Mechanics and Fixing Any Questions Answered

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  • What should the increments be when I micro adjust my 8050 front mech?

    It’s not touching the chain but 0.15mm clearance according to my feeler gauge. When I move it outboard one notch, it’s very nearly 0.5mm and doesn’t seem to do the overshift then come back in.

    Is micro adjustment supposed to be done in big/big? That’s what Shimano seem to say say but it sounds counterintuitive to me.

    There was no rubbing when I unleashed my massive 400w sprint on a little test ride but I don’t like things not being quite right.

  • If it's symmetrical then go ahead and buy a symmetrical BB. If not then go down an internet rabbit hole looking for the assymmetrical one.

    I dunno if the 110mm un300 that @jtfh linked is symmetrical but see further up the page for my discussion of the 110mm un55 not being symmetrical.

  • I think the increments are 1mm and the recommended gap is 0.5mm but it's all in the Shimano manuals.
    Don't always need to do everything by the book, some chainrings are wonky or you can have massive power.

  • but a least you can still use it with a 1.5mm spacer :)

    (it is the non-driveside that is longer)

  • It it's coming off anyway, you can take it out and see what it says on the label.

  • The latter certainly won’t be a problem.

    So the micro adjust isn’t very micro? Sounds like it’ll be more exact to use the limit screws to get it bang on.

  • Seems like I was making shit up and the micro adjust is 0.2mm with Shimano and 0.25mm with AXS. That's for the RD, can't find any data on the FD.
    Been thinking about it and never got to a point I can't center it enough not to rub inside or out, can't be as bad as 1mm steps.

  • I have a lynskey 29er. It’s a bit old now but otherwise fine. However it only takes a 27.2 seat post. The seat tube has an insert and it appears it reduces the size down from 31.8 to 27.2. I’d like to remove the insert and get the frame drilled to take a dropper post.

    There was a member here who had a lynskey made on one ti bike and he had a similar insert removed.

    Who would over such a service and what’d be the likely cost? Or should I try to use caustic soda to remove the insert and just get a bike shop to ream the seat tube of what ever has been used to bond the insert to the frame?

  • The thread of my 1inch fork is too short for my frame.
    Where in SW London can I find a bike shop which could extend the thread of the fork?
    Do all the bike shop have the tool to do it?
    How much would it likely cost?
    Thank you

  • I'd say a fair few will be missing it, aim for the ones that might've built the odd frame in the past, then be prepared to wait a long time to get it done unless you're very charming and offer many beers.

  • London Cycle Workshop in Sheen or battersea. Very quick turn around. Offers of beer like @snottyotter said will make it go even faster.

  • Thanks for both of you. I ll try the closest bike shop from my place (cycleopedia KT6) early tuesday morning and I ll go from there. I only need 1/2 inch of thread but I do understand I certainly won't be on the priority list.

  • I have a rear tyre clearance issue that if anyone could advise on would be greatly appreciated.

    I bought a boschetti (probably custom 90's tri) frame recently and the tyre clearance to the seat tube is tiny. A 700x23c clincher around 100psi on 15/18mm diameter rims rubs on the seat tube. Due to the move away from skinny tyres, 18c or 20c clinchers are hard to find and most are race orientated so don't have much durability. The clearance to the seat tube is around 22mm at on a 700c wheel without tyre. I have only really used clinchers but wonder if tubeless may have a lower profile tyre as they are run at lower pressures, especially on a wider rim.

    The skinny tyre then leads to wheel width questions. The ETRTO recommendations seem to be on the high side. What would people recommend for wheel internal/external diameter for thin tyres as a real world low level limit?

  • AFAIK michelin dynamic classic come in 700x20c, and have a bit of puncture protection. Conti supersonics are sometimes cheap to buy second hand - I recently got a pair from kleinanzeigen for 30€, but they have no protection.
    can`t say anything about tubeless, no experience in this area.
    for the width: I´m not sure if I understand you correctly, you mean the distance from rim hook to hook? "traditional-sized" narrow road rims should be okay, I think the most of them are like 13mm-ish internal.

  • Hello. Is there any danger of riding with a seatpost above minimum insert? The previous owner cut the post and now I ride with the seatpost maybe about 4cm in the frame. I don't have a tape measure but about 4cm ish of the post is in the frame.
    I can't see the old min insert but I assume it's more than 4cm. Bike is a Dolan Pre Cursa, with the alu alpina seatpost.


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  • You want to Seatpost to be inserted past the sections where the tubes meet otherwise you’ll end up with a crack in the frame. Someone will come along soon to explain in more detail

  • Ok cool. I'm not convinced it reaches the top tube to be honest. Just gonna replace it. I didn't even think of it doing damage to the frame.
    Cheers mate

  • Is there any danger of riding with a seatpost above minimum insert?

    Yes. You're increasing the leverage exerted by the seatpost, by effectively moving the pivot point at the seat clamp, and there's a risk the increased load at the end of the seatpost will deform the seat tube.

  • New seatpost ordered! Cheers

  • Does anyone know what bolt I need to secure flat mount sram force calipers on to the frame (calipers are on mount already)

    ...and where I can buy them?


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  • Took a spill today and the my stem came round into the top tube - worried this might be a crack but hoping there’s a chance it’s just the top coat. Tap test hasn’t revealed anything that obvious but I can’t stop thinking about this


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  • Carbon frame? I'd remove the loose paint with a razor blade and see if the carbon underneath is damaged. If not, quick splash of touch-up paint and you're good to go.

  • Yeah, first carbon mtb. That’s a good shout, will do that and see what lies beneath!

  • Given that it's a surface impact rather than a proper crash - i.e. head first into a tree - it should be possible to see if the strands of carbon have been displaced or if it's just surface damage. Even if the carbon is damaged, it's an easy fix.

  • Cheers, appreciate the reassurance

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Mechanics and Fixing Any Questions Answered

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