Viewing 14 posts - 1 through 14 (of 14 total)
  • Lefty onto a non-C'dale frame
  • z1ppy
    Full Member

    I have a lefty Max 140mm, and got it converted to an air damper.. wasn’t a cheap conversion, and made it work loads better. Now I found I prefer 29ers, so my faithful Prophet must go but I want to keep the lefty. No problem, you can get Project 321 or lefty-for-all conversion kits to make it fit tapered frame, and a spacer to convert the lefty to a 110mm 29er fork. Trouble is, it has a 510mm Axle to Crown, and a large gap between the clamps. So with my current 120mm 29er frame (520mm), it would steepen the head angle and raise the stem, neither of these are acceptable options (to me).

    So… I have to use spacers to fill the gap between the top headset and the top lefty clamp. Anyone thought about putting the spacer underneath the lower race, increasing the axle to crown & keeping the stem low? Pure genius or that way madness lies? 😯

    disco_stu
    Free Member

    Is that the PBR upgrade for the Lefty Max? I’m tempted to do the same for my Lefty, just wondering how expensive it is to do?

    z1ppy
    Full Member

    an arm and a leg.. I had one converted and another serviced at the same time, so can’t tell the exact price but somewhere in the £300 region IIRC. I had Tony@ Thumbprint tuning do the conversion , give him a ring to discuss it (his replies to emails are a ‘tad’ lacking)
    Improved the small bump sensitivity hugely, and made it a stupidly light 140mm fork (something like 1800g [mine’s a carbon jobbie] down to 1500g aprox), but was it worth it.. only if I can move it onto my next bike!

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    monkeyp
    Full Member

    Doesn’t sound unreasonable as the new Lefty’s have a spacer that can be placed above or below the head tube I think, however, the steerer setup has also changed so this may influence this

    amedias
    Free Member

    10mm, just so we’re clear here, you’re talking about 10mm, hardly a huge amount…

    find a headset with a bigger stack height
    use a headset with a bigger depth crown race
    fit a bigger front tyre 😉
    find a lower rise stem
    use a small spacer

    All of the above would work, or you could bung it on your new frame and see if the 10mm really matters? I’m assuming this is a theoretical on-paper-measurements geometry dilemma you’re having rather than a real world ride testing problem where you’ve discovered that those missing 10mm totally ruin the ride of your bike?

    DanW
    Free Member

    I was quoted £200 for a PBR upgrade by TF Tuning (great guys to deal with by the way)

    10mm, just so we’re clear here, you’re talking about 10mm, hardly a huge amount…

    find a headset with a bigger stack height
    use a headset with a bigger depth crown race
    fit a bigger front tyre
    find a lower rise stem
    use a small spacer

    All of the above would work, or you could bung it on your new frame and see if the 10mm really matters? I’m assuming this is a theoretical on-paper-measurements geometry dilemma you’re having rather than a real world ride testing problem where you’ve discovered that those missing 10mm totally ruin the ride of your bike?

    I agree 😀

    Bear in mind too that the thing that matters is the AC height taking sag in to consideration. Depends on the travel of your 520mm AC height fork but the difference most likely won’t actually be as much as 10mm taking sag in to consideration. A taller stack headset like a Chris King, perhaps even with a 3mm or 5mm thick baseplate would be my pick but I wouldn’t have thought this was necessary. I’m not sure if you could run a spacer underneath the lower cup with a tapered steerer adapter as the adapter might not have a wide enough 1.5 inch diameter section to accommodate both the Lefty clamp and the spacer. I don’t have one to hand to check

    z1ppy
    Full Member

    [Quote]All of the above would work, or you could bung it on your new frame and see if the 10mm really matters? I’m assuming this is a theoretical on-paper-measurements geometry dilemma you’re having rather than a real world ride testing problem where you’ve discovered that those missing 10mm totally ruin the ride of your bike?[/quote]
    I appreciate the replies, as even if i dont agree, there food for thought & pushing the idea further forward. All this is currently paper plans, but whether to buy a full bike or just the frame decision is based on it, so rather important to me, let alone the extra cost of buy a steerer conversion kit, i ain made of money. Will 10mm & a potential 1 degree steepening if the head angle matter.. Yes to me hugely, as the frame I want is already steeper than I really want to go currently. As for the options of changes, I don’t believe any would help, as the lower headset is already a large external one & how do you find out if one crown race is bigger than another? I’m already going to be running a 0 rise stem, & due to the design of lefty’s running a short as possible “-” rise stem would be awkward & potentially expense to test.. The sag point is interesting though

    I’m not sure if you could run a spacer underneath the lower cup with a tapered steerer adapter as the adapter might not have a wide enough 1.5 inch diameter section to accommodate both the Lefty clamp and the spacer.

