# New 2020 kids 20" / 24" / 26" bikes from Nukeproof and YT



## CaptainDecisive (Sep 4, 2007)

It's been a banner week for serious kids MTBs with both Nukeproof and YT launching their new 2020 kids bikes. It feels like we're in some sort of kids MTB golden age right now.

Nukeproof Cub Scout
Nukeproof have released a range of serious hardtails, with two models each with 20", 24" and 26" wheels. There's a lower spec Sport model in each size and a higher spec Race model. The Race models spec the new Manitou Junit forks and Maxxis Minion rubber.
The Singletrackworld Press Release has a nice list of all the sizes, parts highlights, weights etc.
The Nukeproof bikes are up now on the Chain Reaction Cycles website, however it doesn't say when they'll actually be in stock.

YT Jeffsy Primus
YT have also rocked up to the party with their Jeffsy Primus full suspension bikes in 24" and 26" models. Again Manitou have stepped up to handle the suspension and the component spec is aimed at serious riding with a mix of Sram, SDG and Maxxis goodies. Singletrackworld and Pinkbike have more details for you to drool over. Availability on the YT website looks to be mid March.

The pricing for both brands is pretty competitive, or "crazy money to spend on a kids bike" depending on your point of view


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## nobody special (Jun 21, 2019)

I may order a 26 for my 9YO. A little up in the air at the moment because I know he will hate the blue color.

Also what is interesting, is WTB is making a 24" ST i30 rim which is not yet listed on their website. Maybe a good option to what already exists?


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## tobycat2 (May 7, 2011)

those cub scout bikes look pretty good!


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## TimTucker (Nov 9, 2011)

nobody special said:


> Also what is interesting, is WTB is making a 24" ST i30 rim which is not yet listed on their website. Maybe a good option to what already exists?


WTB already had a tubeless i35 20" / 24" rim that was made just for Salsa. Curious if this will have wider availability or if this is another OEM-specific model.

Went ahead and send an email over to WTB to check.

Update -- got a response back from WTB already and these are another OEM-only rim, no aftermarket sales.


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## mark674 (Jan 8, 2020)

Is Chain Reaction Cycles the only online way to go about getting a Nukeproof bike in the US? I'm not too worried about it coming from Ireland, but would be a little more comfortable if there were some other option.

The 26" "Race" builds look pretty great and would save me from wanting to change the drivetrain out. Since the Manitou fork is spec'd to clear 27.5", I wonder if there's room on the rear end to move up to a 27.5" wheel on a 12x142 hub for a future up-sizing when my son grows into it a bit more. The only other thing I'd consider is swapping on some shorter crank arms if its needed until my son grows into the 160mm. Overall, this reminds me a lot of the Cleary Scout.


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## GSJ1973 (May 8, 2011)

mark674 said:


> Is Chain Reaction Cycles the only online way to go about getting a Nukeproof bike in the US? I'm not too worried about it coming from Ireland, but would be a little more comfortable if there were some other option.


Yup, Chain Reaction owns both Nukeproof and Vitus. You can get them only from Chain Reaction and Wiggle who are also both owned by the same company.

The Nukeproof kids bikes look really nice. The heavy wheelset/tire spec is where the weight is and IMHO worth upgrading immediately...similar to the Vitus spec. But then you get into the realm of so many other kids bikes for just a few bills more with lighter wheels from the beginning. Great entry level bikes at a more entry level price though. Cool to see so many new options!

" Nukeproof is a similar story. Once a U.S.-based gravity-focused component maker, Chain Reaction bought the brand off the scrap heap, then slowly built it back up, adding bikes to the product line, and even sponsoring a World Cup downhill team that includes multi-time world champion Sam Hill. "


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## rabitoblanco (Feb 21, 2017)

GSJ1973 said:


> Yup, Chain Reaction owns both Nukeproof and Vitus. You can get them only from Chain Reaction and Wiggle who are also both owned by the same company.
> 
> The Nukeproof kids bikes look really nice. The heavy wheelset/tire spec is where the weight is and IMHO worth upgrading immediately...similar to the Vitus spec. But then you get into the realm of so many other kids bikes for just a few bills more with lighter wheels from the beginning. Great entry level bikes at a more entry level price though. Cool to see so many new options!
> 
> " Nukeproof is a similar story. Once a U.S.-based gravity-focused component maker, Chain Reaction bought the brand off the scrap heap, then slowly built it back up, adding bikes to the product line, and even sponsoring a World Cup downhill team that includes multi-time world champion Sam Hill. "


That's pretty amazing, I had no idea of their back story.

What do y'all reckon between the Race and Sport 24? 
For the kind of riding we like to do, a 9 or 10 speed doesn't make a difference--and neither drivetrain is particularly impressive. Meanwhile the Sport gets the shorter 140mm cranks.

