Workshop tales, trials and disasters.
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4 posts • Page 1 of 1
This sound like something I should be able to Google up the answer to in less than a minute, but I haven't found anything.
I have a 4-bolt MTB triple crankset I want to convert to a single-ring setup. I've seen an article on replacing chainrings on a 5-bolt set up that said to bolt on the new the ring by going round and doing up every second bolt until they are all done (i.e. do up bolt 1, then 3, 5, 2 and 4). This obviously won't work on an even number of bolts, so is there another technique I should use? Is it like doing up a stem's faceplate bolts or should I simply go around in a circle?
Also, I removed the granny ring by simply going round in a circle and damaged two of the threads a little. Would this be because of my technique? The crankset is fresh out of the box so previous abuse is not a factor.
That's a general rule for anything you do up which has bolts/screws opposing each other around a component (on bikes, cars, fishing reels, vacuum cleaners..). The idea is that you gradually tighten opposing bolts in turn so the thing tightens without distorting.
To be honest, it's not that critical on a chainring, but it's a good habit to get into with anything.
In your case, tighten gradually 1,3,4,2 or similar. As they get pretty tight, just pinch up the bolts in rotation about a quarter turn each until they're fully tight.
As for the damaged threads, I can't imagine how you could damage them by undoing the bolts (unless you physically slipped and gouged them!). If they're new, it'd suggest they were faulty, or overtightened originally.
One last thing I thought I'd throw at the hive-mind is to ask whether there's any advantage between using loctite and marine grease on the bolts. I have both to hand so I might as well use the 'better' one, if there's such a thing. The ring is alloy but I'm not sure about the bolts (need to find them to check ).
As to gouging the threads, I can't see how I did anything wrong. It's a fairly low-end crankset though (Shimano Alivio), so the tolerances might not be the best and I guess most owners wouldn't get round to replacing the steel granny during its life anyway.
I didn't really think you'd gouged them! Depending on the damage, they could just be damaged from over tightening. Sometimes the threads can strip or even just fall away in 'part coils'.
You can't use loctite and marine grease, as the loctite is meant to be used on dry grease free surfaces. I'd suggest just a smear of grease in the threads unless you've had trouble with the rings coming loose before - then loctite alone is the answer. I just use grease, though.
I'd suggest the bolts/nuts are chromed steel - most are.
4 posts • Page 1 of 1
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