square bottom bracket. We have a 2mm spacer behind the drive side cup to get the chain guide lined up. Are you sure the newer one runs a 68mm bottom bracket shell? The specs have it listed as a 73mm.

    Specialized Bicycle Components

    Based on the years of BMX racing, I'm guessing a 145mm or 150mm crank would be about right. My son is 10 y/o and runs a 155mm although his BMX 20 and cruisers have 150mm cranks.

    Chuck

  17. #17
    mtbr member
    Reputation:
    Join Date
    Sep 2011
    Posts
    118
    My shop measured the shell as 68, but you are clearly right that Spec lists it as 73. Stupid question... don't most BB's work either way? you just need the little spacer if the shell is 73?

    I measured chain line at 52mm with the stock set up, so I was guessing the longer spindle (like the 122 you used) is probably right. But I also was hoping to try to keep the Q factor as narrow as possible.

    We are running 140mm cranks on his XS Juliana with 24" wheels. I have some spare 152mm 104 bcd cranks that I was going to use on the Juliana when we converted it (probably this winter/spring) to 26" wheels and raised the BB height. But was thinking of just putting the 152 on the Gromhit for the time being. That will also let us ditch the heavy chain guide on the Grom and run a spare N/W ring I have in the parts bin.

  18. #18
    mtbr member
    Reputation:
    Join Date
    Apr 2013
    Posts
    59
    It's likely a 73mm. I had alot of grief trying to use a 68mm bottom bracket in my older son's Rocky Mountain Reaper dirt jumper. The left cup ends up screwing into the bottom bracket shell. If you need to space the BB to the right, you probably don't have enough threads on the left shell to compensate. When I built the older Grom, I seem to remember the chainline with the 73x122 BB was around 50mm.

    You can pickup a Shimano UN54 BB pretty cheap. I opted for the Token but you might need to search for that one. The UN55 is another option but not quite as nice in my opinion.

    With the BMX race bikes I always tried to keep the Q-Factor narrow. For the downhill, they don't notice the difference. Besides, if you go narrow, the chain guide will never line up. This has been my biggest issue building downhill bikes or bikes with chain guides. I went through 3 bottom brackets before I got it right.

    Chuck

  19. #19
    mtbr member
    Reputation:
    Join Date
    Sep 2011
    Posts
    118
    Of course... I just went with the "smaller Q factor = better" without thinking. DH bike isn't going to be pedaled much.

    Realized the spindle depends on the cranks. Looked up the cranks (Prowheel Pioneer Square Taper 152). Their website says a 110.5mm spindle gives a 45mm chainline. Since I'm gunning for about 50mm chainline, I think something in the 120mm range is going to be spot on.

    Thanks for helping me think it through.

  20. #20
    mtbr member
    Reputation:
    Join Date
    Sep 2015
    Posts
    4
    great looking build on the big hit grom, and you kid looks great jumping it. Don't think trying to go extra long on the rear shock is worth worrying about.
    The 2.5 inch tires are not too much. My son used Specialized chunders at 2.5 and they work fine. Tried some other tires also found online, a "2.6" was much narrower than the 2.5 chunders.

    As of last weekend, I think my 11 y/o is moving up from his Big Hit Grom 24" Wheel set up into a full sized DH mountain bike.

    It's a long story, but I actually have 2 essentially identical bikes running around 37 lbs with the stock wheels that I'll likely be selling sometime soon. Ironically on the weight factor, I think it's way overrated for this dh bike as he's done great on it with lots of miles at Angel Fire and the weight hasn't been a factor for him, nor a really good smaller sized motocross 10 y/o kid that borrowed the back up a few times.

    In addition, I have another bare frame that I have most parts to build up a 3rd bike.

    However, I'd like to get some specifics on the "nuts/bolts" on your build:

    a) How much did your powder coating run?
    b) What was the specifics on the frame bearings you bought from China?
    (Do you have the link to the seller?)
    c) What/where did you get the swingarm bolt from? (I lost the smaller bolt on
    a frame).
    d) You mention Winter Park, did your get your wheels built up somewhere in Denver Area? And what type of expense on making custom wheels?

