# Carbon Frame XS 26" Build



## stom_m3 (Jun 28, 2011)

Well I finally finished my son's XS Chinese carbon frame 26" wheel build. To cut to the chase, here is the end result;



If you would like to know more, continue reading 

So to start, my son is 4' 7" and fits his Scott Scale RC Jr 24" perfectly. That said, he could stretch into an XS 26" frame and benefit from the larger rolling diameter of the 26" tire. I got the idea of building an XS Chinese carbon frame from XC71's post (very trick bike). So I started my quest of looking for the smallest frame I could find. I emailed all the usual suspects XMIplay, Flyxii, HongFu, DengFu, Yoeleo, LT Bike, Miracle Bike, and XM Carbon Speed.

A lot of frames came in 15 or 15.5" but I was hoping for something in 14". Peter (formerly XMIplay) at XMCarbonSpeed said that he actually had a Cube frame in 14" that he was building for his wife but was now pregnant and so he wanted to sell it. He gave me a fair price and I agreed to purchase it. I felt comfortable enough since Peter's name was plastered over the various forums and had a good rep for being timely and honest. All of my dealings with him so far back this up.

Now that the frame was secured, I started to opportunistically buy 26" components. Lucky for me everyone was blowing out 26" specific items at very cheap prices (mainly purchased at Pricepoint and JensonUSA).

As for configuration, I wanted to build an XT level spec bike. I wanted to have something that was a little more bulletproof. With the new M8000 XT coming out, the previous generation XT stuff was also at decent pricing. Here is the final build sheet;



Lessons learned;

Rockshox SID RCT3 looks like it will work for his weight. I was concerned because the lowest pressure rating on the shock is 70psi for 140lbs. I was able to run it at 35psi with good results. Also, Rockshox now provides a pump and rebuild kit with all of their forks.
Shimano Pre-bled brakes will need to be cut regardless because the hoses are so long.
Shimano brakes take a fraction of the time to bleed as Avids and Formulas
The Wolf 42T cog shifts awesome
Carbon splinters really hurt and 1 splinter is actually multiple fibers that all need to be removed... ouch!
Buy a bike stand with a tray holder

Here are additional pictures during the build. Enjoy;
Frame, Seatpost, and Seat.


Rockshox SID RCT3 Tapered, 100mm travel


Checking crank and fork fit


Removed the 3X chainring setup and added Race Face BG. Also changed the cassette to an 11-42 wide (removed 15t/17t, added 16t/42t)


Routing the cables for the rear derailleur.


Next day it started raining so I had to move operations indoor. I bought the pre-bled brakes but it doesn't matter because the pre-bled hose lengths are WAY to long. That said, Shimano brakes are so easy to bleed compared to my Avid Elixer CR's and Formula R1's. Picture shows test fitting brakes and determining the correct length.


Finished all cable lengths and added blue grips.


Picture of bashring and inside chain keeper


Only thing left is to cut the steerer and seatpost.


And complete.


Time to hit the trail!


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## POAH (Apr 29, 2009)

why did you go with a bash rather than a standard N/W and the long crank arms for a small kid?


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## Szy_szka (Oct 29, 2015)

Great write-up! Thanks for sharing!


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## stom_m3 (Jun 28, 2011)

POAH said:


> why did you go with a bash rather than a standard N/W and the long crank arms for a small kid?


Actually, I don't have any experience using the NW chainrings and didn't want to risk dropping chains. My current setup is pretty robust from that. What has been your experience with the NW chainrings?

As for the crank length, I'm all for proper fitting cranks but I got lazy. His height would best fit 150-155mm crank length. I'm pressing him into the 165mm cranks. We went for a ride this morning and he seemed ok with the current length. He can't spin them as easily as his shorter cranks but he doesn't do so bad. Do you know of a 2 piece crank that comes in shorter sizing with 24mm spindle?


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## POAH (Apr 29, 2009)

I've never dropped a chain with my N/W and clutch mech and lewis hasn't with his ripcord either. as for the crank I don't know, there is a short two peice with an external BB but can't remember the name or the axle size. it's mentioned in the crank thread in this forum.