Obviously the fork is big-- I have an RST F1rst I could swap in-- ideas in how that compares?

-Ridwan

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## nobody special (Jun 21, 2019)

Between the race 24 and sport 24, I'd buy the race 24. This is my opinion though, and mostly due to laziness of not wanting to swap anything out. However, between the Commencal Meta HT 24 or Nukeproof Race 24, for exactly the same price, the Commencal is the better bike, in my opinion. Shorter chainstays will be easier to wheelie and the components specs are equivalent or better.

My (currently) 55" tall 9YO has been riding 152mm cranks for two years, they seem to fit him fine.

I would be ordering a Commencal 24 but I decide to move my son up to a 26" bike. When the Nukeproof Race 26 gets in stock I'm going to order it.


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## GSJ1973 (May 8, 2011)

CaptainDecisive said:


> YT Jeffsy Primus
> YT have also rocked up to the party with their Jeffsy Primus full suspension bikes in 24" and 26" models. Again Manitou have stepped up to handle the suspension and the component spec is aimed at serious riding with a mix of Sram, SDG and Maxxis goodies. Singletrackworld and Pinkbike have more details for you to drool over. Availability on the YT website looks to be mid March.
> 
> The pricing for both brands is pretty competitive, or "crazy money to spend on a kids bike" depending on your point of view


Anyone here get their YT Primus yet? Any first impressions? A friend of a friend got one last week and mentioned severe seat stay chain rubbing, and then bike is heavier than advertised at 28.5 pounds, not that weight really matters on a shuttle bike.


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## wallander (Jul 22, 2018)

GSJ1973 said:


> Anyone here get their YT Primus yet? Any first impressions?


Bumping the question.

I was going to order a Primus 24 now, but they just went out of stock. YT replied to me that they don't know when they'll be in again.


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## Marshfly (Jul 20, 2019)

What's everyone's thoughts on the Nukeproof Cub Scout Race 20" vs the Commencal Meta HT 20? 

Seems the biggest differences are a 127mm crank on the Nukeproof rather than a 145mm on the Meta and narrower tires on the Nukeproof which should be lighter.

This will be for my 5yo. He's on a Trek Superfly 20 that I bought used right now and I'm tired of fighting the v-brakes rubbing every time he falls on it.


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## m1tch666 (Jun 20, 2014)

Anyone had any experience with these? They seem reasonably spec'd and very light.

https://squish.bike/product-category/mtb/


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## Autoxfil (Sep 18, 2019)

I'm about to get my 11 year old off the mediocre 24" Riprock that he's outgrown. 

I had decided on the Cub Scout Race 26", but I was told they are already sold out. That seems nuts since they just came out, but maybe it's true. My only reservation was the super-low BB height (47mm drop on a 26er?)

The Commencal Meta HT Jr looks good. I don't know that my son really needs a 150mm fork - I get by just fine on our trails with a 120mm on my SB100. It's a heavier bike, although much of that is probably tires and tubes. The dropper is nice but of course adds weight. SX is good, but again - weight. Shipping is also more, so it's $1340 delivered. I'm sure it's awesome and I'd be happy long-term, but it also seems like it might be a bit of a pig for a while. 

The Cleary Scout 26" looks good. Decent 100mm air fork, more XC geo (69HT vs 66 on the other bikes, although still a long HT/short stem), nice short chainstays, and the 28x11-42 gearing that I think is perfect. It's not as aggressive geo, and no dropper routing. I do like the Vee Crown Gem tires. I think it makes a really good XC bike, but probably won't send it like the others. 165 cranks are dumb and might get swapped. $904 shipped isn't too bad. 

Or, I could get the Cub Scout Sport, which is $800 shipped. It's the worst fork of the bunch, but still an air fork. Gearing is only 30x11-36, which is tolerable but the worst of the bunch. It still comes with tubeless minions and dropper routing, so it should be a shredder. 


I might be projecting a bit as I lean towards the Cleary, since I'm more of an XC guy. He's not a real ripper, but he certainly likes the down. He does like clearing a techy climb, though, and the Cleary should do that very well. 

Any opinions?


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## Marshfly (Jul 20, 2019)

If you are contemplating spending $1340 on the Commencal just get the Spawn Yamma Jamma 26" for $1395. Way lighter and an upgrade to NX over SX. I bought that for my 9yo for Christmas and it is a fantastic bike and build. They have $40 flat rate shipping.


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## Autoxfil (Sep 18, 2019)

Marshfly said:


> If you are contemplating spending $1340 on the Commencal just get the Spawn Yamma Jamma 26" for $1395. Way lighter and an upgrade to NX over SX. I bought that for my 9yo for Christmas and it is a fantastic bike and build. They have $40 flat rate shipping.