    May need other info in future, ie. I don't even know what a Q-Factor is....

    Appreciate any info you can provide.

    Thanks.

  21. #21
    mtbr member
    Reputation:
    Join Date
    Apr 2013
    Posts
    59
    You should have no trouble at all selling the Big Hit Groms. The bottom line is that there are very few bikes out there for the little kids.

    My 11 y/o is riding a full size 26" downhill bike. He is not that tall but is not having any trouble at all. It's actually easier and cheaper putting together a bigger bike. Everyone wants to go 27.5' wheels so the 26" stuff is cheap. I bought a set of 26" DH wheels with tires for under $100. The bike I built for the 11 y/o is a small Morewood Shova LT frame and a RockShox Totem solo air fork. The rear shock is a Vanilla R with a 250lb spring. Usual SRAM X9-9spd, Formula The One brakes and a SRAM 165mm Descendant crankset.



    I can't explain the funny look on his face. You get those when you ask them to hold still for a picture....

    The powder coating was $100 for the BHG including the sand blasting and masking. The bearings I used were Enduros 6201's from bikeparts.com. They were $4.50 each. You need to make a press out of some threaded rod, washers and a socket to get them back in the frame. Brut force with a hammer to get them out.... I had the swing arm bolts and spacers with my frame. The bolts are just regular metric allens. Are you referring to the shock bolts? I got those from China.

    M6 8 29 33 45 50 56 70 78mm Bike Bicycle Shock Absorbers Lock Bolts Screw Nut | eBay

    I bought (2) M6x47mm bolts.

    I just finished building up another set of 24" wheels. A local friend build the first set and I just built the second set. I found it best to hunt Craigslist for wheels to steal the hubs out of. Any decent 32H hub will do. You can get Deore hubs off Niagra Cycles for about $55. The rims are a bit narrow but have been super strong. I use Alex ACE20s. They don't make them anymore but there is a guy in California who has them for $46/pair. The spokes and nipples came from Danscomp, the BMX place. They have Sapin double butted the cheapest. I think it was $53 shipped for black spokes and alloy nipples. Go silver with brass nipples and they are only $0.40/ea.

    Q-Factor is the distance between the two pedals on the crank. Basically if you look down on them. Kinda a measure of how far your feet are going to be apart. Alot of people tr yto narrow the width of the crank as much as they can. For downhill, you'll find out your struggling just to get chain guides to line up and keep the crank arms from hitting the swing arm.

    If you don't build up the third frame, I might be very interested in it. There is a chance I have two cracks in my swing arm. Could be a crack in the powder coat.... that's what I'm hoping. I see a fine dust line near a couple of the braces. I can weld it and re-powder coat but I'd much rather find another frame or swing arm as a backup.

    Chuck

  22. #22
    mtbr member
    Reputation:
    Join Date
    Sep 2015
    Posts
    4
    thanks for info, you can send me a pm about a possible frame

  23. #23
    mtbr member
    Reputation:
    Join Date
    Aug 2015
    Posts
    6

    Cranks

    Again thanks for all the advice on this thread. I finished his bike off with the Stan's No-tubes crest rims on a hope hub and the Kenda Kinetic tire. Got the bike down to 30lbs which I believe is the same as the Transition ripcord. The only regret I have is not getting the shorter cranks. I was told the Canfield ones are great (although a bit on the expensive side)

    Canfield Brothers Cranks - Shortest DH cranks avialble

    May upgrade next summer as I hope he won't mind doing some climbing on this bike as well as riding the park. For now the 165mm cranks aren't holding him back. I have heard people say that the Ripcord is a better investment because of the shorter chain stays but so far this doesn't seem to be holding my 7 year old back.

    https://www.youtube.com/watch?v=gaC3toVD1Zk

    My only problem is that the bike is too good and I am not going to be bale to keep up with him for much longer!
    Last edited by srickard; 10-26-2015 at 08:57 AM.