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## stom_m3 (Jun 28, 2011)

It was a successful maiden voyage for my son's new bike. He liked how it handled and how light the bike felt. The 42T goat gear in the back was insane for going up some of the hills. He was actually able to stay in the saddle longer than I was on some of the steeper climbs.

One of the biggest surprises was the fork and being able to handle the lower weight. I'm currently running about 35psi and seems to work very well for his weight. He's getting full 100mm of travel out of the fork.

I may swap the carbon seat for one that actually has padding but he hasn't complained about it yet. I'll give it another couple of rides and ask him. I'll probably just swap his Scott seat for it.


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## xc71 (Dec 24, 2008)

Looks great Stom! He's gonna love riding it.


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## Erock503 (Oct 20, 2014)

Man, that looks ridiculously cool! I've had no problem taking chances on the Chinese products for myself as long as they aren't knockoffs, but I've been hesitant for my little guys. This looks to be a product they market as their own though correct? That would really take a big chunk out of the weight, man that is tempting. 

I take it your guy is very skilled though right? I think I would need to wait a bit, my guys tend to get that sibling rivalry thing going, and one up each other, where judgement goes out the window. I have to reign it in or someone hits the dirt. I've had to cover the bikes with xpel or hey would be roached. Regardless, that is one badass bike, nice work man. :thumbsup:


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## stom_m3 (Jun 28, 2011)

xc71 said:


> Looks great Stom! He's gonna love riding it.


XC71 thanks for the idea! I still go back to your thread for reference, ideas and weights.



Erock503 said:


> Man, that looks ridiculously cool! I've had no problem taking chances on the Chinese products for myself as long as they aren't knockoffs, but I've been hesitant for my little guys. This looks to be a product they market as their own though correct? That would really take a big chunk out of the weight, man that is tempting.
> 
> I take it your guy is very skilled though right? I think I would need to wait a bit, my guys tend to get that sibling rivalry thing going, and one up each other, where judgement goes out the window. I have to reign it in or someone hits the dirt. I've had to cover the bikes with xpel or hey would be roached. Regardless, that is one badass bike, nice work man. :thumbsup:


Thanks ERock! My boy has decent skills. He raced BMX bikes from 4-8 and I introduced him to mountain biking at 6. We used to hit the BMX racing scene quite a bit (up to 5 times a week) with various nationals sprinkled throughout the year. It's a lot of fun but a lot of work. Also, it was easy to do with the first child.

The ultimate goal was for me to be able to share the mountain biking experience with him. I think I've been able to accomplish that. At 6 years old, he was able to do Mammoth Skid Marks trail which is kind of nuts on a 20". It still amazes me how fast he can spin those cranks. His standard spin rate is 110-120 compared to mine of about 85-90. Always makes me feel like an ox riding next to him. 

My daughter unfortunately won't see the same level of racing as my son (plight of the younger) though not from a lack of interest from her but more of our busy schedules. But I'm still working on her and just got her riding my son's old modded Marin mountain bike. She's still not powerful enough to take on much past a graded fire road with mild up and down hills but she's getting there. She turns 6 in May so a little ahead of the curve on the mountain bike but without his bike handling skill at the same age.

I'll be able to trickle down the bikes to her so I don't mind spending the money.

That said, I just ordered the GT Speed 2pc cranks. I'll let you all know if they work which would be awesome to find a source for shorter cranks in 104BCD. I debated about getting 150 or 155mm. I went with the 155 knowing that it would be easier for me to just order 150mm if they were still too long. His Scott had 145mm so going to the 165mm XTs were a big jump. Unfortunately too big.


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## xc71 (Dec 24, 2008)

Stom, I see you are considering another seat. The SLR XP has worked out great for my son, he won't switch. It has decent padding and the weight isn't to bad @ 180 grams, reasonably priced. The rounded rear edge is really nice for not grabbing his shorts when hanging off the back on steep downhills. The both of us really like the SLR shape, so thats probably the biggest factor in comfort.


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## stom_m3 (Jun 28, 2011)

xc71 said:


> Stom, I see you are considering another seat. The SLR XP has worked out great for my son, he won't switch. It has decent padding and the weight isn't to bad @ 180 grams, reasonably priced. The rounded rear edge is really nice for not grabbing his shorts when hanging off the back on steep downhills. The both of us really like the SLR shape, so thats probably the biggest factor in comfort.