Thanks! I think I'd dismissed them as a DJ company, mostly from the angle of the seat in the photo of the Yamma Jamma, but it does look like trail-bike numbers. I agree that looks better than the Commencal for the money- better fork, better drivetrain, and I can easily swap to a 28t chainring. Lighter tires and lower weight overall, too.

I heard 26.5lb with pedals and tubes. Did you happen to weigh yours?

$800 for a Nukeproof that will get the job done but I'd be tempted to upgrade gearing.
$900 for a Cleary that's XC-ready but might not be rad enough
$1440 is a big step up in coin, but it would be a do-it-all rig with no compromises.

Hmmm....


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## nobody special (Jun 21, 2019)

I read all the posts on this site but I bought the Commencal anyway because I got tired of waiting for the Nukeproof Race 26 to come into stock.

Honestly the weight and chainstays don't really seem to make a difference to my kid. Everything he could do on his old 28lb, 24", bike, he can do way better on his new 30lb, 27.5", bike. Except for wheelies, those are still the same.

I thought I was done buying bikes for a while but my 7YO daughter jut started riding the old 24" and now I'm back to looking for a new 24 because I'm not going to spend any money on the old 24.


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## Autoxfil (Sep 18, 2019)

Marshfly said:


> If you are contemplating spending $1340 on the Commencal just get the Spawn Yamma Jamma 26" for $1395. Way lighter and an upgrade to NX over SX. I bought that for my 9yo for Christmas and it is a fantastic bike and build. They have $40 flat rate shipping.


My son and I pored over the bikes last night, and then slept on it. This morning we ordered the Spawn and a 28t chainring. The Reba is a pretty huge deal - I like having a real fork that will last forever if I maintain it. 11-42 NX is awesome, and with the 28t it'll offer a wonderful granny gear. The tires (HRII) are probably a little heavier than he needs, so I might swap them out for some Rocket Rons or something, but I'll see how he gets on with them. They will certainly be good winter/mud/wet tires.


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## nwa bike dad (Apr 21, 2018)

Autoxfil said:


> My son and I pored over the bikes last night, and then slept on it. This morning we ordered the Spawn and a 28t chainring. The Reba is a pretty huge deal - I like having a real fork that will last forever if I maintain it. 11-42 NX is awesome, and with the 28t it'll offer a wonderful granny gear. The tires (HRII) are probably a little heavier than he needs, so I might swap them out for some Rocket Rons or something, but I'll see how he gets on with them. They will certainly be good winter/mud/wet tires.


You'll be really happy with that. YJ's are such great bikes. The difference in what he's coming from will be enormous!


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## svinyard (Aug 14, 2017)

Ditto, super cool bike and well balanced. Let us know how the fork is. I'm guessing it'll be really nice from the specs/tune of it.


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## Autoxfil (Sep 18, 2019)

svinyard said:


> Ditto, super cool bike and well balanced. Let us know how the fork is. I'm guessing it'll be really nice from the specs/tune of it.


I had a Reba on my Fuse, and it was very nice. As light as a SID, and just as plush for moderate riding. Both chassis and damper got overwhelmed a bit when really hammering on it, but hopefully that won't be an issue for a kid.

I haven't regretted spending more on a bike yet, but I've regretting spending less several times...


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## svinyard (Aug 14, 2017)

Autoxfil said:


> I had a Reba on my Fuse, and it was very nice. As light as a SID, and just as plush for moderate riding. Both chassis and damper got overwhelmed a bit when really hammering on it, but hopefully that won't be an issue for a kid.
> 
> I haven't regretted spending more on a bike yet, but I've regretting spending less several times...


Lol yeah that upfront price pain does go away REAL fast.

The nice thing about this 26" Reba is that its a KIDS Reba with a kids tune etc. Its a big upside in our experience if kids are pushing it in the chunder. It will track like an adult fork would. Plus you can mess with tokens a bit which might be helpful. If they made a Debonair air spring (40$) that fit it...that would be sick! I like the dual chamber stuff at low PSI's that kids run.


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## Autoxfil (Sep 18, 2019)

svinyard said:


> The nice thing about this 26" Reba is that its a KIDS Reba with a kids tune etc.


Yup, that's the biggest reason I went with a kid's bike and not something like an XS Fuse. I'm 150lb and ride hard, but I still run most forks pretty much wide-open on rebound. My 65lb son isn't going to get good performance with an adult fork!


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## Marshfly (Jul 20, 2019)

So I got trigger happy this morning too. My 5yo has a Trek Superfly that I bought used last summer that I've been trying to keep up and I'm tired of messing with the cheap shifter/derailleur and V-brakes.

