Kids MTBs - jump from 20" to 24" ?

takai

Eats Squid
Ok, my eldest seems to be going through bikes like they are going out of fashion. We are planning on getting him a new bike soon as the single speed he is using currently has him quite limited on both hills and descents (it was a free BYK so wasnt going to say no)

He is quite tall and lanky and so has rapidly grown out of the BYK E250 that he started with and then powered past the E350 in a year, and is now on an E450 (20") but at only 6 years old is rapidly approaching 125cm which seems to be the crossover point for 20" to 24" wheels (according to the manufacturers).

Currently tossing up between another 20" bike with gears, like the 20" Relic (https://www.bicyclesonline.com.au/polygon-relic-20-inch-kids-mountain-bike) or a Giant XTC Jr (https://www.giant-bicycles.com/au/xtc-jr-20)
Or getting him a 24" which (hopefully) will last him until he is a lot older, like the XTC SL Jr 24 (https://www.giant-bicycles.com/au/xtc-sl-jr-24) or the Relic Evo (https://www.bicyclesonline.com.au/2020-polygon-relic-evo-24-inch-kids-mountain-bike)

I guess the real question im asking here is where to go in the crossover point. Should we stick with a 20" to develop skills, or just let him learn to handle a much larger bike?
 

ashes_mtb

Has preferences
My 7yr old is that height and still well within the 20" size. He could ride a 24, but not comfortably or with same control.

I'd go a 2nd hand 20", you should be able to get them cheap. Only issue is getting decent tyres, Schwalbe Little Joe's is all I could find and weren't exactly cheap.
 

PJO

in me vL comy
My 6.5 yr old is 126cm and has just transitioned to a 24". He could've stayed on the 20" for another few cm of growth but he wanted to jump on his brothers old bike. His brother who is 14 months older is still on a 24" but it is a slightly bigger frame.
 

takai

Eats Squid
Ok, just measured him and the 'little' guy is 1255mm :eek:

How in hell do they get that tall so quickly?

Thinking that the 24" might be the go, as he can always ride his 20" BYK if needed.
 

silentbutdeadly

has some good things to say
I guess the real question im asking here is where to go in the crossover point. Should we stick with a 20" to develop skills, or just let him learn to handle a much larger bike?
At that height, I'd go with the 24". The Lad has been on a 24" Polygon Relic for three years now. He's getting to the point of starting to grow out of it now but, at ten years old, only just now developing the basic MTB skills.

Given the new version of the Relic Evo can use either 24" or 26" wheels and actually has a decent fork then it makes decent sense for the money. The only downside is the front derailleur and (I'll wager) pretty ordinary wheels.

The lads original Polygon 24" wheels were so flexy that he bounced and wobbled all over the joint on a bumpy firetrail. So I had a set made using Spank rims on convertible Novatec hubs...added some nice fat Holy Roller tyres and he's had much more control.
 

flamin'trek

Likes Bikes and Dirt
My nephew is 7 and the 24” was too big for off road riding when he first got it in December, he could handle it on road - just, but didn’t have the control needed for off road. My 7yo is still on 20” and will be for a bit longer until his confidence builds some more. Again, just fits the 24” but it’s too big to ride comfortably. They are both the same height.

It comes down to the rider and he riding you do, but I’d stick with smaller for off road.
 

blacksp20

Likes Bikes and Dirt
FWIW, both my kids jumped from 20” to XS 26” at 7yo. So much more on offer with good light parts.
My 8yo is doing the same right now. Coming from a Scott Scale Jr 20 plus to an XS Giant something 26”. He is just over 140cm and is pretty much at minimum standover.
 

boyracer

Likes Dirt
This ^^^
You can get a seat pole 22.2 for BYK for 10-15 bucks to get the last few months out of it.
My 3 went through various BYK SS to an alloy 20 inch GT stomper 1 x 7 speed ( thanks Moorey ) and are moving straight to sweet XC weight 26ers as needed.
 

