Grom DH Bikes - which is better - Kona vs Specialized?

rick79

Likes Dirt
Hey fellas,

My son currently runs a 09 Kona Stinky 2-4 frame

its a great frame geo wise i feel, but it is very heavy for his 25kg light weight...and thus have had and continue to have issues with the rear Fox rp2 giving a nice plush active suspesion feel.

A Specialized Big Hir Grom frame has come up, and im wondering is this frame any better, lighter, and the linkage system lending itself anymore to livening the rear end up for a featherweight?
 

morticus

Likes Dirt
I think i can comment on the BigHit Grom, as its a smaller version of the BigHit SPEC. I rode the absolute crap out of mine, never serviced it and just fixed parts as they broke, including a set of single crown forks, and 2 sets of Dual crown. For what the bike is, it was quite heavy, looking at around 19.5kg. The suspension wasn't very lively at all, and suffered really bad from pedal bob. Not sure if it would be a massive difference on the smaller frame, but a super light spring could help with the suspension, especially with the little one being 25kg. The frame will however take whatever he/she could throw at it and still ask for more. I saw there was a mini DH bike made by commencal, not sure how much you want to spend? Im almost certain that the suspension design on the stinky would be much plusher and be more friendly for someone getting into the sport.
 

morticus

Likes Dirt
Sorry didnt realize they kept updating the bighit grom along with the bigger model. What year are you talking for the frame?
 

rick79

Likes Dirt
Sorry didnt realize they kept updating the bighit grom along with the bigger model. What year are you talking for the frame?
yeah hes riding a 09 Stinky frame, and the Grom frame that i have seen is arounf 07 i think.
 

morticus

Likes Dirt
As i said, if possible have a look at the bike Shredden just put up. Not sure how much you want to spend though, or how quickly your son will grow out of it. I doubt you would have too much drama selling it on. As for the Stinky vs Bighit, as much of a Specialized fan i am, id be saying try a different spring weight on the Stinky, or change the shock out for something more suitable. My 2c anyways...
 

donthucktoflat

Eats Squid
As I said before in the stinks 2-4 thread go n invest in a fox vanilla shock (should be cheap as for an old non piggyback vanilla r in a short eeye to eye) and whack in a 100-150lb spring
 

skwiz05

Likes Bikes and Dirt
I still own a Big Hit SPEC in large. Im 100kgs, and ride it hard for light DH/freeride type stuff.
A lot of older bikes , stock, may not be as good as newer bikes, until you change a few parts.
Nothing wrong with a single pivot, with the right shock (im using DHX5 AIR) and a Totem fork, the bike rides nearly as well as anything new. And mine isnt that heavy. In fact its way lighter than my bighit FSR....

So, for a small person/kid, its probably the ideal frame to start with cheap, if you can do a few mods, might be a pretty nice ride....
 
difficult setup

I have read a few similar posts to this of late, and although I think that suspension should be avoided as much as possible until a rider has developed sound bike handling skills, I dont know what your groms skills are like so I will answer as if they are advanced.

With a rider this light I honestly think that and I think it would be worth analyzing the groms actual riding more, there is a very real chance that the riders arms and legs are not strong enough to make the suspension work properly, add this to the fact that the balance of sprung to unsprung weight is not going to be anywhere near that of a 70kg rider meaning that it would be physically impossible for the suspension to work as effectively to smooth the bumps out like it would for the heavier rider. Ever felt the difference in ride quality between a range rover and a suzuki sierra? this is the difference I'm talking about.

Further more have you been able to achieve an effective amount of suspension sag? without sag there is no way you will have any chance of getting his suspension active.

Just the stiction of the seals on the shocks is probably going to provide more than enough damping action for the combination of super low spring rates and the out of proportion sprung V unsprung weight that you will have going on here.

If I was trying to setup this bike myself, I would buy a cheap coil shock, find a spring that gives a good amount of sag or have one made, and then pull the damper apart remove all its internals and put it back together like a lubricated air can on an air shock (minus the air charge) and start from there.
 
air shocks

also, a simple air sprung shock will naturally have more stiction from the seals than a coil shock due to the air pressure acting on the seals (might not make much difference for heavy riders put in this instance there is a good chance it will).
 

Gravity Addict

Likes Dirt
g'day i know he's a bit older
but my little bro is riding a small reign sx 2011
that we got for new, cheap to
he weights only about 40-50 kilos
it's a great bike for him he dosen't utilise all the suspension but he seems to be growing into it and has improved a ton on it
hope that provides some assistance
probably dosen't though
sorry
 

T-Rex

Template denier
Back in the day T-Rex Junior had a Bigh Hit Grom. That was about 6 years ago, and I believe it's still doing the rounds, pretty much built like a tank and weighs about the same.

In the end that thing was like grandma's axe, the only original parts left were the frame and seat post. We sold it second hand for considerably more that we paid for it new, a reflection of the parts that were attached to it.

In hindsight, this was probaly not a good use of money. It's really hard to get the suspension working properly when the rider weighs 5kg more than the bike, that's just the reality of physics.

Don't over-think it, just get him to ride the bike heaps, keep feeding him and wait until he grows into a 26". If he's a strong rider there's nothing wrong with putting him onto a bike that's too big, he'll grow into it and you don't need to worry about him breaking it. We know a couple of litte guys in our club, 10 -11 years old, already flogging 26" bikes and hucking off everything in sight.
 
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