Help me spec a bike for my son

[jwilds1]

Okay, I know I've posted about building a bike for my son, but I'm getting more serious now and could use the collective help of you guys here.

I'm having difficulty finding a frame.  Peter sent me the geometry of the CS-016 in 14.5" and I wasn't enthused with the long reach (560mm ETT).  I found the following frame - http://www.ebay.com/itm/261539901827?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT - and the geometry looks a million times better, but only comes with a BB92 (press-fit).

For simplicity's sake, I was going to go with a 1x setup and mechanical disc brakes.  His current 24" wheel bike has 150mm cranks, and I expect him to grow another couple of inches between now and the start of next season, so I was going to go ahead and make the leap to 170mm cranks.

I fully realize the frame, fork, and wheels are likely sunk costs as he'll outgrow most of them in a few years, but I'm willing to eat that.  What I need help on is frame options - do you guys know of any other small/xsmall (14-16" frames) in 26er?

[MTB2223]

How tall is your son ?

This year I bought a 14"alu frame (26-er) for my 7-yr son. The frame cost me less than 90 dollar for a original cube frame. Had thoughts of buying him a carbon frame, but hey, he is still a young kid, he's falling, he's learning. It's his bike for the training and races, not to play with around the neighborhood. He's already more technical than his 11-yr sister (national champ in the Netherlands).

It's important to have a frame/bike which it not to big for your son. It's better to have one size smaller than one to big. Smaller bike is easier to handle and better to learn good technics. Good handling is more fun. And fun is the most important factor of biking for kids.

[bxcc]

The Dashine eBay frame is the smallest I've seen. I wouldn't worry too much about the BB92 shell. Sram makes a BB92 bottom bracket that works with their GXP cranks. Just google bb92 bsa adapter and some other options come up too. Race Face makes one too and Jenson USA has some decent prices in RF Cranks right now. A few under $100. If he is outgrowing his 24" bike, you could check the geo numbers on some small 27.5 frames. You can run 26" wheels to help standover height or save money if you already have a set to use. Same with the fork.

[jwilds1]

Right now, he's 4'8", and I'm guessing he'll add another inch or two in the next 6-8 months.  I am also looking into aluminum, but I'm turning into a weight weenie

As for the BB92, I do not fear it, but if given the choice I'd rather stick with a BB30 or similar.  I did find the RaceFace Cinch setup (BB92, 30mm shaft), and 170mm cranks.  I can also go all the way down to a 26T drive - I have to do the math if I end up going 1x9, 1x10, or 1x11.  If I end up with 1x11, he's going to have a better drivetrain than me

That's a good idea on the 27.5 with 26 wheels - never really thought of that.  Any downside?

[bxcc]

No down side that he would notice. The BB would be lower but coming from a 24" wheeled bike it will still be higher. I bought my 8 year old daughter who is 4'6" and all legs, a GT Avalanche in XS. It is a bit of a stretch for her but she would go between the new and the old bikes depending on what terrain we were riding. A handful of days on the new bike on bike path terrain made the transition better. The cranks are 170 and realistically they should be shorter. Probably 160 or so. I may try to shorten them this winter. Also, I rolled the handlebars back a bit to help with the reach. She is borderline fitting but she is now riding it like a champ and doesn't want to ride her old bike anymore. I let her decide on which bike to take. Here is the geo of her bike now and you can compare some of the measurements.

http://www.bikesdirect.com/products/gt/images/gtw_avalanche_3.gif

For what it's worth, the GT came with a 3x9 and a 11-36 Sunrace cassette and I swapped the 3 rings for one RF N/W 32t ring in purple and it seems like a great gear combo for her. But we don't have a crap ton of climbing where we ride either.

[jwilds1]

Can someone help me out with this whole BB92/BB30?  If I were to go with the eBay frame above, I assume I can throw on a set of Shimano cranks that work with BB30 and call it good?

I just now figured out that the XT double crankset comes in 165mm and you can get it 40/28 down to 36/22.  I may keep it a double, but may try a single (take off big ring, replace with bash guard).  Also, any issue using 10-speed chain on a 9-speed rear cassette?  I am going to try and avoid the m8000 XT stuff and go M785.

[bxcc]

As long as you get the appropriate BB or adapter you should be fine. No idea on the 9 spd / 10 spd cross compatibility.

[nick_n_ii]

I'm currently specing a bike build for my 12 yr. son. He's 5'2". So I know what your going threw in trying to get the most for your kid.

I'm looking at the CS-016
http://www.xmcarbonspeed.com/Productinfo.asp?f=1390

[jwilds1]

Bumping an old topic..

I looked at the CS-016, and it has what I think to be a really long reach.  Peter sent me the geometry.

I'm looking at this one - http://www.ebay.com/itm/White-painting-26er-carbon-fiber-mountain-bike-frames-with-headest-and-BB92-OEM/251755013728?_trksid=p2045573.c100033.m2042&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20131017132637%26meid%3Dc719d72a0fef4cc5818d52ab7a0287e0%26pid%3D100033%26rk%3D3%26rkt%3D4%26sd%3D381487977309

Only thing I can think of negative would be the BB92.  Anybody else find anything I should worry about?

[bxcc]

I've looked at that one in the past too. How tall is the rider?

[Jmh]

I found this thread quite useful,  just looking at building a bike for my 11 year old.  In the end I found this http://www.rczbikeshop.com/default/rcz-2015-frame-junior-race-27-5-disc-matt-black-red-size-14.html#

Just the size I was looking for and not too heavy either. A full carbon can wait a couple of years till he grows out of this.

Detail from the site for anyone interested;

For 27.5" fork and wheels
Fork travel: 80 to 105 mm
Construction: AL7005, triple butted, hydroformed tubes
The rear bent offers more comfort
The top tube/rear stay intersection is designed to ensure the optimum weight distribution
The Tapered headtube offers more reliability and rigidity

Specifications:
Travel: 80-105mm
Seatpost diameter: 27.2mm,
Front derailleur: 31.8mm
Headset compatible: Semi-integrated 1.5>1 1/8 Tapered (Ø44/56mm)
Bottom bracket: BSC 68mm
Brake: Disc IS
Rear axle: 9x135mm

White with Red stickers

 Derailleur hangers are delivered with the frame, disassembled and packed in the parcel.

5 years warranty

GEOMETRY:

Seat tube   Top tube effective   Chainstay   Headtube   Seat angle   Head angle
355mm   528mm   430mm   120mm   73°   68°

Cheers

Jmh