  24. #24
    mtbr member
    Reputation:
    Join Date
    Apr 2013
    Posts
    59
    Nothing to do with the build but a cool pic of Jason on the BHG we got last night at Valmont Bike park.



    Trying to get in riding before the snow starts.

  25. #25
    mtbr member
    Reputation:
    Join Date
    Aug 2015
    Posts
    6
    Wow that is an awesome picture. Hope you blow that up and put it on his wall!

  26. #26
    Third Degree Hater-Fu
    Reputation: bizutch's Avatar
    Join Date
    Aug 2004
    Posts
    563
    Nice to see someone is talking about this still. The thread on another forum died off and I got a complete stock Big Hit Grom a few months back for $350. It had been sitting in a guys garage for years. Fantastic shape, but couldn't even get my 11 yr old daughter to ride it. Has the stock shock ( something RF tuned) and it is terrible. So I found a Fox RL air shock that I'm waiting on to show up.

    Suspension Experts said the shock won't be valved for the bike specifically, but it will be worlds better than the stock. The MZ Comp fork is a boat anchor as well as the wheels.

    Come to find out after prodding miss poo poo face about why she didn't like it, she couldn't reach the mechanical Tektro disc lever. Dialed it in but power was terrible for her little hand. Found a guy giving up a nearly new set of Hayes Stroker Trails and the reach adjust was the key.

    Any suggestions for what the best small disc brake for little hands is?
    Only bad thing on it is he somehow put a set of Bontrager 170mm XC cranks and triple ring up front on it.

    More suggestion requests:
    1. Pedals that don't make a kid pushing a bike bleed to death?
    2. 100mm+ air fork, standard QR dropout (1 1/8" steerer)
    3. Cheap way to do light 24" wheels? Having someone BUILD them really jacks up the price
    4. Crank/ BB combo - shop said they found a set of SR Suntour square taper 152mm cranks for $40 from BTI or Hawley. Thoughts?

    I bought a Maxxis High Roller for the front and ironically the Specialized "Roller" DH from the front is on back and in great shape.
    I am not a "Role Model"

  27. #27
    mtbr member
    Reputation:
    Join Date
    Apr 2013
    Posts
    59
    Congrats on your build. The bike is a tank but it's a fun platform to build on and your kid will love it. I hate to suggest it but....have you thought of powdercoating it a color she really likes? My kids really enjoy picking out a color to make the bike "theirs". My 11 y/o son loves his metallic dark purple dirt jumper. He especially likes the wheels we built with purple nipples and purple ODI grip clamps.

    As far as pedals, look for some plastic dirt jumper pedals. They grip good but won't fillet your shins like a set of metal spikes. My son has a set of Dartmoor pedals and they work well. Candy Pro | D A R T M O O R

    Forks are the big issue. The head tube is kinda long so be careful when shopping for a used fork that they didn't chop the steerer to short. We ended up with an Argyle RCT (140mm). They are out of business but a Marzocchi 55 air fork would work real well if you can find one. Also an old Pike.

    Building your own wheels is fun. Hunt craigslist for a set of 26" disk wheels. Or look for hubs. Most of the time its cheaper to buy someones old 26" wheels and throw everything away except the hubs. I found a guy with Alex Ace 20 rims in stock (32h). They only cost $53/pr shipped. For spokes, I buy them from Dans Comp, the BMX place. They'll cut the spokes to size. I used double butted Sapins with aluminum nipples. Just remember to offset the rear 6mm to the left.

    The 152mm SR crank is OK. Best bet is a single speed BMX crank (Sinz etc) on a 122x73 BB. You can then use any length you want. Check ebay or facebook BMX classified pages.

    As far as brakes, we ran the Strokers but they are a bear to bleed and the edjuster for the lever travel kept moving. My sons bike now has a set of used Avid Elixir 5 brakes. You can find nice used sets for 70-80 bucks.

