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  1. #26
    jr2
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    Way to go Rondo! Now keep us apprised of your changes and take care of yourself after all the wonderful luck you've been having!!

  2. #27
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    Got the crank arm puller tool in the mail and removed the arms without any problems! One of the best tools I've ever bought!

    Now to get the BB out. Drive side came off with no problem. Could have even used a Crescent wrench! The left side had that nasty looking oval threaded cup with the two flat spots. This thing is rusted in place and it's time to buy another tool I guess. For those wondering I did a little mic'ing and internet searching and found I need a Park Tool HCW-15 36mm wrench. Must have called 25+ bike shops in SoCal and no one carries it.

    Here we wait again for the mail. In the meantime I think I'll go outside and install some quick disconnects on the sway bar for my Jeep.

    Btw. the front Zoom fork shocks for 20" wheel seem quite heavy and I'm looking for some simple straight forks with v-brakes to replace and lighten up the front end a little. I'm open for suggestions if anyone knows where I can find some? All I'm finding on ebay is either too short ,or for center-pull ot side pull brakes.

    I have a pair I could use but not sure the geometry is right. The Zooms measure from axle to first bearing 14" but the straight pair I have measure from axle to first bearing 12". A 2" difference. Not sure if that is going to fly.

    Thoughts?

  3. #28
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    I'll measure the Mozo I just took off my daughters bike against the rigid I put on...

  4. #29
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    Mozo suspension - 13 1/4in
    Rigid - 10 3/4in

    Big difference but I felt the 3+ lb difference worth it.


  5. #30
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    Cool! Maybe I'll give it a shot!

    Thanks for posting that!

    Hopefully my wrench comes tomorrow.




    Btw: What fork is that?

  6. #31
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    Quote Originally Posted by Rondo View Post
    Btw: What fork is that?
    It's a Specialized.

  7. #32
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    WOW!!!! That cup was difficult to break loose! Finally got the 36mm wrench in the mail today. Stupid ebay seller finally shipped 5 days after he was paid! I worked and worked on getting that cup off for about 10-15 minutes. After lots of liquid wrench and a little persuasion it finally broke free. (Remember drive side loosens by turning clock-wise.) Took a small brass brush and a rag and air gun to clean out the threads.

    Now onto BB sizing. Looking at 113mm or bringing in the chainring a bit by going 108. I buy VP alloy hollow spindle bottom brackets at a weight of right around 200 grams. Also you can find titanium crank arm bolts on ebay for about 10 bucks!
    Attached Thumbnails Attached Thumbnails Project Columbia-bb-finally-out.jpg  


  8. #33
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    Had just enough time after work tonight to install the titanium hollow spindle axle.

    About 150g. vs. 400++ that came out of it!
    Attached Thumbnails Attached Thumbnails Project Columbia-bb-hollow-ti-spindle.jpg  

    Project Columbia-bb-hollow-ti-hollow-spindle.jpg  

    Last edited by Rondo; 11-14-2012 at 08:56 PM.

  9. #34
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    Dang, that's a ton of weight saved!

  10. #35
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    Ok looking for opinions. I put together a Sinz crank & chainring, and BBG bashguard with blue bolts. Iím liking it!

    What Iím not sure about is the Odyssey BMX seat and carbon seatpost. Just not sure itís doing it for me. I have another seat setup on my titanium bike (gold post) which is a pivotal and is super light, (less than half the weight of the carbon post) and looks pretty good too but am worried about too much red, which is the color I would get.

    The stem and bars are carbon and I thought they would all tie in. My wife thinks the seat is ugly, maybe I should just find another butt-rest???
    Attached Thumbnails Attached Thumbnails Project Columbia-chainring-en.jpg  

    Project Columbia-chainring1-en.jpg  

    Project Columbia-seatpost-possibility1.jpg  


  11. #36
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    The question I would ask myself is, will the child like it? How important is comfort over weight savings in the saddle for a child?

  12. #37
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    That's a good idea. I'll have both on hand so he can see which one HE likes best!


  13. #38
    jr2
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    Hey Rondo... what happened? What's the latest?

  14. #39
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    I've had to back burner this project for a bit. Will get back to it when I'm not working 7 days per week.
    Last edited by Rondo; 05-15-2013 at 10:43 AM.

  15. #40
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    Ok back on the bike. Seems like Iím making this thing into something it wasnít meant to be and am having a little difficulty finding the right parts but am going to keep trying till I hit a total dead end.

    So hereís a question. Iím thinking about getting Shimano mtb XT disc hubs and lacing them up to 20Ē rims and going with hydraulic disc brakes. I believe the hubs have 9mm axles while the axles that are on the rims now are 3/8Ē. Can I use the XT hubs on this frame and do I need to mod the frame or hubs to do this? Or will the QR skewers work fine in the current frame wheel cut-outs?

    Also, Iím having a little difficulty finding carbon rigid forks for 24Ē wheel with the disc brake mounts. Anyone have a line on them?

