Mudguard eyelets woe

Discussion in 'Bicycle Mechanics and Repairs' started by jdapayne, 24 Aug 2007.

  1. jdapayne

    jdapayne New Member

    I got myself a new Giant SCR 2 about a week ago (it's my first road bike, but that's a different matter). Seeing as I live in Manchester most of the time, and it's only dry there for about 4 days a year, I wanted to fit some mudguards to it (part of the reason I chose the scr is 'cos it would take mudguards).

    Anyhow, I just got a set of SKS chromoplastics from wiggle today, and I've been trying to fit them. The bolts that came with them didn't seem to fit the eyelets on the fork properly or something, and being both stubborn and stupid, I forced them with the effect of stripping the thread, and actually getting half a bolt snapped off and stuck in. So, after that essay - three questions really:

    1. I thought that the thread would be standard, and the bolts should fit properly. Am I wrong, or are the eyelets on my bike just rubbish?

    2. How do I get the half bolt out?

    3. Once I've done that, how do I manage to actually attach these things (short of buying a set of clip on mudguards)?

    Cheers in advance.
  2. starseven

    starseven Guest

    You must have really worked at it to get a steel bolt to snap in a alu/carbon fork!!!

    Now you are there i would carefully choose a new or very sharp drill just under the diameter of the bolt and drill it out. it may not save the thread but you can always use a nut and bolt to hold the mudguard.

    Good luck , however you do it.
  3. Elmer Fudd

    Elmer Fudd Miserable Old Bar Steward

    My best suggestions are :-
    Can you get some molegrips on the broken bolt anywhere ? If so, screw it in (or out, depending on what side you can get hold of).
    You'll then need a tap set and wrench the next size up so measure one of your good bolts, e.g. a 5mm (machine made) bolt will actually measure about 4.75mm. Use the No. 1 tap (the one with the longest taper at the front) and force it to start, once it starts let it pull its own way through, with alloy this will be a piece of pish, with steel may be a bit harder but only going up 1mm (.040") should be no problem at all, just take your time.
    You will of course need a new bolt of the same size as the thread diameter you have just tapped.
    Hope that helps a bit.
    And, remember always start a screw / bolt off with your fingers, you can then feel whether it has 'bit' or cross-threaded.
    BUT! if as Starseven said they are carbon, you might wish to ignore the above as I have no experience of these.
    N.B. this is all easy when you have spent your working life in engineering and you basicallly have all these types of tools in your shed !!
  4. Tim Bennet.

    Tim Bennet. Entirely Average Member

    S of Kendal
    Without being rude, and with only the above information on which to guage your mechanical prowess, I would really recommend getting someone else to do it. Extracting the broken stud shouldn't be difficult with the right kit, but it is possible to make things much worse.

    I have never seen any eyelets that weren't standard size. However, on new forks and frames, the threads are often full or paint or lacquer. They frequently need 'chasing out' with the right size tap. Again your local bike shop will do it if they have a real mechanic and not a half trained monkey.

    I don't know what side of Manchester you live, but if you can't find anyone you trust to do it, you do have Hewitt Cycles up at Leyland. Paul is a time served engineer who can be trusted to do any sort of bike work, but don't expect him to do it as a 'walk in' job on a Saturday morning!
  5. OP

    jdapayne New Member

    Thanks for the advice guys. I don't have any tapping equipment or anything like that, so think I'll be making a trip to the lbs to see what they can do.

    The funny thing is, I'm sure I didn't force it *that* hard, so I'm surprised it did snap. Well, it's nice weather at the moment anyway, so it's not too urgent, and I might wait till I'm back in Manchester (where I'm not at the moment) and take it to Hewitt cycles.
  6. Maz

    Maz Legendary Member

    I say get it to a bike shop and let them have a crack at it. I had the very same problem trying to fit SKS guards to my Dawes Discovery...bolt head sheared leaving the shaft in situ. None of the supplied bolts was the correct diameter for threaded hole in the fork! In retrospect what I shouldve done was get a narrower bolt, pass it all the way through the hole and nut-fix it on the other side.
  7. TimO

    TimO Veteran

    Sounds like the threads needed cleaning out. Probably a bit late now ;), but you needed a tap like this Park Park TAP-8

    (and probably a Tap Wrench something like this).

    I fitted some mudguards to a friends Halfords bike a few months back, and managed to get away without chasing the threads out, but I was very careful and just about got away with it. A tap or similar would have helped a lot. I vaguely remember seeing mention of a similar tool that was designed to clean out threads, rather than cut them, and was safer for this sort of function rather than using a tap, anyone know what it was, or where to get one?
  8. OP

    jdapayne New Member

    I managed to clean out the other three holes (after realising that the paint in there helped me get the bolt stuck) just by using bolts and being very careful. Screwed them in a bit at a time, removing them to blow away the debris each time, then going in a few mil more the next time.

    I took the bike to the lbs and they told me they didn't want to do it (as they might to more damage), but recommended drilling from the wheel side. The result is, I've managed to get some sort of hole going through, so I'll probably bodge something with a smaller diameter bolt and a nut on the other side now.
  9. Steve I

    Steve I New Member

    Hi, I've just registered on here to be able to post on this. I too bought a Giant SCR 1.5 (same frame on all the SCR range) about 2 weeks ago. I always check the threaded eyelets on any new bike I buy. The bottle cage and rack eyelets were the standard 5mm and were fine. I tried one of the 5mm bottle cage bolts in one of the mudguard eyelets and oddly it wouldn't fit. I then tried all the rest of them, and even tried screwing the bolt in from the backs of the threads. No joy.

    I did some engineering training when I was younger, and do know a bit about thread technology, and I am aware that paint can stop a bolt from screwing into a thread. However, there is no paint on the fork eyelets, and in any case the rack eyelets were coated in paint and a 5mm bolt screwed easily into them.

    As luck would have it I found an odd bolt that screws in perfectly into the eyelets. No idea what it is, but it's 4.5mm in diameter, and comparing it to a 5mm bolt it has a different TPI, so that shoots the paint theory down, paint cannot alter the number of threads per inch. I've got no idea why Giant didn't use a standard 5mm thread in the guard eyelets, but I can state for certain that it most definitely is not a 5mm thread. Giant haven't replied to my emails. I expect to see quite a few more posts like this as people try to fit guards to these frames.
  10. I to have the same problem with the front eyes the rear seem to take a 5 mm bolt are these your findings, I think i will take my bike to work and get the fitters to tap the hole to fit the 5 mm bolts.
  11. I rang Giant yesterday about this problem they claim they weren't aware there was a problem, they promised to sort it and let me know the outcome, I contacted them again today and they assured me that the threads are the same as the bottle bosses as they had tried the threads on a new bike and it was paint, anyway they told me to put some oil on the threads and with an allen key ease the bolt through and sure enough it works, you must do this very carefully and not just screw the bolt straight in just screw a couple of turns and undo and so on it worked on my bike.
  12. Mortiroloboy

    Mortiroloboy New Member

    I have a SCR4, I have noticed that the eyelet threads on the rear drop outs are easy to start off, by finger, but do get progressiviely harder the more allen bolt disappears into the thread. there was a lot of paint around the threads BTW. Same on the rack eyelets at the top of the seat stays.
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