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Things you can do yourself and things you can't do

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  1. AKen
    Member

    After many years of use, it's becoming increasingly apparent that my front chainring needs replacing - the wear is past the 'sharks-teeth' stage and the chain has started to slip when under pressure. So, I'd value any advice on the question - Is changing the chainring something that I should try for myself or would I be better getting a bike shop to do it?

    My bike repair and maintenance skills are at the tyre-changing/gear adjusting/brake-block-replacing/chain-replacing level and, whilst I would like to be able to do it, if it's going to take many hours and leave me red-faced and sweary then I would rather just avoid the grief (and avoid the possibility of taking things apart, not being able to put them back together again and having to turn up at the bike shop with a box of bits for them to re-assemble.)

    It's a single ring at the front and I imagine this would make it a simpler task but I would like to know from someone who's done this how hard it actually is and how skin I will lose from my knuckles whilst doing it.

    Posted 12 years ago #

  2. chdot
    Admin

    Not clear if it's a removable ring - in which case fairly easy - Allen key should be enough.

    If very tight/rusted could damage your knuckles...

    Posted 12 years ago #

  3. Cyclingmollie
    Member

    The only problem is that there's a slot at the back of the chain-ring bolt which takes a special tool to prevent that half of the bolt turning while you loosen/tighten the outer hex-key part. If your bike, like mine, is grimy though the rear part may stay in place through grime-stiction* in which case it's an easy job, I think.

    *copyleft

    Posted 12 years ago #

  4. lionfish
    Member

    This might be an obvious answer, but a good compromise is to go to the bike station on Wednesday evenings or Saturdays (I think - check!). There they'll have all the tools you'll need, gloves to stop you getting covered in stuff, tea, and help/advice on how to do it. Plus instruction manuals, cheap parts on-hand, etc. All for ~£3-4/hour.

    I didn't mean that to sound like such a sales-pitch! But it's where I do all my beyond-basics repairs.

    btw: Also you'll probably need a new chain by now too. Are the other cogs ok? (I don't know technical terms yet :)... if not you might want to replace it all at once (otherwise, one thing wears out the other things, or that's how it seems?...someone with more knowledge might need to correct me :)

    Posted 12 years ago #

  5. Uberuce
    Member

    It's an easy one. Evidence: I did it without fuss. I used a flat screwdriver to bodge past the groove that Tom mentioned, but the actual tool would only have saved minor fruity language.

    There's the usual variety of arm/length size and since the biggest market for single chainring is fixed-gear/SS you'll have to check for 3/32" versus 1/8", but once you've got the right one, the actual swap is just a matter of undoing the bolts with an Allan key, swapping the rings over and tightening them back up.

    You'll almost certainly tighten them up slightly off-centre at first, but it's simple enough to pop the chain back on and see where the wobbles are, then readjust so it runs smooth.

    Posted 12 years ago #

  6. AKen
    Member

    The chainring has four allen-key shaped sockets that appear to attach it so I'm assuming that it's removeable!

    Thanks for all the (almost instant!) advice.

    Posted 12 years ago #

  7. chdot
    Admin

    Measure between the holes -

    http://sheldonbrown.com/cribsheet-bcd.html

    to get the magic BCD number.

    Posted 12 years ago #

  8. kaputnik
    Moderator

    A flatheaded screwdriver can work, however the "special tool" is both bent at a right angle (so you hold it from above, below, rather than through the frame) and has a little notch in the head that pops into the hollow part of the bolt to prevent the tool jumping off. That's the theory anyway. The EBC starter tool kit contains one.

    Worth soaking the bolts with WD40 or similar before attempting this if it's been sealed a long time.

    Find correct allen key, pop it in the bolt and then get the rubber or wooden mallet out and give it a whack. Keeps your knuckles out of harms way and should give enough of a shock to the bolts to loosen it and allow you to finish the job by hand.

    They can get VERY stiff and sometimes even hitting the allen key doesn't work, and requires a large wrench with which to drip the allen key to get sufficient torque. They tend to fly apart with a crack when they do loosen, so make sure you position your hands on your tools in a way that they aren't going to jump forward when the bolt suddenly unseizes and crank off the frame or crank and do you a mischief.

    Posted 12 years ago #

  9. crowriver
    Member

    If you have the right tools, do it yourself. If it's a crank with fixed chainrings that are not removable by themselves, the job is more involved and costlier as you often need to replace the entire crankset.

    If you don't have the tools, or you find it tricky, just take it to the shop. Won't cost much in labour. Some shops are okay about adding parts that you supply, others prefer to order themselves: check beforehand.

    Posted 12 years ago #

  10. Arellcat
    Moderator

    Measure between the holes

    Some of us, pre-Sheldon magic, used good old trigonometry and a pair of vernier calipers. The more familiar you are with the variants, the more easily you can tell just by looking. Old school? 110mm. Hyperdrive? 94mm. Campag? 135. Shimano? 130, and so on.

    I suppose you know you're happy doing your own maintenance when you own three crank extractors.

    Posted 12 years ago #

  11. AKen
    Member

    Thanks to all who gave me advice last week. I took lionfish's suggestion, got a new chainring and went along to the bike station to have a bash myself. After reading kaputnicks post I was anticipating a battle but in the end it wasn't too bad - three of the four bolts came out without fuss and only the fourth required use of the tool to hold the back of the chainring bolt.

    New ring was fitted successfully. It was amazing how much better working with a stand was - rather than crouching over the bikes and very handy to have someone there to ask stupid questions of - like which side of the chainring should face outwards.

    Posted 12 years ago #

  12. Smudge
    Member

    "I suppose you know you're happy doing your own maintenance when you own three crank extractors. and none of them fit the bike you're working on"
    Fixed that for you ;-))

    Posted 12 years ago #

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