I've got one of the Sale Price Trailcraft Blue Sky 20 Special Builds with the suspension fork upgrade on the way.

I realized that $1200 was really not that much more than $900 for the Commencal or Nukeproof to save almost 4 pounds and bump to a much better drivetrain. Can't wait to se him on it.


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## nwa bike dad (Apr 21, 2018)

Marshfly said:


> So I got trigger happy this morning too. My 5yo has a Trek Superfly that I bought used last summer that I've been trying to keep up and I'm tired of messing with the cheap shifter/derailleur and V-brakes.
> 
> I've got one of the Sale Price Trailcraft Blue Sky 20 Special Builds with the suspension fork upgrade on the way.
> 
> I realized that $1200 was really not that much more than $900 for the Commencal or Nukeproof to save almost 4 pounds and bump to a much better drivetrain. Can't wait to se him on it.


Sick bike. And the resale on those is crazy. If you ever find one in our area on sale its gone in minutes for 70% - 80% of what they probably paid.


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## svinyard (Aug 14, 2017)

That is a smoking deal dude. That'll likely be 2-3lbs in rotational weight saved too.

What is the suspension fork upgrade? They come with the TC30 (their version of the Spawn/Prevelo/Lil Shredder fork). Is there something better they are spec'ing?


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## Marshfly (Jul 20, 2019)

svinyard said:


> That is a smoking deal dude. That'll likely be 2-3lbs in rotational weight saved too.
> 
> What is the suspension fork upgrade? They come with the TC30 (their version of the Spawn/Prevelo/Lil Shredder fork). Is there something better they are spec'ing?


The special is $849 with an aluminum rigid fork and 10 speed GX. The suspension fork is a $379 upgrade. When I called to see about shipping time he told me almost everyone was adding the fork.

https://www.trailcraftcycles.com/product/blue-sky-20-special-build/

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## Marshfly (Jul 20, 2019)

Btw they also have sales on special builds of some of the 24 and 26 inch bikes so take a look before you hit Add To Cart anywhere else. 


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## svinyard (Aug 14, 2017)

Marshfly said:


> The special is $849 with an aluminum rigid fork and 10 speed GX. The suspension fork is a $379 upgrade. When I called to see about shipping time he told me almost everyone was adding the fork.
> 
> https://www.trailcraftcycles.com/product/blue-sky-20-special-build/
> 
> Sent from my iPhone using Tapatalk


Gotcha, I like that fork a lot (we have it on 20" YJ). It has a limit but most kids at this age and weight aren't going to find it. It works super well and isn't just like a DJ fork for them but actually soaks up the chunder while being fairly light at 1435g. Fwiw you should ask them if it has the big polastic bottom out bumper installed. That will eat up about 15mm of actual travel unnecessarily while also preventing the air from stacking up enough to ramp up. I made a video on shaving it down and servicing the fork. It's fairly easy. Highly recommended or ask Brett to do it. You want the full travel imo.


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## Marshfly (Jul 20, 2019)

svinyard said:


> Gotcha, I like that fork a lot (we have it on 20" YJ). It has a limit but most kids at this age and weight aren't going to find it. It works super well and isn't just like a DJ fork for them but actually soaks up the chunder while being fairly light at 1435g. Fwiw you should ask them if it has the big polastic bottom out bumper installed. That will eat up about 15mm of actual travel unnecessarily while also preventing the air from stacking up enough to ramp up. I made a video on shaving it down and servicing the fork. It's fairly easy. Highly recommended or ask Brett to do it. You want the full travel imo.


Good info. Got a link to the video?

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## svinyard (Aug 14, 2017)

Marshfly said:


> Good info. Got a link to the video?
> 
> Sent from my iPhone using Tapatalk


Its just a very poorly made YouTube video but there was literally no other documentation on how to do this...so Brian was nice enough to invite me over and go through it. A lot of kids owe that guy for kicking off the whole kids-MTB-Bike stuff. Very cool guy. His kid is pretty unreal rider too.


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## rtc1930 (Jun 3, 2016)

*New 2020 kids 20" / 24" / 26" bikes from Nukeproof and YT*

I was considering the 20" special edition trailcraft as well but ended up going with the 20" nukeproof. We just got it last week and the bike has been great so far and my son loves it. The trailcraft is for sure better as far as weight goes but didn't want to stretch the budget that far.