Jim Junkie

Used to sell drugs, now he just takes them
At that height, I'd go with the 24". The Lad has been on a 24" Polygon Relic for three years now. He's getting to the point of starting to grow out of it now but, at ten years old, only just now developing the basic MTB skills.

Given the new version of the Relic Evo can use either 24" or 26" wheels and actually has a decent fork then it makes decent sense for the money. The only downside is the front derailleur and (I'll wager) pretty ordinary wheels.

The lads original Polygon 24" wheels were so flexy that he bounced and wobbled all over the joint on a bumpy firetrail. So I had a set made using Spank rims on convertible Novatec hubs...added some nice fat Holy Roller tyres and he's had much more control.
What are your thoughts on the relic? My oldest is growing out of his 16 and has a keen interest in mtb, so I'm keen to get him something decent. His height puts him right on the lower limit for the 20" (117cm).
It seems to me the utility of front forks on a 20" is questionable? I was looking at something like a Nukeproof Cub Scout, it's lighter with slightly better kit and hydro brakes, but for 3 times the price I'm not sold on the value vs the polygon.

As far as 26's go, well he's already claimed the Blur downstairs as his, so that's sorted!

Sent from my Pixel 3 XL using Tapatalk
 

Nerf Herder

Wheel size expert
If you want a 24” Merida HT ... and in Sydney or willing to Faff with shipping. You can have it free.

just taking up room in my shed.
 

silentbutdeadly

has some good things to say
What are your thoughts on the relic? My oldest is growing out of his 16 and has a keen interest in mtb, so I'm keen to get him something decent. His height puts him right on the lower limit for the 20" (117cm).
It seems to me the utility of front forks on a 20" is questionable? I was looking at something like a Nukeproof Cub Scout, it's lighter with slightly better kit and hydro brakes, but for 3 times the price I'm not sold on the value vs the polygon.

As far as 26's go, well he's already claimed the Blur downstairs as his, so that's sorted!

Sent from my Pixel 3 XL using Tapatalk
From a value perspective in the sub $500 kids MTB...the Relic in either the 20" or 24" is hard to beat compared to similar stuff from Trek or Specialized. But don't pretend that it's a MTB. Almost all the gear on it won't survive enthusiastic trail belting by a sub-teen.

While we paid mid $300 for the 24", I replaced the wheelset due to its flex (though I could have rebuilt the OE set properly, new Maxxis Holy Roller 2.4 tyres to suit, replaced the daft 3x crankset with a Raleigh 1x set from SJS Cycles, removed the FD and put a decent saddle on the thing too. What I couldn't fix was the fork which quickly failed in terms of rebound control. So we spent another $400 making it something he still likes to ride and could have spent another $150...

Spending that sort of coin on a 20" is insane. But on a 24" that can wear 26" boots...yeah maybe.

In our case, I found a decent 26" Chinesium alloy hardtail frame ages ago at the tip shop and a new Manitou 26" fork from Cycling Deal for $99...and a mate gave me some Mavic wheels. So, when the time comes, we are away...
 

RealizE

Likes Bikes
From a value perspective in the sub $500 kids MTB...the Relic in either the 20" or 24" is hard to beat compared to similar stuff from Trek or Specialized. But don't pretend that it's a MTB. Almost all the gear on it won't survive enthusiastic trail belting by a sub-teen.

While we paid mid $300 for the 24", I replaced the wheelset due to its flex (though I could have rebuilt the OE set properly, new Maxxis Holy Roller 2.4 tyres to suit, replaced the daft 3x crankset with a Raleigh 1x set from SJS Cycles, removed the FD and put a decent saddle on the thing too. What I couldn't fix was the fork which quickly failed in terms of rebound control. So we spent another $400 making it something he still likes to ride and could have spent another $150...

Spending that sort of coin on a 20" is insane. But on a 24" that can wear 26" boots...yeah maybe.

In our case, I found a decent 26" Chinesium alloy hardtail frame ages ago at the tip shop and a new Manitou 26" fork from Cycling Deal for $99...and a mate gave me some Mavic wheels. So, when the time comes, we are away...
I'm also just about ready to pull the trigger on the 20" Relic myself. With regards to the fork, does it actually do any forking or is it just adding weight for no benefit over rigid?
 