    This is the crux of my issue, as I don’t know either, hense one reason for my post

    The-Swedish-Chef
    Free Member

    If you’re in to random emails, drop Jonas a line at http://cerrol.wordpress.com/ he’s a mechanic on a UCI team as well as an utter Cannondale fanboy/weight weenie, he’ll know/point you in the right direction.

    yourguitarhero
    Free Member

    Why don’t you buy a Cannondale bike with a lefty on it, sell the one it came with as new and put yours in it?
    Loads on Paul’s Cycles very cheap

    DanW
    Free Member

    Will 10mm & a potential 1 degree steepening if the head angle matter.. Yes to me hugely

    10mm difference will be less than half a degree steeper…

    how do you find out if one crown race is bigger than another?

    You can buy crown races of different thicknesses for various headsets such as Chris King. The same baseplates also fit some other brands. What this means is that the section normally attached to the top of the fork can be made thicker to push the bottom of the frame slightly higher. It is quite an elegant solution to getting the front end a touch higher.

    The sag point is interesting though

    What are the full details of the Lefty you plan to use and the 520mm AC height fork you are comparing it to? We can then work out the difference in sagged AC height.

    If you’re in to random emails, drop Jonas a line

    eliflap too 😀

    DanW
    Free Member

    edit: double post sorry

    amedias
    Free Member

    was about to post but DanW pretty much summed up what I was going to say.

    10mm = ~0.5degree

    And as we said, thicker crown races are available, also headset cup heights vary massively between manufacturers and models, look at the specs and you’ll be able to reclaim a few more mm there

    ie: +5mm crown race, +3mm bigger cup = 8mm

    we’re now talking ~3mm difference (fraction of a degree) which could be the difference between a new tyre and a worn one, let alone different tyre sizes.

    min length with 0 degree stem with lefty is normally ~80-90mm, depending on bars, but you can use -ve rise quite happily.

    But to the crux of the matter as you put it, I’d happily run a small shim under the headset/bottom of crown, but no more than a few mm (but as pointed out above that could possibly be enough)

    Have you tried calling Tony to chat about it? He’s a good guy and knows Leftys inside out, what they should be able to do and what they shouldn’t! Just ask him about his Lefty’d gravity bike made from welded together cannondale swingarms, or his bootless travel reduced Lefty CX fork!

    I really do think you’re tying yourself in knots over (theoretical) minutiae here.

    DanW
    Free Member

    Leonardi Racing and Project 321 are other good resources to ask about the shim underneath the lower headset cup since they are the ones making the adapters.

    As above, I don’t think I’d worry too much about running a spacer between the lower clamp and lower cup but aesthetically I’d rather fill that space with a taller headset cup and thicker baseplate first (if needed at all going back to the sagged height issue)

    z1ppy
    Full Member

    Why don’t you buy a Cannondale bike with a lefty on it, sell the one it came with as new and put yours in it?

    LOL, because C’dale don’t sell any bikes I’m interested in… cheapness isn’t my concern, the right geometry is.

    I’ve emailed Project 321 already and though I had a reply saying tech requests can take time to answer, it’s been a month.. I chased it this morning but ain’t holdin my breath.
    Minutiae it maybe but it’s minutiae that concerns me, so I’ll worry about it 😀
    I hadn’t thought to phone Tony, so maybe wil ring him and email to that Jonas.
    As for only being 1/2 a degree, that 1/2 a degree too much, and if I can add a degree ontop of that, it’d save me buying a slackset (future plans)..

    My Lefty, a carbon 140mm (in 26er) Max with PBR conversion, compared to the likes of Fox Float 32 29 120mm CTD

    (sorry rushed for time, will read the rest and reply later)

Viewing 14 posts - 1 through 14 (of 14 total)

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