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  1. #1
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    New question here. Quick ? - Crank arm length for girls first 26"

    I got a 15" Schwinn Moab HT / Vbrake type frame for 26" and headset, stem handlebar and Judy fork free (was left by dumpster by the bike shop!) and picked it up years ago. Now my daughter is 12 and big enough to use it, so I am building it up for her. We don't live near mountains and V brakes will be fine. For budget build and lots of range I am going 3x8, which is the type of hub was on the rear wheel I was given in exchange for a 6 pack.

    Question is, I noticed some small bike frames are spec'd with 170mm cranks, is that recommended for small frame 26"? I tried checking a few bike mfg. bikes to see what they did but the specs for crank arms are not typically listed.

    Also, this is a budget build, does anyone recommend a crank? The existing square axle BB works but needs cleaning out and regreasing.

    Amazon has the Alivio M410 22x32x42t 170mm for about $40 but wondering if I am going to regret it later.

    The kids ride some but not a ton right now - we don't have close by trails yet. I have a $2k Trance X I just built last year FYI. Just saying as spending a bit of cash on bikes is a possibility, and I do have a younger daughter that can use it even if #1 out grows it.

  2. #2
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    You need to find a cheap parts donor bike, that will end up the most expensive free bike you've ever owned if you build it up piece by piece! My son is a very tall 9 year old, I found him a 13" Klein Pulse Comp 26er for $100 on craigslist (admitedly a great buy, but probably a $250 bike on a good day). I think many of the smaller frames come with 170mm cranks, the 170s on the Klein seem fine for him. My old race mtb has 180s, my current/modern bike has 175s, my road bike has 172.5s. I imagine she'd be fine with 170s, I doubt you could find anything good smaller than a 175.

  3. #3
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    have you tried looking up the oem specs for the frame in question?

  4. #4
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    OK I probably did not include all the information. I am a packrat and I had already a set of Avid SD V brakes, a front wheel, someone gave me a rear wheel, I got a seatpost (via looking up bike specs on line for size) from Ebay for like $12, It has a BB. A guy also gave me a crankset with the wheel for some beer but its damaged upon closer inspection that was disappointing as that typically can be a big $ item typically, but the $30 one looks reasonable. I got some grip shifts for shezmano for $19, all I need is a front/rear derail. I have spare chains and tires and a bucket of flat pedals, old computers, even grips, etc.

    I got her last bike on craigs, a Marin 24" for $100 that was a steal, it still had nubs on the tires and had probably less than 10 miles on it. I guess I could look for a donor bike but what fun is that, plus sizes can be different and my wife would shoot me if I brought in another bike. My LR is already looking like a bike shop with two trees and a work stand & tools (LOL).

    One thing that intrigued me was how light action the Judy is, it will suit her 75lb really well, most bikes for low end have such a stiff fork they don't do much. I have not rebuilt the judy yet - had some other projects in front, but daughter's birthday is approaching very rapidly!

    Its also a fun father/daughter project and I have had her doing the work, that is a priceless lesson. Her last Marin she likes a lot but has no idea how it works and how to tune it.

    I was thinking the 170 would be a good size, but figured easier to ask.

    Thanks for your time and advice.

  5. #5
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    Quick ? - Crank arm length for girls first 26"

    Personally, how tall now, inseam and 'stride' length would make a difference for perfection. But with the information you've given and making general assumptions, yes 170's should be fine.

    Joe

    Note - the bike I built up last year for my 5'-6" wife has 170's on it and she's just fine with them.
    '01 GT Aggressor 2.0
    '97 Jamis Dakota (CrMo)
    C-dale Pro Comp - Road

    Why am I on the computer and not riding???

  6. #6
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    Wink

    Thanks ordered 170mm, and some F & R 8 spd derailures to go with the shifters. I"m going 22-32-42 front and 11-32 rear which should do her for about anything we are riding. The stem is a bit long for someone barely big enough for the frame...Have to sort through my parts bin..or maybe add that to the shopping list...(bike building...does it ever really stop?) LOL

    I really want to get her sister who is bigger for age (8) up on her 24" Marin and off the dept store 20" mtn bike she is riding...it has 5 speeds and a spring fork of some description but is cheese metal china variety ... now its too small for her so that is driving the project...Along with older sister's Birthday next week!

  7. #7
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    My 12 year old rides the wifes 17" Hardrock these days with 175mm deore crank the entire drive train was put together out stuff I had knocking about - she is a bout 5' 3" - it's a little large for her as yet but she can handle it OK. 170's will be fine
    The 13" Hotrocks 24" is too small for her and the 9 year old has taken it over. thjat has 165mm cranks on it.

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