DMan

shawly the least hangeriest guy on rotorburn
What are your thoughts on the relic? My oldest is growing out of his 16 and has a keen interest in mtb, so I'm keen to get him something decent. His height puts him right on the lower limit for the 20" (117cm).
It seems to me the utility of front forks on a 20" is questionable? I was looking at something like a Nukeproof Cub Scout, it's lighter with slightly better kit and hydro brakes, but for 3 times the price I'm not sold on the value vs the polygon.

As far as 26's go, well he's already claimed the Blur downstairs as his, so that's sorted!

Sent from my Pixel 3 XL using Tapatalk
My daughter has a 24" Relic. It's a nice enough bike for the price. But kids twist shifters are crap, so I changed it to a thumb shifter. And fitted some spare hydraulic brakes I had. I agree about the fork. The coil fork even on the 24 really isn't much use. Too hard. But these are cheap and much more versatile.
https://www.cyclingdeal.com.au/parts/forks/24-inch/
 

creaky

XMAS Plumper
I'm also just about ready to pull the trigger on the 20" Relic myself. With regards to the fork, does it actually do any forking or is it just adding weight for no benefit over rigid?
I've been looking around at 20" bikes recently and was seriously underwhelmed with the forks. Coils way too hard to get more than 15mm of travel. Even an $800+ giant XTC SL bike with an air fork was disappointing. It could be setup nice and soft but then the (non adjustable) rebound was WAY too slow and just packed down.

Assume 24" at the same price points would be the same fork specs.

I jumped at a rigid bike with a 2.6" front tyre. Light and should have heaps of grip at 10psi.

@DMan my young fella had a cracker of a blister on his thumb within 10 minutes on the grip shifter yesterday. He found it heaps easier with his gloves on and mastered it quickly thereafter. Why do they spec a harder shifting system on kid's bikes???
 

DMan

shawly the least hangeriest guy on rotorburn
I've been looking around at 20" bikes recently and was seriously underwhelmed with the forks. Coils way too hard to get more than 15mm of travel. Even an $800+ giant XTC SL bike with an air fork was disappointing. It could be setup nice and soft but then the (non adjustable) rebound was WAY too slow and just packed down.

Assume 24" at the same price points would be the same fork specs.

I jumped at a rigid bike with a 2.6" front tyre. Light and should have heaps of grip at 10psi.

@DMan my young fella had a cracker of a blister on his thumb within 10 minutes on the grip shifter yesterday. He found it heaps easier with his gloves on and mastered it quickly thereafter. Why do they spec a harder shifting system on kid's bikes???
Exactly right about the shifter. It was too hard for her to twist properly. The XX1 I had on a different bike in times gone was a 1000X easier to use. The thumb shifter she found easier. It's true about the fork, but at least the air fork compressed. Something the coil with a 30kg kid on it didn't..
Now she doesn't like bikes anyway so it's all moot anyway... :(
 

davee

Likes Bikes
I am wondering about getting my eldest 9yo (who has found the love of his bike after moving out of our flat) a 24" bike as the 20" specialized rip rock is too small.
What are the thoughts on the Commencal Ramones.
Or are the Marin and Polygon a better idea.
 

silentbutdeadly

has some good things to say
I am wondering about getting my eldest 9yo (who has found the love of his bike after moving out of our flat) a 24" bike as the 20" specialized rip rock is too small.
What are the thoughts on the Commencal Ramones.
Or are the Marin and Polygon a better idea.
It comes down to the budget and what sort of future you expect the bike to have...and how comfortable you are with that.
 

creaky

XMAS Plumper
I am wondering about getting my eldest 9yo (who has found the love of his bike after moving out of our flat) a 24" bike as the 20" specialized rip rock is too small.
What are the thoughts on the Commencal Ramones.
Or are the Marin and Polygon a better idea.
Ramones looks way more awesome !

At 9yo they may be close to fitting on a kids / XS 26er possibly, rather than 24.
 
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