Thanks for the info. I moved his Scott saddle over to his new bike. I'll see if that works. If not, I may give it a try. Unfortunately we didn't get to ride this weekend as we went to the Happiest Place on Earth which can be the most frustrating place on earth...


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## stom_m3 (Jun 28, 2011)

So I rec'd the 155mm 2pc GT Cranks w/ 24mm spindle. The quality is only ok. Nothing great. It came with blue chainring bolts and bottom bracket. Supposedly it's made with an aluminum spindle per JR Bicycles website which saves an additional 30g's. I didn't stick a magnet to it to confirm it though. That said, the spindle width is designed around a BB92 bottom bracket. My bottom bracket is a BB95 but it still works.

I didn't take a picture of it but will later. The sprocket arms mount inboard of the chainring which could create clearance issues on some frames so be aware. Also, my chain line actually moved in about 1/2 gear width which was actually beneficial for the 11-42 setup.

That said, I ordered shorter 145mm cranks... Watching my sons cadence, he still needs shorter cranks. I'm ok with the trial an error effort on this one since he'll eventually move up to the longer cranks.

I also rec'd the FSA headset micro spacers and they work perfectly. They provide slightly more clearance for the top dust cover to frame head tube.

Here are the latest pics of the cranks;

XT Cranks, single w/bash weight @ 700g


GT AL Speed Cranks w/ RaceFace NW @ 621g


Close up installed


The bike as it sits now.


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## Trekkie8 (Jan 21, 2016)

Awesome bike:thumbsup:

Wish I was this handy:cryin:


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## stom_m3 (Jun 28, 2011)

Correction: The GT cranks do not come with an aluminum spindle. I just checked with a magnet. Of course, still a decent 2pc crank alternative in short lengths.


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## Steve-XtC (Feb 7, 2016)

I just shortened some following instructions from GrayJay

http://forums.mtbr.com/families-riding-kids/cannondale-24-race-21-speed-836355-5.html#post12473027

Not perfect (didn't quite get the hole dead centre) but they will certainly work! 
Really not that hard as I thought.

I measured up and dot punched then piloted with a 5mm drill. Very slowly or it melts the alloy. Then did a 9mm and then a 13mm (which is practically the correct size for 9/16 tap). Just used my rechargable drill which can just take 13mm.

I made a jig out of 18mm plywood ... put a bolt through the crank (right through the wood) then screwed two extra bits left and right of the crank which were just thinner than the crank and then for good measure stuck a piece of thinner ply across the top and just screwed it down.

I'm waiting on the pedal taps so didn't tap them yet but I did ask a friend who is a toolmaker and he says they are more than OK for tapping. (There are 1-2 scratches inside the drilled part)

Cutting I used a cheap mitre saw with PCT blade.. then filed the ends. (I could file more but got bored)

UPDATE: Cranks finished, fitted and working great! 
Really easy .... thanks to GrayJay ....


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## stom_m3 (Jun 28, 2011)

Went with a quick ride with my son today after work. Swapped out the cranks from the 155mm to 145mm. He's a lot more comfortable on them and the loss in leverage doesn't seem to affect him. I'm currently running his tubeless at 18psi but could probably drop it a little more. That said, he hasn't complained about traction. I bumped the Rockshox up 5psi to 65psi to absorb some of the bigger hits.


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## Steve-XtC (Feb 7, 2016)

stom_m3 said:


> Went with a quick ride with my son today after work. Swapped out the cranks from the 155mm to 145mm. He's a lot more comfortable on them and the loss in leverage doesn't seem to affect him.


Crank length on pre-built kids bikes is ridiculous. Given your experience I'm wondering if I shouldn't have gone shorter than the 142.5mm as my kid JUST fits on his 24er.

(I'm 5'10-5'11 and starting to question if I shouldn't at least try 170mm cranks based on my experience and others like you. )


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## stom_m3 (Jun 28, 2011)

Steve-XtC said:


> Crank length on pre-built kids bikes is ridiculous. Given your experience I'm wondering if I shouldn't have gone shorter than the 142.5mm as my kid JUST fits on his 24er.
> 
> (I'm 5'10-5'11 and starting to question if I shouldn't at least try 170mm cranks based on my experience and others like you. )


It's funny that you said that because I was thinking the exact same thing.