  16. #41
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    QR skewers will probably hold the axel in the too-wide dropout OK but if not, you can just fill in the dropout slot with a bit of JB-weld epoxy and then file it to exact 9mm deminsion to get a good tight fit.
    IMHO- hydraulic disks are complete overkill for a 20" kid bike and add considerable weight over using decent V or cantilevers. The frame spacing might also be less than MTB 135mm axel width. I would look at using lightweight 130mm road hubs with rim brakes to save weight and fit in the frame better.

    THe tourney RD you got is pretty heavy. You could easily save 100+gr with a lighter RD. If only using a single chainring, no need for a long cage RD, a short cage road RC can work fine so long as the largest sproket is not too big for the RD.

    For inspiration on a much-lighter suspension fork, check out my daughters 20" project bike;
    Novara Pixie 20" project

  17. #42
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    If you are using disc brakes on a 24" wheel, you can use 26er forks, the geo may be a bit off. The bike my son had was a 24" Rocky Mountain Reaper, it has disc brakes front and rear, 24" wheels and the forks was a 26er. Come to think of it, his Specialized Gromhit freeride bike also has 26" Marzocchi AM forks. It gets more complicated with rim brakes. Also, I am using bolt on axles on both the Gromhit and his current ride (same fork I used on his Reaper 24). XT hubs can be converted to bolt-on by buying Wheels Manufacturing axles (Front 9mm by 155mm and rear 10mm X 178 (I believe, not 100%)).

  18. #43
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    Here is one company with a 20" carbon disk fork;
    CarbonCycles.CC :: Components :: Products :: Forks - Recumbent / Folder :: eXotic Carbon Rigid Fork for 20 Inch Wheel - Disc Only :: CC-F03-20

    (Same company also has a 24" fork if you want higher AC and to be able to re-use it on next bike when kid grows)

    Still fairly heavy at 750gr, comes with 200 lbs rider weight limit! You could probably cut down and modify a light-weight steel road fork to weigh less for a 20" MTB. Finding a carbon fork that is actually weight-optimized for a sub 100 lbd rider will probably be very difficult.

  19. #44
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    Quote Originally Posted by RSabarese View Post
    If you are using disc brakes on a 24" wheel, you can use 26er forks, the geo may be a bit off. The bike my son had was a 24" Rocky Mountain Reaper, it has disc brakes front and rear, 24" wheels and the forks was a 26er. Come to think of it, his Specialized Gromhit freeride bike also has 26" Marzocchi AM forks. It gets more complicated with rim brakes. Also, I am using bolt on axles on both the Gromhit and his current ride (same fork I used on his Reaper 24). XT hubs can be converted to bolt-on by buying Wheels Manufacturing axles (Front 9mm by 155mm and rear 10mm X 178 (I believe, not 100%)).
    Going from a 20" suspension fork to a 24" rigid form is probably not going to be a huge change in geometry. A 24" bike can be designed from ground-up to have the geometry correct when using a 26" length fork. Just putting a 26" fork onto bike designed for 20" wheel and fork would seriously mess-up the geometry, the head-tube & seat tube angles would be very slack and handlebars would be sky-high.

  20. #45
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    Thanks for the kind responses guys. Although I am concerned about weight it might actually be my second concern. First and foremost is to create a bike that will be safe for my son to ride and something he will be confident in controlling. The bike he has now he has problems stopping so I thought in building this bike the addition of good stopping disc brakes would be in order. ( just hope he remembers not to fully grab the left handle?) ;-)

    Weíve gone pretty fast downhill a couple times and it has freaked him out that the v-brakes donít work to well at high speeds. Me thinks he just canít pull very hard at 6 yrs of age. Heís a really good peddler so the heavier hubs should be ok. I know Iím taking a gamble that the disc clearance might be an issue but only one way to find that out. The bike had a shock up front so itís a little taller than a standard 20Ē fork. Would the 24Ē work?

    CarbonCycles.CC :: Components :: Products :: Forks - Recumbent / Folder :: eXotic Carbon Rigid Fork for 24 Inch Wheel - Disc Only :: CC-F03-24

  21. #46
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    Then there is this too which is a cheaper alternative but not really fond of the M-33 mounts showing on the front of the fork.

    Bloodline 24? Chrome Aluminum Fork Disc Brake Rigid BMX SE Haro Redline | eBay

  22. #47
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    Compair the Axel to Crown length of new fork options to the measured AC length of the bikes current suspension fork when compressed 20%. An additional 20mm of AC length changes the head tube angle by about 1 degree (slacker angle).

    I think the challange is that most any short fork you can find will be designed to take the abuse of a much larger rider performing huge verticle drops, probably 10X as strong as anything a kid can dish out to a fork so correspondingly heavy.

  23. #48
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    AC on current 4LB. (shock) fork was 35cm, and with sag was somewhere between 34 to 34.5cm

    The Carbon disc only fork is 33.9 so seems like it may be a perfect match.


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