New, cheap mountain bike: What's most likely to break?

Question

I have a very cheap (less than USD $100), new mountain bike I'm about to break in on a 2-4 hour ride on a mountain trail. I'd like to be prepared for equipment failures or problems - can anyone suggest what's most likely to break (or have problems) first?

I already have a spare inner tube (and pump!) to handle a punctures, and expect to have a sore rear end, anything else?

(thanks for the articles warning about cheap bikes - I should probably add that I will use this bike only once a year at most, and can't afford a better one anyway - if not for cheap bikes I'd just be walking. For anyone coming across this question considering buying a very cheap bike, see the link posted in the comments and make sure you know what you're getting into!)

Update:
Thanks for the answers so far. Thought I'd do a quick post-mortem for anyone interested. I went on the ride (Oaks fire trail, very scenic, good fun - Blue Mountains, NSW, Australia).

I managed to escape without notable failures on the bike, though I think the cheap suspension fork had already seized up and the derailleur only changed gears when in the right mood.

In our group of 15, we had 3 flat tyres and a broken chain (all on $1000+ bikes, oddly enough - maybe they were just riding them harder).

The most unexpected problem was with replacing punctured tubes on the expensive bikes. The tube valve hole in the fancy rims wouldn't fit the spare tube's larger (standard car size) valve, and many pumps couldn't fit the fancy tubes (to re-inflate them once patched).

Answer 1

Information about the specific components would help. I am not sure what will break first, but the derailleurs will probably be the first component to need servicing - especially if you purchased this bike from a sporting goods retailer instead of a bike shop. Brakes will probably be needing some love in the near future. If you ride on trails at all the fork will probably end up needing some maintenance quickly. The wheels will also probably go out of true pretty quickly as well.

One thing you can do to help keep the bike in good running order is to frequently put chain lube on your chain to keep it, your derailleurs, and cassette well lubricated.

Answer 2

Cheap “mountain” bikes are not up to mountain tracks! If you would not consider walking along the track in a pair of sandals, then the bike will likely break very soon if you use it on the track.

However cheap “mountain” bikes are good on roads that have some pot holes and are easier for most people to ride then a road bike (but a lot slower). They also allow you go along tracks that have some mud or a few rough spots.

If you are nice to your bike, and don’t expect it to cope with any hard of road usage, I would not expect anything to break quickly. However you will have to adjust your derailleur and brakes, trim your wheels and tighten up loose bolts and nuts a lot more often than on a quality bike.

You may well find the first think to break is your will to put up with a cheap bike!

Answer 3

When I was fixing bikes for Christmas Anonymous we got a fair number of Wally World grade "mountain bikes".

The most common failure was probably the shifters. Twist grip shifters were bad on about half the bikes that had them.

Otherwise, damaged wheels were probably the biggie. (Though it may be that some of these were garage accidents vs from riding.)

Of course, bearings always needed tuning up and wheels needed truing, but that's not uncommon for any bike that hasn't been maintained since it was unboxed.

The bikes actually appear to withstand considerable abuse. The only structural problems we saw were really old, rusty bikes, or bikes that had apparently been damaged in the garage. I'm guessing that tire, drive train, and shifter problems are far more common than any sort of structural failure.

Answer 4

Becareful, I've heard from fellow riders of kids tackling Welsh tracks (notably the Marin Trail in North Wales), and the suspension fork riping itself loose from the front of the frame. The split happened where the cross bar and down bar (right name?) meet the headset. Apparently the kid had got the bike for christmas and rode a couple of trails, and literally the welds weren't strong enough the frame pulled itself apart. Now that's a scare story, not to mention a parents nightmare! I heard the kid was very lucky, and escaped with cuts and bruises.

Personally I've taken a Raleigh Activator (about £200 new, 15 years ago) along the same trail and managed to bend the front forks quite considerably. Mind you that was a steel frame, and the aforementioned story probably was done on a aluminium frame. Of course, it all depends on the welding, as I've crashed a old steel road bike and the welding came apart on the rear chain stays.

So just becareful have fun, and if you see any hairline cracks appearing on the frame. Get off, and push it home.