okay, mas madali na ngayon magbigay ng opinion...
first question: tama ba yung sukat ng bike sa'yo? kung dehins tama ang sukat, you're best option is to use your 7k budget to buy a new one!okay na yung trinx, 40% siguro ng nakikita ko na bike sa area natin (san pedro, binan, sta rosa, nuvali, canlubang, cabuyao, carmona) ay trinx. yes, ganun kadami! hehehe! at naia-akyat naman nila ng tagaytay via brgy. casile or via "cardiac arrest". tapos ibenta mo yang lumang bike para may budget ka for a good helmet.
kung tama naman sukat ng old bike and you really want to keep and upgrade it, i suggest you look for second hand parts to maximize your 7k budget. kung sakin yan, heto order of prioritization ko:
1. rim set or the whole wheel set - swerte at tyaga lang sa paghahanap. last Nov 2016, may nakuha akong wheel set for 3k (alexrims xd-lite + novatec hub + maxxis crossmark tire + stainless spokes and nipples. may kasama pang 8-speed cogs).
2. rear derailleur + shifter - abang ka ng 9 or 10. madaming nagbebenta nito. depende sa makukuha mo, baka kelangan mo din magpalit ng chain.
3. brake set - mechanical disc brake ay okay na at mas madaling makakita kasi madaming naga-upgrade to hydraulic.
then ipon mode ulit... next:
4. bottom bracket - kung sira na, palitan na ng sealed bearing type.
5. fork + headset + stem + handle bar - second hand: 800 to 1k may makukuha ka ng rigid fork like mosso, etc.; 800 meron ka na stem + handle bar; yung headset 500 meron ka ng brand new.
check ka sa fb: laguna bike tiangge - napakadaming nagbebenta ng second hand parts.
yung bike shop sa san pedro di ko matandaan exactly kung saan. basta sa loob ng bayan yun... yung malaking bike store. sa olivares-binan meron din bike shop, then may isa pa sa san antonio-binan, plus isa pa sa south city homes-binan. yan mga alam ko na maayos at nagbebenta ng affordable bike parts. jan ka din pwede tumambay para mag-abang ng mga naga-upgrade! ganyan ginawa ko nung nagbubuo pa lang ako.
here's the thread while i'm building my bike:
pinoymtbiker.proboards.com/thread/42730/back-on-saddle-xc-projectyung groupset at fork (both brand new) ang nagpamahal jan. the rest of the parts are mostly second hand.