Makeing a 16" Hotrock "bigger" with an 18" or 20" fork?- Mtbr.com
Results 1 to 8 of 8
  1. #1
    mtbr member
    Reputation:
    Join Date
    Dec 2018
    Posts
    7

    Makeing a 16" Hotrock "bigger" with an 18" or 20" fork?

    I picked up 16" Specialized HotRock for my son. He's about 48" tall and rides a 16" TykesBykes push bike pretty well. We have a 20" steel Trek Mountain Lion that seems to big and is definitely way to heavy for him to handle.

    The Hot Rock actually seems to fit a bit smaller than the push bike and I'd like to make the fit "bigger" I did a little research on this forum and a number of people have swapped in 18 or 20 inch forks onto the 16" frame.

    So the question is whether this is a good idea for a first pedal bike? Or should I just keep looking for a lightweight 18" bike?

    The other changes I'm looking at include a new seat and a setback post, longer cranks and reduced gearing.

    Any feedback would be appreciated. Thanks, Woody Sr.

  2. #2
    mtbr member
    Reputation:
    Join Date
    Jun 2019
    Posts
    171
    My daughter was a short 44" height at 6 years old when we put her on a 20" bike. She has been OK with it although the reach is a little long for her, but she got use to it. She was never on a push bike, she learned on a 16" pedal bike after a year with training wheels.

    To me a 16" bike is too small for a 48" kid unless your son is very young but tall. I suspect that after he learns to pedal while balancing, it will nearly immediatey be too small for riding around.

    We paid $100 for a used 20" Cannondale Quick 20 (about 22 lbs), and I have seen them advertised for less, so I personally would not spend any money on a 16" bike when it is possible to buy used and decent and cheap relatively easily.

  3. #3
    mtbr member
    Reputation:
    Join Date
    Dec 2018
    Posts
    7
    I am keeping an eye out for a lighter 18" or 20" bike, and I'm not going to sink a lot of time and money into the 16" HotRock, which I picked I picked up for $25. I'm hoping to find a fork at the co-op, and I'm pretty sure I have every thing else in the parts pile, including a longer set of cranks.

  4. #4
    mtbr member
    Reputation: Darth Lefty's Avatar
    Join Date
    Sep 2014
    Posts
    1,394
    Iím not understanding how this would be an improvement

  5. #5
    mtbr member
    Reputation:
    Join Date
    Nov 2011
    Posts
    600
    Things I'd say:
    - Don't bother with longer cranks -- going longer is more likely to have drawbacks than benefits. My son has been fine with purposefully keeping him a size down from "normal" for cranks.

    - The gearing change probably won't be worthwhile -- at his height, getting him on a 20" with gears is the way to go if you want to go off-road.

    - If you're looking at a seatpost / saddle, look for a pivotal saddle with a low stack height. The difference in height can be almost as much as the difference between a 18" and a 20".

    - Any 20" suspension forks you'll find at a local co-op are likely to be heavy coil forks that will be heavy and not have much benefit.

    - Raising the front end up with a longer fork will also bring the bars closer -- not exactly the effect you want. It would be a lot easier to just look for taller riser bars at the co-op and just go with more of a BMX fit. (as an added plus, if he's mostly standing and riding on it, you may be able to avoid changes to the seatpost / saddle)

  6. #6
    mtbr member
    Reputation:
    Join Date
    Dec 2018
    Posts
    7
    RE:
    Quote Originally Posted by TimTucker View Post
    Things I'd say:
    Im not familiar with what "a pivotal saddle with a low stack height" is.

    As far as forks I was going to look for a ridged fork. MK2 eyeball thinks that the original fork is bent back a bit so I'm not just looking for cool points on the fork swap.
    I had thought about the bars coming back a bit, so I will get some measurements before and after and see if I need a little longer stem.

    We have another steel junker 16" bike that has longer cranks, but fits smaller than the Specialized. My son rode that with training wheels for a while, but that was a constant haul ass and crash experience so we went back to the push bike. So I'm planning on shifting these cranks over.

  7. #7
    mtbr member
    Reputation:
    Join Date
    Nov 2011
    Posts
    600
    Stack height is just the distance from the top of the seatpost to the top of the saddle. The lower the stack height, the closer to the ground the saddle height will be when it's fully inserted in the seat tube.

    Pivotal saddles use a different seatpost interface than railed saddles -- because of the way that they mount, the end result is you can have a 20" bike with a saddle height close to the traditional saddle height on many 16" bikes.

    Spawn uses them on their bikes:
    https://spawncycles.com/yoji-16

    Here's what I have on my son's bike at the moment -- it comes down just as low as the thinner Spawn saddles:
    https://www.tiogausa.com/d-spyder-pivotal-s-spec.html


    What about the fork on the Trek you already have? Could you try that out just to get an idea of fit?

    Biggest practical issue with the longer fork is that you'll lose the front brakes (assuming it's one of the hotrock models that has them).

  8. #8
    mtbr member
    Reputation:
    Join Date
    Dec 2018
    Posts
    7
    The Trek fork is 1" threaded and the Hotrock is 1 1/8 thread-less. The Hotrock is also a coaster brake bike. There's a fair chance I will find a light weight 20" bike before I take the 16" bike apart, but I do think that a lighter slightly undersized bike will be better for getting to where pedaling will click, as we've got a pretty good start on control with the 16" push bike.

Similar Threads

  1. 20/18's or 18/16's?
    By finch2 in forum Singlespeed
    Replies: 12
    Last Post: 07-10-2014, 01:25 AM
  2. Updating a 2007 Hotrock 24 and 2003 Hotrock 20?
    By TheNormsk in forum Families and Riding with Kids
    Replies: 10
    Last Post: 01-04-2012, 03:36 PM
  3. FOX VAN R 07 -- Makeing very strange noises???
    By DH/FR-CHRIS in forum Shocks and Suspension
    Replies: 2
    Last Post: 07-21-2008, 03:35 PM
  4. sick crash video and makeing it.
    By Stevirey in forum Downhill - Freeride
    Replies: 9
    Last Post: 02-06-2006, 11:01 PM
  5. Totally OT, started makeing a guitar today...
    By Jisch in forum Riding Passion
    Replies: 33
    Last Post: 03-18-2004, 06:14 PM

Members who have read this thread: 34

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

THE SITE

ABOUT MTBR

VISIT US AT

© Copyright 2020 VerticalScope Inc. All rights reserved.