how many miles do you have on the original setup?
chainrings generally, especially the 'new' ones (those made in the last 10-15 yrs) last an awful long time under serious hard ridin.
replacing a chain doesn' mean you have to replace the front rings.
more common is to wear the chain so much that one or 2 rear cogs (those ridden the most) may wear a bit too much.
I have a Truvatic elita triple which has at least 15K miles on it and the rings are way fine.
Not seeing your setup, I would still say the greater possibilities are
A. nosepicker really doesn't what he's talkin about
B. trying to sell you something you don;t need
C. covering some screwup
I'm always suspect of the 'something for nothing' deal, just because you're sucha good customer and we want to get you back on the road...
Shimano rings work fine on a truvativ crank ... and they are really nice rings.
triples work fine, if setup properly.
that said, a Shimano 105 or Ultegra triple is a nice crankset.
truvativ makes good stuff also.
if there is something 'wrong' with the truvativ cranks and rings, then they need to demonstrate the problem. This **** is not magical, smoke and mirrors stuff. Only their bull**** is smoke and mirrors.
Problems in the cable run (dirt, rust, kinks, etc.), worn and flimsy cables often cause problems which can be put onto the rest of the main drive train. A nice braided cable will set you back maybe $4 or $5 bucks.
cable housing issues (and hangups here cables enter and leave bosses and housing, like the BB area) can also contribute to shifting problems. Often its the combination of crappy cables, cable path and clogged housings which together make shifting an adventure.
Then, per the nosepicker, you give them $150+ bucks for a new crankset, and it doesn;t resolve the issues.
I always start with the simplest and least expensive area if the problem isn;t clear. $8 for 2 new cables is money well spent if you've never replaced them and the bike is a couple seasons old.
Then I make sure the housings are clean (not clogged with crud) and not kinked. Kinked gets replaced.
also not a big ticket item, but a real improvement over worn housings
everyone should have a chain checker. Park tools CC-3
, nashbar and performancebike
also have same tool for a bit less dough. All work real fine.
Even if a rider doesn't want to do the maintenance, you can still do the easy 15 seconds check of the chain condition and know exactly when to 'replace' the chain (I replace when checker shows .75% stretch). a no-brainer. And it assure much longer 'life' out of the cassette cogs and rings.
...next they'll be chargin you to replace the blinker fluid...