That said I was hoping to purchase a 24" bike as well and was circling around the same 3 brands, commencal, nukeproof, and trailcraft but it seems inventory is a disaster for bikes right now. The few I was considering have all gone out of stock and Commencal just told me theirs likely won't come back in stock till mid to end of summer. I was trying to hold out for the nukeproof over the Commencal to save a few bucks since the spec is similar but Nukeproof has not gotten back to me and commencal just sold out in the last day or two so i missed my opportunity. I could still do the trailcraft but the special builds are not available right now either and normal builds are twice what i wanted to spend.

In my research, I've reached out to multiple local shops and looked into a few of the mid level offerings but it seems stock is dried up on most of those as well. Hoping I can get a decent bike before they grow out of the size I'm trying to buy.

The trailcraft looks sweet though and the discussion here has renewed my interest.


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## nobody special (Jun 21, 2019)

Wow, I was looking at the 24s for my 7YO and now they are all out of stock. I did not realize that. I was looking at them last week and there were at least two in stock last week.

Maybe there will be good deals on used ones in a couple months.


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## RMCDan (Feb 28, 2008)

svinyard said:


> Gotcha, I like that fork a lot (we have it on 20" YJ). It has a limit but most kids at this age and weight aren't going to find it.


I still have the 100 mm thru-axle version from my kid's old Rokkusuta 20 on his DJ. It's still kicking a$$:


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## svinyard (Aug 14, 2017)

RMCDan said:


> I still have the 100 mm thru-axle version from my kid's old Rokkusuta 20 on his DJ. It's still kicking a$$:


Ha. Same. We are just using the Yama Jama 20" as the DJ. What are you using for a frame?


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## RMCDan (Feb 28, 2008)

svinyard said:


> Ha. Same. We are just using the Yama Jama 20" as the DJ. What are you using for a frame?


Using the Flow frame we got him when he first moved up to 20" wheels. Perfect DJ bike. Also has Hayes Dominion A4 brakes F/R, LOL.


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## rabitoblanco (Feb 21, 2017)

Marshfly said:


> Btw they also have sales on special builds of some of the 24 and 26 inch bikes so take a look before you hit Add To Cart anywhere else.
> 
> Sent from my iPhone using Tapatalk


Since I can't get the Nukeproof, seriously thinking about that Big Mesa special, with the 27.5 Stan's on it. 
Or the 26 YJ

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## Marshfly (Jul 20, 2019)

rabitoblanco said:


> Since I can't get the Nukeproof, seriously thinking about that Big Mesa special, with the 27.5 Stan's on it.
> Or the 26 YJ
> 
> Sent from my Pixel 3a using Tapatalk


My 10yo has the YJ 26. He loves it. Good build at a good price.

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## ggphysics (Jul 31, 2017)

I'm also looking at the CubScout vs YJ 26. Is the YJ a decent all around bike?. i.e. can the kids climb twisty technical trails, ride pump track, and generally ride xc type stuff in New England? 

My son has outgrown his Islabikes creig 24 this spring and I'm getting ready to pull the trigger.


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## Marshfly (Jul 20, 2019)

ggphysics said:


> I'm also looking at the CubScout vs YJ 26. Is the YJ a decent all around bike?. i.e. can the kids climb twisty technical trails, ride pump track, and generally ride xc type stuff in New England?
> 
> My son has outgrown his Islabikes creig 24 this spring and I'm getting ready to pull the trigger.


My kid does all of that with his.

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## Autoxfil (Sep 18, 2019)

ggphysics said:


> I'm also looking at the CubScout vs YJ 26. Is the YJ a decent all around bike?. i.e. can the kids climb twisty technical trails, ride pump track, and generally ride xc type stuff in New England?
> 
> My son has outgrown his Islabikes creig 24 this spring and I'm getting ready to pull the trigger.


The geometry says yes, but I can tell you for sure next week - the bike arrives Wednesday, and the weather looks excellent.

The only change I'm planning on right away is swapping the 32t for a 28t, which I ordered when I bought the bike. After his legs are fried I'll take the time to tear the whole thing down, weigh each part, convert to tubeless, and fine-tune the shock and tire pressures. I'll post all the weights here.


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## ggphysics (Jul 31, 2017)

Thanks for the replies. I'm looking forward to your feedback.


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## nwa bike dad (Apr 21, 2018)

ggphysics said:


> I'm also looking at the CubScout vs YJ 26. Is the YJ a decent all around bike?. i.e. can the kids climb twisty technical trails, ride pump track, and generally ride xc type stuff in New England?
> 
> My son has outgrown his Islabikes creig 24 this spring and I'm getting ready to pull the trigger.


You can ride the pump track with a YJ but a 26" MTB is not going to be as fun for him. It's a great bike. Find a cheap used BMX if you do a lot of pump track stuff. A lot of these guy like the Park bikes. My son has a JR DK 20" Race BMX that was not expensive and flies around the pump track.