When I first built his bike up with 165mm cranks, I was surprised at how fast my cadence was on his bike. I could spin at a fairly high rate with no problems. I've always taken for granted that at 5' 8" I fit 175mm cranks since that's what typically comes on medium sized frames. But I could probably drop from 175mm to 170mm and help my efficiency and cadence with very little loss in leverage. I'm so used to tinkering with my son's fit that I never take into account my fit, especially crank length. Hmmm something else to go buy... Thanks.


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## Steve-XtC (Feb 7, 2016)

stom_m3 said:


> It's funny that you said that because I was thinking the exact same thing.
> 
> When I first built his bike up with 165mm cranks, I was surprised at how fast my cadence was on his bike. I could spin at a fairly high rate with no problems. I've always taken for granted that at 5' 8" I fit 175mm cranks since that's what typically comes on medium sized frames. But I could probably drop from 175mm to 170mm and help my efficiency and cadence with very little loss in leverage. I'm so used to tinkering with my son's fit that I never take into account my fit, especially crank length. Hmmm something else to go buy... Thanks.


I might pump up the shocks and tires on my kids and give it a go ....
Like you and I believe 95% of the cycling community I just assumed ... never gave crank length a thought. It's not like its an easy thing to just try... like swapping a stem or saddle.


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## neilether (Sep 10, 2007)

Resurrecting a slightly old thread here, but I'm in the last moments before purchasing a chinese carbon frame for my son. 

I did find that SRAM makes a 155mm crank in their NX and GX groups, but they are a 1x only 94 BCD. 

Canfield Brothers makes a 155mm length in a 1x only direct mount (which is nice because you could put as small as a 26t chainring on there)

The GT seems like an interesting option. Where did you purchase those and which model is it? My frame will be a BB92 and 24mm spindle as well.


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## stom_m3 (Jun 28, 2011)

neilether said:


> Resurrecting a slightly old thread here, but I'm in the last moments before purchasing a chinese carbon frame for my son.
> 
> I did find that SRAM makes a 155mm crank in their NX and GX groups, but they are a 1x only 94 BCD.
> 
> ...


Cool! Which frame are you going with? I purchased the GT cranks from JR Bicycles.


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## neilether (Sep 10, 2007)

Most likely this frame:

Excellent quality! 2014 CUBE carbon bike frame mtb,bike frame mtb color green/black size 14'/16' bicycle frame.-in Bicycle Frame from Sports & Entertainment on Aliexpress.com | Alibaba Group

It looks like I can get this from amazon, ebay, or alibaba. I'll have to look up those GT cranks. I've never heard or JR bicycles. Do they have an online presence?


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## stom_m3 (Jun 28, 2011)

neilether said:


> Most likely this frame:
> 
> Excellent quality! 2014 CUBE carbon bike frame mtb,bike frame mtb color green/black size 14'/16' bicycle frame.-in Bicycle Frame from Sports & Entertainment on Aliexpress.com | Alibaba Group
> 
> It looks like I can get this from amazon, ebay, or alibaba. I'll have to look up those GT cranks. I've never heard or JR bicycles. Do they have an online presence?


Yes, both JR bicycles and Dan's Comp have a large online presence but geared towards the BMX community which is how I'm familiar with them.

Cool looking frame. Good luck. Be sure to post your build.


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## neilether (Sep 10, 2007)

Yeah. Will do. The crank is the most vexing part with that BB92 frame. However, from what I understand (which is admittedly very little) that BB actually allows a standard 24mm spindle, 2-piece crank to be used. These are the cranks typically associated with the 68/73mm outboard bearing BBs right?

At least that's what I've been assuming.....

I'm currently leaning toward the Canfield, because I can use Direct Mount SRAM rings as low as 26t. Of course, the 2x crank would allow for much larger gear range.


