Sweep wrote:Go for a ride mick

On a related point, while brucey is here, is there a recommended way to tighten the bolts?
Am I right in assuming that you work on opposing pairs (or pairsish with 5 bolt spiders) , tightening gradually , to keep everything balanced?
what you describe is like the usual method for tightening multiple bolts between two (fairly rigid) parts. If there are five bolts (say) then you would usually be advised to tighten them in stages, in a sequence such as 1,3,5,2,4. The reason for this is that if the bolts are tightened fully, in one go, in any sequence, from full slack, then
a) the part may distort when the first bolt is fully tightened
b) the part may move when the first bolt is fully tightened
c) the part may not be seated correctly as soon as the first bolt is fully tightened
It is not a bad idea to tighten chainring bolts using a similar method, because some of the same things can happen. However if the seating for the chainring is distorted (eg one bent or twisted spider arm) then the chainring will distort regardless; chainrings are almost invariably far less stiff than the spider they are connected to. Plenty of chainrings are made badly enough that if you install and tighten just one bolt, you probably won't even be able to fit some of the remaining bolts.
Thus (IMHO) the best method is to
a) fit all the bolts loosely, and then
b)
just nip them up (eg twirling the shaft of the allen key in your fingers).
c) double-check that the chainring is seated and also that the sleeve parts of the bolts are fully seated. Then
d) go round the bolt pattern and half tighten them all
e) repeat using full torque.
The main purpose of this is to use low enough torque in b) that even if there is some issue with the chainring or bolt seating, no damage is caused through premature bolt tightening. If fitting new (or different) chainrings, in a) it is a really good idea to check that the sleeve part of the bolt starts through the big ring, yet doesn't poke out beyond the depth of the counterbore; if it does then you need shorter bolts. If the sleeve is so short it doesn't start through the big ring, this is also unsatisfactory. Either situation can arise because chainrings vary in exact thickness and counterbore depth.
If you need to shorten bolts it is easy enough to shorten the sleeve parts, but there is a catch; the upper part of the sleeve is usually relieved, i.e. it may have no threads in it for ~1mm. This is often done because the male part of the bolt also has no threads on it near the head. Thus a matching pair of bolt halves will pull up until the head touches the top pf the sleeve, but a badly made or shortened sleeve may not permit this without the threads binding.
Because used bolts are often dirty, and/or the parts may not fit one another perfectly in various ways, I recommend that having cleaned and greased the bolt threads, it isn't a bad idea to run the male part into the sleeve fully and make sure that there is no binding and that the head will pull up far enough (preferably so that it contacts the top of the sleeve). If the bolt halves won't run into one another smoothly, then this can cause problems when tightening the bolts; you shouldn't need a spanner to hold the sleeve part of the bolt; if you do, it normally means there is something that is not quite right.
cheers