Frame tweaking: Pompino with discs and gears

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  • In preparation for another gruelling season of not-quite-coming-dead-last in cross races, I have decided to hurtle my idea of "modern bike technology" forwards several years to about 2011. Yes, it's time I learned about disc brakes – but unlike my racing style, i'm going to have to do this fast.

    Rather than buy an off the peg geared cross bike with disc brakes like some common pygmy, I have decided to modify my already unsuitable bicycle using hitherto untested framebuilding techniques.

    I plan to

    disc tabs and cable guides to the pomp.

    Not only that – in anticipation of future misguided attempts to fit geared equipment to this bike, I may as well add a derailleur hanger to the track ends while I'm at it, also using the suspiciously costly, weak and difficult TIG brazing method.

    Let's look at that we're working with:

    biek. this picture is about 18 months old but not that much has changed. the new fork is a brother something or other carbon disc thingie. It has some kind of disc brake mounts. i can't even remember what they're all called, what the difference is, and why i should care.

    i guess i should get a matching brake mount for the seatstay. then, the internet tells me I need to mount this rear disc tab at a very precise angle and location BUT BUT BUT guys how do I set this angle and location when dealing with an adjustable rear wheel setup such as what you might find with horizonatla track ends – HMMMM!?!??!?!111111 that's a problem. as i say, i've never knowingly touched a disc brake, so this is all new to me.

    bazzing the derailleur tab on is less of an issue. it should look something like this:

    i will need one of you to send me an old dropout that i can grind down. not joking, please sort me out.

    FAQ
    Do you have a TIG welder yet?
    jesus get off my back man

    what wheels?
    i'll have to rebuild my current ambrosio nemesis (?) rims to some appropriate disc hibs. please can someone just link me to something or sell me something? front should be easy enough but rear i dunno if you can get 120mm disc hubs.

    what bar tape?
    the stuff you use for squash raquets

    will you respray the bike?
    yes, in that i will cover the newly amended parts in spray paint of some description. the current overall powder/paint job is not the best, so i really don't care about looks.

  • 120mm disc hubs.

    Keep dreaming!

  • looks like a good plan!
    I had this exact idea with my sweet fixie but instead i'm gonna cold set it to 130, use a dmr sliding dropout

    for the gears and boring old rim brakes until i find someone that i can trust to weld cheaply.

  • stop dreaming! tidy.

  • I did wonder for something I was looking at if you fitted a Hope Pro2 Singlespeed freehub to a normal Pro2 hub with a cut down axle it would give you a 122mm OLN hub with a freehub that can take 7 sprockets.

  • You can also get 116mm trials hubs which would work I guess

  • cool, i think i have an old dropout in the box, happy to send, i think i fucked it up at some point then used it as tig practice.

  • Cheers dood. i will pm you.

    For reals also, how do you site a rear disc tab for a sliding dropout?

  • If it's IS tabs then you can get ones with long oval holes that allow some movement.

  • That's how Surly do it. I think it's the same on the Pompetamine. It's a bit of a pain getting chain tension and disc alignment at the same time, but the simplest solution.

  • ah, the Pompetamine's tucked inside the rear triangle. Probably preferable if you have room.

  • thanks @Jon.

    I found this image on ceeway but can't quite work out how to order it.

  • Email them, they send you a quote and a link to pay

  • cheers bud. i will put together a shopping list

  • christ preserve me – can someone answer this simple question: do rear cable disc brakes have cable outer along the full run of cable between brake lever and calliper?

  • If you want it to. My genesis does have full length outer but no reason you couldn't put a cable stop at either end

  • However if you want to go hydro later you may wish you just had cable guides rather than stops

  • i've just found out disc hubs are dished

    makes sense

  • Good to see FAQ s in a build thread

  • @svenhöek is your go to guy for fitting disc brakes to track bikes

  • I did wonder for something I was looking at if you fitted a Hope Pro2 Singlespeed freehub to a normal Pro2 hub with a cut down axle it would give you a 122mm OLN hub with a freehub that can take 7 sprockets.

    i like the sound of this. @svenhöek do you have any knowledge of using a 116mm trials hub (such as this) in a 120mm frame. any insurmountable chainline issues?

  • All the narrow hubs seem to be threaded which limits cassette options. This gives you a freehub option if it works. Not taken it beyond concept, so things to consider;

    • for Pro2, think it might be same for pro2 evo or pro4 as long as both hubs are from the same family (pro2 evo; thicker axle than pro2, pro4; same axle but wider ratchet shell than pro2 evo)
    • the pro 2 ds flange offset is 12.5 mm narrower than the SS pro2 hub, so with narrower SS freehub will move oln 12.5mm inboard... I think (critical to make this work - need to check).
    • is the pro2 SS freehub compatible with the pro2 135 hub shell in terms of ratchet diameter?
    • will the wheel dishing work with the centre line on the pro2 hub moved to the drive side with the ss freehub fitted - can work this one out?

    I would phone Hopetech to talk it through with their service team / hub specialist (they are rubbish at answering emails but really helpful over the phone). They might have another solution.

  • I've respaced a few of these frames to 130mm with no problems, which opens up your options significantly.

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Frame tweaking: Pompino with discs and gears

Posted by Avatar for fizzy.bleach @fizzy.bleach

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