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## ggphysics (Jul 31, 2017)

I'm sure most of you are familiar of the exercise that I just did. I found a used Kona Fire Mountain XS frame on Ebay. About $250. I then proceeded to price out the build and incorporated some parts that I had on hand. Without a dropper post, using my bars, stem, derailluer/shifter the total can to $1300. That's a used frame with a Reba fork, decent wheels, etc. These bike prices don't look so inflated once you build your own on paper.


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## svinyard (Aug 14, 2017)

Marshfly said:


> My kid does all of that with his.
> 
> Sent from my iPhone using Tapatalk


How is that kids Reba fork? Is the tune on it nice for the kid?


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## Marshfly (Jul 20, 2019)

svinyard said:


> How is that kids Reba fork? Is the tune on it nice for the kid?


We can definitely get proper sag out of it. The chart on the lower has pressures for 60-120# riders so it's definitely designed for kids.

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## Autoxfil (Sep 18, 2019)

I didn't strip the new Yama Jama down before building it up - my son was too excited, and I was meeting friends to ride myself. So the full weighing and re-building will wait for a rainy day.

For now, here's my info. Not to bury the lead: he likes it, but of course he does. My riding impressions don't count, so I'll just evaluate him as we go, and try to provide some context for where he struggles and where he makes big leaps in his riding on this bike.

Measurements align with Spawn's, but since their chart is missing some critical numbers, here are a few:

HT 68.3 (they had 68, just checking)
Seat tube angle 73.2
Reach 393
Stack 610
BB height of 295
BB drop of -44

The 2.3 High Rollers are dual-compound, EXO/TR, 2.3". They measure out at 2.25" on these rims at ~15 psi. The frame has 1/2" (more like 13mm) clearance to the DS chainstay, which is the tight spot. So a 2.5" tire will easily fit. 2.6" should be fine as well. There is over 1" to the seat stay bridge, and 1.5" to the BB, so mud clearance won't be an issue, even with big meats.

The fork clearance is a little tighter, about 12mm to the bridge. There is 137mm to the crown, so no worries there - if it clears the bridge, it'll clear the crown at full compression (not the case with all forks!)

27.7lb with the included pedals, tubes still in the tires, and the chain guard in the rear spokes. That doesn't count the plastic baggie of reflectors, when obviously went straight into the parts bin in the sky.

50lb in the Reba resulted in ~20% sag for a 65lb kid. Rebound feels good to me about 4 clicks from fully open, out of 20. This is less than the 25-40 psi printed on the lowers for 60-80lb, so I'll double-check the sag and watch his travel usage. At the moment the o-ring says he could use less pressure, it's only 60% of the way up the stanchion and he was jumping the bike.

He's very skinny, and at 4'9" with long legs, he's going to be out of seatpost way before the 393mm reach is an issue.

There is 318mm of room in the seatpost for a dropper, minus some for cable routing, which looks like it would get pinched if you tried to slam the post fully. That looks like most 125mm droppers will work fine, and maybe a 150 if it's got efficient packaging.

The finishing kit is clearly where they saved money. Things which are very cheap-feeling:

Post and saddle, which have a plastic mount (no saddle rails) which adjusts with a hex through the top of the saddle. On the plus side, it's extremely light. I might move this to his sister's Salsa to save weight on that, when he gets a dropper.
Taya Onza Chain. It feels like crap.
The stem looks massive, but I'd guess won't be all that heavy when I weight it. Tolerances are clearly not great.
Front thru-axle doesn't look like a Rock Shox, it's very cheap, but does seem to work.

The cranks and chainring are decent - I didn't install the 28t I ordered yet, but it's 70g. Oddly, the chainline is 52mm, despite running 135mm rear spacing. There are spacers in the BB stack, with 2 on the driveside and 1 on the NDS, so that's an easy fix, but a stupid assembly decision. With 415mm chainstays, a too-wide chainline is very obvious. I prefer 47mm over 49mm, if there's tire and chainring clearance.

I don't want to sound like I'm complaining too much - I'm not uphappy, just pointing out that you don't get NX 11 and a Reba and Maxxis tires on a $1400 kids bike without and compromises. In my opinion all the cheaper parts were smart decisions, except the silly spacers on the BB, but that's probably just excessive caution with chainring clearance.

Oh, these Wellgo pedals are great. Never thought I'd say that! They are narrow, so they don't catch the trail as easily as adult platforms, and have gippy, but wider spikes that should be more friendly to young shins. I think they will stay on the bike.

I'll report back with detailed weights after I ditch the tubes.


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## TimTucker (Nov 9, 2011)

Autoxfil said:


> I didn't strip the new Yama Jama down before building it up - my son was too excited, and I was meeting friends to ride myself. So the full weighing and re-building will wait for a rainy day.
> 
> The finishing kit is clearly where they saved money. Things which are very cheap-feeling:
> 
> ...