    Chuck

  28. #28
    mtbr member
    Reputation:
    Join Date
    Feb 2008
    Posts
    661
    Quote Originally Posted by bizutch View Post
    2. 100mm+ air fork, standard QR dropout (1 1/8" steerer)
    Godspeed. Straight 1-1/8 steerer, single crown, 9mm QR dropout forks are basically unobtanium at this point.

  29. #29
    mtbr member
    Reputation:
    Join Date
    Apr 2013
    Posts
    59
    Going to have to go used. Maybe a Fox F-series or a Rockshox Tora or Reba. I had to bite the bullet and buy a Argyle RCT. I need a 20mm axle and 140mm of travel. If your going to build wheels then I would not use the 9mm QR. I would go to a 15mm or 20mm front axle. Lotsa Foxes with 15mm axles. Straight steerer is the hard one . Check Pinkbike.com

  30. #30
    mtbr member
    Reputation:
    Join Date
    Sep 2011
    Posts
    118
    I'll might have a 24" wheel set to unload if you can wait till spring, when the little guy gets 26" wheels on his XS Juliana. Built the wheels up with light novatec hubs and the ace20 rims. PM me if interested.

    I also have a Gromhit and wouldn't mind swapping out the too long cranks. But stock BB is some crazy octalink stuff. chuckactor you pretty sure 122 is the right length for the BB? I was thinking something a little shorter.

    For brakes. Gotta love the shimano stuff for little hands and power. But cost is a thing. We are running the slx on the Juliana and they work amazing.

  31. #31
    mtbr member
    Reputation:
    Join Date
    Apr 2013
    Posts
    59
    If you run a single speed BMX crank then you need a 73 x 122 or 123 BB. It will give you a perfect chainline (I think around 50mm if my memory serves me...). I tried 115mm and 118mm and they are to short. A Shimano UN54 or 55 works. The 55 has the aluminum left cup, the 54 is plastic. I used an Origin 8 but they are a bit harder to find.

    If you are going to use a chainguide then the chainline is critical. I ran the guide with the 122.5mm BB and it lined up perfect with a thin spacer behind the right cup.

  32. #32
    mtbr member
    Reputation:
    Join Date
    Sep 2011
    Posts
    118
    Thanks. And to confirm your memory, I measured chainline right at 50-51mm to use the guide.

    Now I just have to figure out how to get the drive side octalink cup off!

  33. #33
    Dr. Pepper drinker
    Reputation: catch22's Avatar
    Join Date
    Apr 2004
    Posts
    1,634
    Quote Originally Posted by RMCDan View Post
    Godspeed. Straight 1-1/8 steerer, single crown, 9mm QR dropout forks are basically unobtanium at this point.
    There are a few more out there than you would think but probably a special order item for most shops. Most options are 100mm but Rockshox still makes a Reba RL in 120mm and Manitou has the Minute Comp in 120mm. I think Magura is making the new TS6 and TS8 forks with a 120mm straight steerer as well. I don't know of anything longer than 120mm, if I was looking for 140 I'd be looking at used markets for a Reba or Revelation.
    Sipping the Knolly Whisquillappa

  34. #34
    Third Degree Hater-Fu
    Reputation: bizutch's Avatar
    Join Date
    Aug 2004
    Posts
    563
    Quote Originally Posted by Surfpoodi View Post
    I'll might have a 24" wheel set to unload if you can wait till spring, when the little guy gets 26" wheels on his XS Juliana. Built the wheels up with light novatec hubs and the ace20 rims. PM me if interested.

    I also have a Gromhit and wouldn't mind swapping out the too long cranks. But stock BB is some crazy octalink stuff. chuckactor you pretty sure 122 is the right length for the BB? I was thinking something a little shorter.

    For brakes. Gotta love the shimano stuff for little hands and power. But cost is a thing. We are running the slx on the Juliana and they work amazing.
    Email me when you're ready to drop that wheelset please. [email protected] . Thanks.
    I am not a "Role Model"

  35. #35
    Third Degree Hater-Fu
    Reputation: bizutch's Avatar
    Join Date
    Aug 2004
    Posts
    563
    Is the BB mount for the BigHitGrom ICGS or ICGS 05? This one had triple chain rings on it and 170s (why I don't know).

