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  1. #1
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    When to size lightweight rider up from 16" to 20"?

    My son was on a Giant Pre from 18 months to 3 years when he switched to a Spawn Yoji 16". I should have started with a 14" as he regressed quite a bit. The last year (4.5-5.5) he has looked really confident on the Yoji, but I finally took him for some real MTB and the 16" wheels don't have enough roll over (or suspension...). He mostly rides the Yoji like a DJ at skateparks, but I imagine that will change in the next few years.

    He's about 50-60th percentile for height, but consistently 10th for weight.

    At 44" tall with a 19" inseam he meets the Spawn 20" minimum size chart. But the Yoji is 13 lbs, so about a third of his 37 lbs body weight. The 20" hard tail Spawn is 22lbs IIRC, which is like 60% of his body weight. He won't reach a 1:3 bike:body weight ratio for that bike, based on the CDC growth chart, until he is 11, by which he'll be way too tall obviously.

    Only time I've ever ridden something that heavy in comparison to me, it was rolling dirt bikes down hills where the engine wouldn't restart, and it sucks.

  2. #2
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    He'll be fine on the Spawn 20" if he is a decent rider. You are right on the weight but their isn't much you can do unless you go rigid with carbon forks or drop a TON of cash on something super light.

    Rollover does suck on 16" wheels but whatever, he'll gain great skills by going a bit slower and learning to deal with it instead of just rolling over it.

    Regardless, you are going to have to get a 20" at some point. Fwiw Prevelo makes a new hard tail now. I'm not a fan of the looks but I do like 67d HTA instead of Spawns 68. Its important to have a slacker HTA on a Hardtail as under sag it gets steeper quick unlike a FS bike. Not sure about their spec and other stuff but its a nice bike too.

    Those frames are great starting places. You can buy it and then start to upgrade if needed to drop weight.

    NOW, that being said, you could just get the Trail Craft 20" too...its lighter but more money. Probably exactly what you are looking for. 19lbs with everything on it. The suspension is pretty sick (same as Spawn, Lil Shredder). I bet Brian at Lil Shredder could also dial you into something ultra light too.

  3. #3
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    We'll stick with the 16" for now, but I figure by next summer he'll be on something else, at least for trails. We've run into a couple really good riders at skateparks who are the same height, and they are on 12" and 14".

    I have to start to prepare the wife for the price tag; I'm not scared because I know how much my own bike cost She was a bit miffed at $400 for the Yoji, but given the number of hours he has spent on the bike, it's cheap as entertainment goes.

    The Trail Craft looks good, hadn't seen that before. $600 to shave 3 pounds though, heh... The Lil Shredder is $2250, and I don't see a weight listed. We'll be driving through Troutdale in February tho, so maybe I'll see if I can drop by.

    I thought the Spawn HT was 66 degree? I just emailed them to ask...

  4. #4
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    We were in a similar boat here, with a tall 3.5yo trying to decide the next step up from a 14" Yoji. His seat is at 18" right now with feet able to touch the ground somewhat easily.

    I ordered a 16" Yoji, but am adding a 20" Suntour air fork with a new 16" front wheel built up for front disc brakes to make it easier to ride over things on the local trails.

    Having measured, the A2C measurement with no sag on the Suntour is about 100mm longer than stock fork, but the stock bars are about 100mm higher than a flat bar, so it should wind up with similar reach, but slacker HA.

    In theory you could do something similar with an 18" or 20" wheel up front as well (20" might be make it easier to find disc wheels. but would have a much bigger effect on the geometry).

    Rim came in today & hub came in yesterday, so I'll be heading over to the local BMX shop soon to see about having them build up the wheel.

    Here's what I've ordered so far -- once everything is together I'll post a thread with photos and more details:

    Fork - Suntour XCM HLO AIR SL 20 (1780g uncut):
    https://www.srsuntour.us/products/xc...=5280456572959

    Brake - TRP Spyke Mechanical Disc (169g):
    https://www.ebay.com/itm/TRP-SPYKE-M...R/202475414458

    Rotor - Lightweight (68g):
    https://www.aliexpress.com/item/68g-...887975517.html

    Rim - Kinlin 305 double wall (180g):
    https://www.aliexpress.com/item/Free...051321134.html

    Hub - Circus Monkey HDW2 (119g):
    https://www.ebay.com/itm/253961531886

    QR Skewer - Titanium hex bolt (??g for just the front, 35g for pair):
    https://www.aliexpress.com/item/1-Pa...851247608.html

    Bars - ControlTech SUP 28A (155g uncut):
    https://www.amazon.com/Control-Tech-.../dp/B00BV3YL32

    Stem - Wren 50mm (74g):
    https://wrensports.com/product/crazy...aluminum-stem/

  5. #5
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    My son is about the same height and a little heavier (about 43" and 40lbs). He was on a modded 14" commencal ramones and I just put him on a 24/20" mixer I built. We live on the side of a mountain and our local trails are steep and involve about 2' climb top to bottom, so weight was super critical. I got his bike down to 16lbs. I think the ideal is to go with the biggest wheels he can physically fit, but keep the weight down. Kids bikes aren't any cheaper to build light than adult bikes for the most part (rims and frames are cheaper, the rest is all basically the same).

  6. #6
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    Hey BikePilot1, what parts did you use? What was the frame?

  7. #7
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    Here's the Prevelo Zulu 3
    https://prevelobikes.com/products/zulu-three

    22.2 lbs

    Hmm all the Alexrims which I have encountered have been c#$@.

  8. #8
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    Quote Originally Posted by fitek View Post
    Hey BikePilot1, what parts did you use? What was the frame?
    I've got full thread on it with all the details. I'll bump it up.

    Sent from my Pixel 2 using Tapatalk

  9. #9
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    URL is https://forums.mtbr.com/families-rid...d-1092907.html
    For the record.

    Will have to digest this over the weekend

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