Some notes on this:

Spawn uses Pivotal saddles -- they're actually not any cheaper than railed saddles, though there may be some cost savings from using the same saddles across their lineup. In addition to the weight savings, the stack height is significantly lower than railed saddles. On their smaller sizes it cuts minimum saddle height down by 1-2" vs. other bikes of the same size -- enough that it's possible to size some kids one tire size up and still have a good fit. If kids are tall enough that they don't need the seat slammed, there's less of a benefit.
Spawn's stems are built / designed much closer to BMX stems than MTB stems. If the stem on the Yama Jama is anything like the stem on the Yojis, massive is a good indication of heavy. Going to something like a Wren stem is usually good for saving around 150-200g.


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## Autoxfil (Sep 18, 2019)

Cool, thanks for the info. The Pivotal saddles are interesting and do seem to have the stack and weight advantages, but certainly shouldn't be more expensive - if they are it's just economies of scale. 

Salsa railed post and saddle - 653g
Brood/Pivotal post and saddle - 465g.

200g is pretty significant! 465g would be expensive to hit with railed saddles and posts, probably at least one would need to be carbon. 

I just popped off the BB - there's tons of room in the crank splines to pull those spacers, and with the 28t it'll give plenty of frame clearance. So that's an easy fix. 

Also, I'm so glad they didn't go internal routing. Especially for brakes, I love being able to pull the whole thing without opening the hydraulic system. That and 12-speed are both things that most new adult bikes in the <$1500 range have, just because people are "spreadsheet shopping" and more features = more better.


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## TimTucker (Nov 9, 2011)

My guess on the Pivotal stuff is that it's part economies of scale and part licensing costs, since the interface is new enough to still be patented (which probably also drives down the scale):
Pivotal Components

Looks like the patent expires in 2023 -- wouldn't be surprised to start seeing it more widely adopted after that:
https://patents.google.com/patent/US6899389B2/en


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## Autoxfil (Sep 18, 2019)

Yesterday afternoon was cold and rainy, so we broke the bike down and re-built it. A spreadsheet with complete weights is attached. 

Highlights:
Frame is 2269g (5.00lb) with derailleur hanger, headset, and bottle cage bolts. 
Fork is 1565g (3.45lb) with star nut but no brake bolts

I weighed the wheels with the rotors on, but assuming 178g per rotor (the weight of some identical-looking TRP 160mm rotors that came on a cyclocross bike I have), the wheels are
1031.7 rear
931.8 front
1963.5 for the wheelset, with tubeless tape (not included, they came with tubes)

Stem is 196. So, maybe I will grab a Wren and drop 100g+. I wish Race Face made the Ride stem in lengths shorter than 60mm. 

Frame is as heavy as I'd feared, the fork is as light as I'd hoped. Wheels are about what I expected. 

Riding seems good so far! When the weather breaks we will get into some serious trails.


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## Autoxfil (Sep 18, 2019)

Swapping stem and bars dropped 260g. I spend $70 total on eBay carbon bars and a Wren stem, which greatly exceeds the $0.50/gram rule I established for this bike!

I left the bars at 760mm for now since he was loath to cut them, but that seems nuts for his size. I might need to wait until he hooks a tree trunk before he is willing to chop them. 

Of course it's hard to tell how well the bike works with feedback coming through the wide eyes of a pre-teen. It's massively better than his old Spesh, which is his only comparison. He certainly jumps it fine despite the much bigger size.


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## rtc1930 (Jun 3, 2016)

Got tired of waiting for the 24" nukeproof to come in stock and jumped on the Commencal when it came back in stock for a short time last week. I still think the 24" Nukeproof had a slightly better spec and we love the 20" nukeproof so far but the kids seem to like the short chain stays on the Commencal. They can throw it around just as easy as their 20".

It's no Yama Jama and I'm not a fan of skin wall tires but the kids like them.










Sent from my iPhone using Tapatalk


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## CaptainDecisive (Sep 4, 2007)

FYI, 2021 Nukeproof Cub Scouts in 20", 24" and 26" are now available on the Chain Reaction Cycles site.
They might not last for long.


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## jaybert (Sep 10, 2020)

Ordered a 24" race from chain reaction cycles...talked to my LBS and they ordered only 26" and he said all 20 and 24" were sold out for the season already from nukeproof. My son (7yo, 46.5") is probably too small for it right now (didn't want to buy a 20" he would outgrow in a year or two) but figure I can unload it new in box for what I paid for it and hopefully grows taller over the winter.