  36. #36
    mtbr member
    Reputation:
    Join Date
    Apr 2013
    Posts
    59
    It is ISCG or sometimes referred to as ISCG-OLD.

    Chuck

  37. #37
    Third Degree Hater-Fu
    Reputation: bizutch's Avatar
    Join Date
    Aug 2004
    Posts
    563
    Quote Originally Posted by chuckactor View Post
    It is ISCG or sometimes referred to as ISCG-OLD.

    Chuck
    Thanks. THought it would be easy to find one of those this week, but I think the answer might be a Deore 10 speed OEM groupo in the local shop. Clutch deraillier, chain and cassette for $100. Cheaper than a bash alone.

    Oh, and it's official. I weighed it and we're between 37-38lbs.
    The rear Fox RL shock I picked up online was terrible. Something inside the damper (checked the air can) is rattling. So $75 internet rip-off. Bah!
    I am not a "Role Model"

  38. #38
    mtbr member
    Reputation:
    Join Date
    Apr 2013
    Posts
    59
    I just went to see where we are at weight wise... we are just shy of 31 pounds with pedals.

    Chuck

  39. #39
    Third Degree Hater-Fu
    Reputation: bizutch's Avatar
    Join Date
    Aug 2004
    Posts
    563
    My head is gonna explode. Suspension Experts and I must have miscommunicated. They gave me a 7.75" Fox Aid CTD. It's all of about a millimeter too long. Snot.

    Managed to sell the Hayes Stroker Trails (once the reach is run in all the way, their too long for the girls to use one/two finger pull. Lucked out and found a set of OEM Deore's brand new and they're perfect. Billy Goat Bikes has a TON of OEM stuff they're not advertising from build kits if anyone needs something local.
    I am not a "Role Model"

  40. #40
    mtbr member
    Reputation:
    Join Date
    Apr 2013
    Posts
    59
    Stock shock is a 7.5 x 2.0. I have heard that a 7.75 shock will fit. Is the swingarm hitting the downtube because the shock is too long?

    There might be a fix if you have a little clearance between either the top shock eye and the frame or the bottom shock eye and the swingarm.

    They make eccentric shock bushings that allow you to lengthen or shorten the shock mounting about 2-3 millimeters on both ends. I use them on my other son's DH bike. It allows me to use a longer travel shock but effectively shorten it about 3/8" to slacken the head angle a bit. You can run them on either end or both ends.

    Offset Shock Bushings Mounting Hardware Mount Kit All Frames Proshox | eBay

  41. #41
    Third Degree Hater-Fu
    Reputation: bizutch's Avatar
    Join Date
    Aug 2004
    Posts
    563
    Quote Originally Posted by chuckactor View Post
    Stock shock is a 7.5 x 2.0. I have heard that a 7.75 shock will fit. Is the swingarm hitting the downtube because the shock is too long?

    There might be a fix if you have a little clearance between either the top shock eye and the frame or the bottom shock eye and the swingarm.

    They make eccentric shock bushings that allow you to lengthen or shorten the shock mounting about 2-3 millimeters on both ends. I use them on my other son's DH bike. It allows me to use a longer travel shock but effectively shorten it about 3/8" to slacken the head angle a bit. You can run them on either end or both ends.

    Offset Shock Bushings Mounting Hardware Mount Kit All Frames Proshox | eBay
    I took it back and got my money back luckily. The 7.875" collided with the rear seattube...but oh so barely. I'm seeing several Fox CTD shocks on Pinkbike in that length and a 2014 X Fusion, but don't trust that brand just yet.

    Problem with the CTD's for sale is they are all remote activated and trying to avoid one more contraption on the bars to break.
    Last edited by bizutch; 02-03-2016 at 03:52 PM.

