Since I am more familiar with MTBs, most of my points would be relevant to these only...
Anyone seeking to build a bike should concern themselves with 4 components first and formost - in order of importance - Frame, Fork, Wheelset and Crankset.
Frame:
Generally, the frame really makes or breaks the riding experience, check for the geometry and sizing before making a purchase - frames these days come in a variety of shapes and materials and the choices can be bewildering. Start with the decision of what kind of riding you intend to do, remember, while the trend these days is for superlight bikes with plenty of travel (5-6" or more) you may find yourself with too much bike to handle when running longer travel rigs. In SG, you're not going to find any double black diamond trails, so there's no real point to getting anything beyond 6". Therefore, if buying a full-suspension frame, be wary of the amount of travel that you really need. Also, be aware of the geometry, best bet is to go for test rides. While carbon is the most "in" material these days, it's not necessarily cost effective or the best option, esp when buying from one of those smaller or unknown brands - not all carbon is of the same quality and a frame failure can lead to catastrophic results.
Fork:
When chosing your fork, consider what features you need as well as the geometry of the overall bike - it's not really necessary to match the travel in front with the travel in the rear - although many advise it. The more impt aspect to consider is the ride geometry - if the fork is too short/long, it might affect riding adversely. There are also many features avail in the market - consider what you need rather than going along with what is "popular" or what is being pushed by the shopkeeper. Consider features such as a remote lock-out and adjustable travel, if you figure you need it, don't go along with the shopkeeper when he proposes a product that does not have it - it's what YOU need, not what the shopkeeper thinks you ought to get.
Wheelset:
The rotating surfaces affect the feel of the bike immensely, particularly the sensation of weight. When upgrading an existing bike - the wheelset usually makes a dramatic difference, so get the lightest, most durable set you can afford. Also note: when purchasing a bike, a lot of shops substitute components such as the hubs, rims and spokes for lower end stuff to keep the costs down - so a mid-range bike might come with low-end wheel components. Try to plug for a good wheelset, it makes a big diff. not just in terms of performance, but lifespan - budget wheels may not be able to take the strain of more demanding riding. To drop the weight on the wheels, lighter tubes are a good option, but for those who are really into weight reduction, going tubeless is an excellent avenue, you also get to run lower pressures for increased grip and get greater pinch-flat resistance as well.
--Tyres> Tyres have a huge impact on the ride of the rig, grippier knobby tyres are generally great on the trail, but will increase rolling resistance on the road, while those which offer less grip may be faster but unsuitable for the trail you intend to ride - it's all about compromise. Also, note the kind of tread pattern - some tyres clear mud well while others get really fouled in the mud.
Crankset:
The crank is probably the most important component of the drivetrain particularly when it comes to rider "feeling". Budget cranks not only tend to be heavy, but they might not be as efficient in terms of power transmission. A good crank must not only be light, but very stiff - cranks with wobbly arms are a serious drag on performance - you'd be suprised at the difference a good crank makes to power transmission.
<<neO.n>>
- P.S. For any of those who are thinking of getting into biking fairly seriously, I'd recommend the following rigs (I've test ridden them both and found them to be excellent choices):
GT Avalanch 1.0 : (Hard Tail) Excellent ride, with great spec for the money. ride geometry is comfortable, but also very capable - you feel capable of taking on lines with more confidence that what you would normall associate with a hardtail at this price point. The rock shox J3 that comes with the bike as standard is also suprisingly good for a budget unit. Price is around $900 and the frame is a unit that you'll find quite worthwhile to keep and upgrade even as the components start to wear out. I took my friend's GT 1.0 out for a spin and almost didn't want to give it back - it doesn't feel like a budget bike at all.
Specialized FSR XC : (Full Sus) This is a relatively cheap intro to full suspension. The FSR XC features a tried and proven design, and the bike is plush but quite responsive and holds difficult lines with relative ease. While it comes with V-Brakes instead of disc brakes, don't be put off, disc brakes may be fashionable, but for the money, they would probably have had to spec some dopey, heavy, low-budget discbrakes, as it is you get quality SRAM Vs and the option of upgrading to disc brakes at a later date if you really need it (the bike is disc brake ready). Price is around the $2K mark.
For those who want the thrill of custom speccing, and if you're more familiar with the parts and the kind of performance you're looking for, you can always custom spec - this was the road that I took after getting my feet wet. As always, feel free to discuss
Cheers and happy riding
<<neO.n>>