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## stom_m3 (Jun 28, 2011)

neilether said:


> Yeah. Will do. The crank is the most vexing part with that BB92 frame. However, from what I understand (which is admittedly very little) that BB actually allows a standard 24mm spindle, 2-piece crank to be used. These are the cranks typically associated with the 68/73mm outboard bearing BBs right?
> 
> At least that's what I've been assuming.....
> 
> I'm currently leaning toward the Canfield, because I can use Direct Mount SRAM rings as low as 26t. Of course, the 2x crank would allow for much larger gear range.


You are correct. The spindle is short, such that the crank splines sit on the bearing surface. Not ideal but there was no better solution for a shorter crank. If you have a BB92 spindle length available, by all means get that.

As for the 1x setup, I recommend it. Simple, light, and plenty of gear range.


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## neilether (Sep 10, 2007)

I pulled the trigger. A 14.5" frame will be in my hands in 7-74 days, or however long it takes.....

Build so far:

-155mm Canfield Brothers crank which I'm excited about (28t ring for now). 
-Older Fox 32 Fork. 
-Sram X9 1x10 drivetrain.
-40mm stem
-cheapo wheels I had laying around

Just need to decide on brakes and pick up a few other random bits. My son caught me talking about the build with one of my buddies, so it won't be a surprise anymore, but he's stoked. It'll be fun to get it built up.


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## neilether (Sep 10, 2007)

I am very strongly considering these brakes:

Clarks M2 MTB Hydraulic Disc Brake Set 850 1700mm Black Includes Rotors | eBay

They get good reviews on Chain Reaction Cycles, and they are dirt cheap. Plus, they use Shimano style pads and mineral oil. THey look exactly like some of the lower end Shimano brakes, so I assume the bleed procedure is similar.


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## neilether (Sep 10, 2007)

Just waiting "patiently" for the frame to arrive. I have most everything else ready to go. Patience is not my strong suit.....


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## neilether (Sep 10, 2007)

Frame is here! Build will commence tonight. Is it bad that I may, in fact, be jealous of my son's bike?


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## stom_m3 (Jun 28, 2011)

neilether said:


> Frame is here! Build will commence tonight. Is it bad that I may, in fact, be jealous of my son's bike?


Pictures please!


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## neilether (Sep 10, 2007)

stom_m3 said:


> Pictures please!


Will do. I almost feel bad putting on the heavy 26" wheelset that I have laying around. That will make a decent upgrade in the future.


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## neilether (Sep 10, 2007)

The build begins!


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## jestep (Jul 23, 2004)

neilether said:


> Frame is here! Build will commence tonight. Is it bad that I may, in fact, be jealous of my son's bike?


Lowered setback seatpost and throw it around like a large BMX bike...


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## neilether (Sep 10, 2007)

All in all, I am very satisfied with this frame. I do have two gripes/watch outs for any potential buyers that I will go over in a bit.

The built up bike is 23.25 lbs. This is with a heavy, old wheelset, AM/DH cranks, and a heavy cheap cassette. No fancy carbon fiber bits or anything like that. My guesstimated build cost is ~$800. This is a full 8lbs lighter than his current 24" bike. I"m very happy about that.

Sorry for the crappy low light cell phone pic, but I'll get more when I can if people are interested.









Complaints:
1. This could just be an issue with the supplied headset, but the upper bearing was too short. So the upper headset cap would compress down on the headtube itself, rather than the bearing. I had to add ~1.5mm of headset spacers on top of the bearing. This way everything tightens up properly.

2. The seatube does not allow for much seatpost. There is a riveted cable stop for a front derailleur and those rivets protrude into the seat tube. I'm fairly certain that is what is stopping the seatpost from dropping in farther. I may drill out those rivets and see if that helps. HOwever, it appears that there may be a narrowing of the diameter near that point as well. ULtimately, there is very little height adjustment possible in the seatpost. By the time you get the minimum insertion depth in the frame, there is probably only an additional 1 to 1.5" of adjustment. He's growing like a weed, so I'll probably just have to get another seatpost and cut it to length when he gets taller.

Neither of these issues are deal breakers by any means. Just something to be aware of for potential buyers.


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## neilether (Sep 10, 2007)

Oh yeah, one more little complaint. On this frame, the water bottle bosses are placed extremely high on the downtube. Makes it difficult to fit a full size water bottle in. If the bosses were shifted one hole down (and there's plenty of room) it would have made a lot more sense.