CaptainDecisive said:


> FYI, 2021 Nukeproof Cub Scouts in 20", 24" and 26" are now available on the Chain Reaction Cycles site.
> They might not last for long.


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## chiefsilverback (Dec 20, 2019)

jaybert said:


> Ordered a 24" race from chain reaction cycles...talked to my LBS and they ordered only 26" and he said all 20 and 24" were sold out for the season already from nukeproof. My son (7yo, 46.5") is probably too small for it right now (didn't want to buy a 20" he would outgrow in a year or two) but figure I can unload it new in box for what I paid for it and hopefully grows taller over the winter.


As soon as the 26 Race turns up for my 9yo the 49" 7yo will be on our 24" Pello Reyes. Your son might need to grow a little bit for the Nukeproof, but maybe a shorter stem, bars and cranks if he doesn't shoot up in time.


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## jaybert (Sep 10, 2020)

Yea I was looking at a shorter crank. The ones they have on the 20", 127mm is probably the right size for him. I was trying to figure out what my options are (pretty newb when it comes to bikes, just getting into it now because my son is).

We will hopefully make it until Christmas but I don't know if his current bike (cannondale trail 20 6 speed) will last until then. It was dropping the chain up front So we brought it to the shop and they swapped out the rear derailleur. Problem is it's an adult sized derailleur so it sits REALLY low. When in 1st it's like 1/2" from the ground. They said they could put the old one back on but that wouldn't really do me any good either. My guess is it's going to get messed up in short order given how low it is. When we go downhilling again I'll need to make sure he's in a higher gear to keep it out of the way.



chiefsilverback said:


> As soon as the 26 Race turns up for my 9yo the 49" 7yo will be on our 24" Pello Reyes. Your son might need to grow a little bit for the Nukeproof, but maybe a shorter stem, bars and cranks if he doesn't shoot up in time.


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## chiefsilverback (Dec 20, 2019)

jaybert said:


> It was dropping the chain up front So we brought it to the shop and they swapped out the rear derailleur. Problem is it's an adult sized derailleur so it sits REALLY low.


Was it running the Shimano Tourney derailleur? Those things fall apart if you look at them. My 5 year old is on a Quick 20 and he was struggling with the grip shift, especially when his hands get a bit sweaty. I tell friends who have kids bikes with the Tourney to order a spare.

I upgraded the Pello to the new Microshift Advent X, and put the SRAM X5/7 that came off the Pello onto the Cannondale. The only problem was that the Cannondale is a 7 speed and the SRAM was a 9, so I had to drop the smallest sprocket and set the limit screws to block out the 9th position.


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## jaybert (Sep 10, 2020)

chiefsilverback said:


> Was it running the Shimano Tourney derailleur? Those things fall apart if you look at them. My 5 year old is on a Quick 20 and he was struggling with the grip shift, especially when his hands get a bit sweaty. I tell friends who have kids bikes with the Tourney to order a spare.
> 
> I upgraded the Pello to the new Microshift Advent X, and put the SRAM X5/7 that came off the Pello onto the Cannondale. The only problem was that the Cannondale is a 7 speed and the SRAM was a 9, so I had to drop the smallest sprocket and set the limit screws to block out the 9th position.


Not sure...i believe the old one was a Shimano but the model I dont remember. I mean it was only $100 for the new derailleur, a new chain, and new shifter cable, and installation, so not a huge investment/cost if anything happens. My guess is it'll be fine riding around the neighborhood, but will need to be extra careful when we go trail riding or downhilling to stay in 1 of the higher gears to get more clearance.


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## rton20s (Aug 27, 2010)

jaybert said:


> Not sure...i believe the old one was a Shimano but the model I dont remember. I mean it was only $100 for the new derailleur, a new chain, and new shifter cable, and installation, so not a huge investment/cost if anything happens. My guess is it'll be fine riding around the neighborhood, but will need to be extra careful when we go trail riding or downhilling to stay in 1 of the higher gears to get more clearance.


The bike shop who did the derailleur swap should have never put something on that hangs "like 1/2" from the ground" in any gear. They put in a derailleur with too long of a cage. This is especially problematic with kids bikes which are much more likely to be abused and dropped on the drive side of the bike. There is no reason the derailleur should even be as low as the rim, much less as low as what you described.

After trying to address chain drops on my son's 20" bike with derailleur and chain guide adjustments and swaps, what ultimately worked best for us was swapping out the cranks and chain ring. We went with a set of the Spawn 127mm cranks with 32T narrow-wide chain ring and chain guard with a KMC 9 speed chain. (We also swapped the bottom bracket for a different width to keep the correct Q factor.) With the OE Shimano Altus M310 derailleur, we have all but eliminated chain drops. Even when back pedaling, which used to be an instant drop.


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