  42. #42
    mtbr member
    Reputation:
    Join Date
    Jun 2006
    Posts
    8,720
    I was able to mount a 7.625" Fox RL shock on my son's BH w/o any issues, in case that helps.
    Sinister Bikes
    Wraith Bicycles
    Sunday River Mtn Bike Park
    NEMBA
    Wachusett Brewing Co.

  43. #43
    mtbr member
    Reputation:
    Join Date
    Apr 2013
    Posts
    59
    Reply, I think the offset bushing might have worked in this case. Either way, take a look at Mountain bike news, photos, videos and events - Pinkbike in the buy/sell section. There are some nice shock options in the 7.50 length. A DHX Air and a DHX Coil.

    Chuck

  44. #44
    Third Degree Hater-Fu
    Reputation: bizutch's Avatar
    Join Date
    Aug 2004
    Posts
    563
    Saw those. Wouldn't think the air can would clear the top tube. Plus, I'm guessing the damping curve is not friendly to lightweight riders?

  45. #45
    mtbr member
    Reputation: oldranger's Avatar
    Join Date
    Apr 2011
    Posts
    162
    I know this is a late response for you Butch (since you've got brakes covered) but the M785 XT stuff is getting cheaper now. Those brakes have simple adjustability for reach and work great for small hands. That - and they are strong enough to keep for the next bike you build when the kids' speeds starting justifying a full blown DH bike.

    They have handled a full year of work on Ben's bike. The typical big crashes, muddy conditions, etc. Shimano brake lines are VERY durable.

  46. #46
    mtbr member
    Reputation:
    Join Date
    Apr 2013
    Posts
    59
    I know this isn't the right forum for this but I am selling the Big Hit Grom I built up. My son has moved on to a Specialized Demo 8. If you know anyone who is interested, let me know.

    Thanks!
    Chuck

  47. #47
    Third Degree Hater-Fu
    Reputation: bizutch's Avatar
    Join Date
    Aug 2004
    Posts
    563
    Quote Originally Posted by chuckactor View Post
    I know this isn't the right forum for this but I am selling the Big Hit Grom I built up. My son has moved on to a Specialized Demo 8. If you know anyone who is interested, let me know.

    Thanks!
    Chuck
    It's definitely a good place. How much, pics, link to the ad, etc?
    I am not a "Role Model"

  48. #48
    mtbr member
    Reputation:
    Join Date
    Apr 2013
    Posts
    59

  49. #49
    mtbr member
    Reputation:
    Join Date
    Apr 2013
    Posts
    59
    Season is done for us. My youngest has become attached to his XS Demo 8. I'm going to put the BGH up on eBay soon. Bike is in great shape. I upgrade the brakes to some Avid Elixir 5's with the super cool HSX rotors (180mm). This bike has been bullet proof. Comes with spare rotors, derailleur hanger. Spare Avid Elixir brakes. Might have a cassette and some brake pads. Asking $1,000. PM me for bikes and a completed build list.

    Chuck

Similar Threads

  1. Camber Grom
    By TwoTone in forum Families and Riding with Kids
    Replies: 5
    Last Post: 11-25-2014, 08:52 PM
  2. Specialized Camber Grom
    By Defender90 in forum Families and Riding with Kids
    Replies: 9
    Last Post: 09-25-2014, 04:28 PM
  3. What exactly is a grom?
    By dv8xin in forum Beginner's Corner
    Replies: 4
    Last Post: 03-19-2013, 04:23 PM
  4. Specialized Big Hit Grom SPEC
    By posey24 in forum Beginner's Corner
    Replies: 17
    Last Post: 06-20-2011, 10:57 PM
  5. Specialized Big Hit Grom SPEC
    By posey24 in forum Specialized
    Replies: 0
    Last Post: 06-20-2011, 01:11 AM

Members who have read this thread: 1

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

THE SITE

ABOUT MTBR

VISIT US AT

© Copyright 2020 VerticalScope Inc. All rights reserved.