Anyway, my kid loves it. Mission accomplished.


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## stom_m3 (Jun 28, 2011)

neilether said:


> Oh yeah, one more little complaint. On this frame, the water bottle bosses are placed extremely high on the downtube. Makes it difficult to fit a full size water bottle in. If the bosses were shifted one hole down (and there's plenty of room) it would have made a lot more sense.
> 
> Anyway, my kid loves it. Mission accomplished.


Camelbak mini mule solves that issue.


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## BullSCit (Mar 26, 2004)

neilether said:


> All in all, I am very satisfied with this frame. I do have two gripes/watch outs for any potential buyers that I will go over in a bit.
> 
> The built up bike is 23.25 lbs. This is with a heavy, old wheelset, AM/DH cranks, and a heavy cheap cassette. No fancy carbon fiber bits or anything like that. My guesstimated build cost is ~$800. This is a full 8lbs lighter than his current 24" bike. I"m very happy about that.
> 
> ...


I'm about ready to order this frame too for my daughter, thanks for all the info. Was wondering if you ever found a way to get the seatpost lower. I could buy several seatposts and cut them for the height she needs at the time, but would rather not have to do that. Any other issues that you have found after getting it out on the trails?

Thanks - BS


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## neilether (Sep 10, 2007)

BullSCit said:


> I'm about ready to order this frame too for my daughter, thanks for all the info. Was wondering if you ever found a way to get the seatpost lower. I could buy several seatposts and cut them for the height she needs at the time, but would rather not have to do that. Any other issues that you have found after getting it out on the trails?
> 
> Thanks - BS


I have not found a solution. I cut off the current seatpost so it'll work, but it doesn't allow much adjustment.

I may drill out the rivets holding on that front derailleur cable guide/stop, but I'm not entirely sure that will solve the problem. It appears that the seat tube itself necks down a bit at that junction as well, though I haven't thrown my calipers on it to verify.

That being said, he LOVES this bike. I just figured that seatposts are cheap, so I'll just have to buy a couple and cut them to length as he grows.


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## bendermike (Oct 17, 2011)

Just finished a build for my 10yr old, great insights on this thread helped out tremendously. Of course it dumped 4" of rain the day it was done so no trails yet just around the neighborhood but he loves it. 

















Sent from my iPad using Tapatalk


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## bendermike (Oct 17, 2011)

Just finished a build for my 10yr old, great insights on this thread helped out tremendously. Of course it dumped 4" of rain the day it was done so no trails yet just around the neighborhood but he loves it. 


















Sent from my iPad using Tapatalk


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## bendermike (Oct 17, 2011)

Just finished a build for my 10yr old, great insights on this thread helped out tremendously. Of course it dumped 4" of rain the day it was done so no trails yet just around the neighborhood but he loves it.















Sent from my iPad using Tapatalk


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## bendermike (Oct 17, 2011)

Sorry for the multiple posts, operator error.


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## dusoo (May 4, 2017)

stom_m3 said:


> I'm currently running his tubeless at 18psi but could probably drop it a little more.


Hi stom, which tubeless tyres and rims did you go with? Thanks


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## stom_m3 (Jun 28, 2011)

The wheels are the Sun Ringle Black Flag Pro, Stan's sealant, Specialized S-Works Fast Trak front and rear. The tire pressure seems to work well for him still. He's now 90lbs. No flats, no burps. 

As for my opinion on the components, the Black Flag Pro wheels are ok but the hubs can loosen causing mis-shifts. The SL version which I bought for myself, the bladed spokes lose tension easily, along with the hub. Love the Stan's. The Specialized tires inflate onto rims easily.

The 26" deals are getting less and less but there still out there if you look.


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## neilether (Sep 10, 2007)

I forgot to follow up on this, but here is my son's bike in action:


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## stom_m3 (Jun 28, 2011)

Neil - The pic didn't show up. Would love to see it though.


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## neilether (Sep 10, 2007)

stom_m3 said:


> Neil - The pic didn't show up. Would love to see it though.


Hmmm. It shows up on my screen....

I've attached it here just in case.


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