Viewing 6 posts - 1 through 6 (of 6 total)
  • Stealth dropper to a kid’s 26″ frame (drilling and cable routing advice)
  • Premier Icon campfreddie
    Free Member

    Just about to start putting together Urchin’s brand new Voodoo Nzumbi 13″ 26-inch trail bike. It was bought new and then stripped completely before being sent off for new powdercoat (couldn’t stand the fluro orange) and then all new upgraded parts (RS Rebas, Zee gears, Deore discs, Fatbars, Thomson etc etc etc… just so he can try to outflash his daddy).

    The original plan was to hunt out a Thomson 27.2mm inline post, but I have been looking at some of these short-travel 27.2mm dropper posts (CX posts) which look pretty neat. I need to work out whether he will carry enough weight on him to actually drop the thing, but if he does, the next step is to work out how to fit one.

    The frame is not rigged for a dropper post and I don’t want to fit external routing, so the plan would be to fit a Shimano UN55 bottom bracket (he is using snazzy Hup 150mm cranks which take square-taper) which supposedly has enough clearance for internal cable routing. My concern at this point is whether the required gear outer will take the diameter curve of the BB cartridge (it’s a pretty small diameter) without causing too much additional friction om the cable… anyone have any experience here?

    If I can overcome that, I would plan to run the cable up through the downtube and then exit close to the headtube in a position as found on other framesets. I would drill a slot to take one of these https://www.chainreactioncycles.com/ragley-internal-cable-guide-3pk/rp-prod180333 which should bring the cable out at the right angle.

    I could use two more to these cable guides to come out of the seattube and then in to the top of the downtube, but drilling three slots into the frame does seem to be chancing my arm a bit.

    Any thoughts? I have seen all the ‘how to guides’ on drilling the slots. I am pretty comfortable that it is not going to cause undue failure to the frame (after all, all of those frames with internal cable routings are not beefed up in the areas of the exits anyway), and I’m not bothered about warranty as the only part left of the original bike is the raw frame itself (which has been through the powdercoaters).

    Premier Icon BearBack
    Free Member

    I internal routed a 2018 Scott voltage fr frame. Drilled out the triple crown fork bumper mount, dremmeled out some excess material at the BB shell to downtube junction as it’s pretty beefy down there and ran the cable.
    It’s really tight and the cable runs with a fairly significant bend to get from the downtube up over the 24mm spindle BB and into the seat tube. It then has to dodge the main pivot sleeve which is essentially a friction fit gap. Cable has to get push pure 5mm at a time. Wouldn’t be much fun to be constant raising the saddle height with a growing kid as I’d have to pull the BB to move the cable up. but the height in my case was fit and forget.
    Post operation was not compromised. I sold the bike to my neighbour at the end 2018. He’s done another 2.5yrs of riding on it and I just did an dropper inner cable replacement for him. First time its been touched and it’s been working just fine the whole time.

    Premier Icon BearBack
    Free Member

    Looking at the frame pics there could be plenty of space, but it depends on how the tubes all butt together and you’ll only know once you remove the BB.

    Premier Icon lardman
    Free Member

    Why? They’ll grow sooooo quickly, all your work and effort will be lost in a year or so. They don’t even care about this nonsense of internal routing etc:

    Spend the time riding with said ‘Urchin’ and not hiding cables. PLLEEEEASE.

    Premier Icon nixie
    Full Member

    There is a child specific dropper from brand x now. Supposed to be better suited to their lighter weight.

    Premier Icon campfreddie
    Free Member

    Great spot. Thank you.

    The fact that the bike will have only a couple of years for my son is an irrelevance. I change my bikes almost as often as I change my wives. I enjoy building up bikes so I will be equally happy to build his next bike when the time comes.

Viewing 6 posts - 1 through 6 (of 6 total)

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