Chain or cassette problem
 

I've started having a problem with my mountain bike where I thought the chain was skipping or slipping and then another problem came up that I didn't think was mechanically possible. I would be coasting along and then start pedaling and it would crank freely while I was pedaling forward, as if I had been pedaling backwards. I'd stop pedaling and look down, thinking my chain had come off again, only to discover that it hadn't. Then I try pedaling again and everything is back to normal. This has happened a couple times now.

So when my chain supposedly skips or slips, causing a jolt when I pedal, I don't know if that's actually what's happening, or if it's a problem in the cassette where it fails to "catch" and drive the bike along. When it jerks like that, sometimes it causes the chain to come off the front chain ring. When I thought it was a gear problem (since I always ride on the second gear up front), I tried shifting it to the smallest chainring to see if the "skipping" would happen there too. It did! So that makes me think that it has nothing to do with the middle chainring gear being worn out. It also skips no matter which rear gear I'm in.

Any ideas? I don't have all that many miles on the bike. Probably well under 1,000.

If the bike is freewheeling when you are pedaling it points to a freehub issue and the skipping is probably happening because the hub is disengaging under load.

You would not wear out a chain ring in 1000 miles and fact it happens over multiple chain rings should eliminate that as an issue.

If the bike is new it should be a warranty issue... a defective freehub body can be replaced.

Odds are that inside the freehub section of the hub, the ratchet area is packed with dried grease or has some rust. Either could be enough to keep the light springs from engage the ratchet solidly when you switch from coasting to pedaling.

Often if the situation isn't too far gone, the unit can be saved with a solvent flush and relubrication. If it's badly rusted (inside) it calls for a replacement of the freehub module. If you prefer to do your own service, search "servicing freehubs" on the internet for some tutorials.

I hope that wouldn't cost too much to do. This bike was bought used for $200 from my LBS and it looked pretty new when I got it, but I just spent $90 on a new headset last year, plus other repairs before that. If the LBS quotes me too high a price for this problem, I think I'll just live with it as long as I can and then use the bike for parts. The bike is a Specialized Hardrock.

It's a straightforward job and shouldn't cost much. You need to talk to the dealer or mechanic get a quote and be sure to remind him that this is a bike you bought cheap to save money and don't wish to sink much into.

IMO you should have made that clear when you needed the headset. Not that $90.00 is necessarily high depending on the headset, but there are less expensive headsets available and you didn't need to spend that much.

As far as living with it goes, it's a bad choice. I'm not one of those people that says "you're raking your life in your hands" but a non-engaging cassette can be a nasty surprise when you go to start pedaling after a descent, especially if you want to maintain momentum for an immediate climb which is common. Think Charlie Brown when Lucy yanks the football.

A Hardrock is a decent bike, and worth spending a bit to keep it going, just be sure your mechanic knows you have limits. OTOH don't fool yourself that a brand new bike won't also need service and you have to expect to spend on maintenance whatever you're riding.

That's good advice. BTW, the $90 for the headset job included the labor cost too. I'm really surprised a bike of this brand would keep having parts fail like this. I've done things to keep my bikes in as good of shape as possible, having learned from the past. I even had an axle break on a different bike, even though I never jump curbs anymore (knocks rims out of alignment). Yet when I used to jump curbs without a second thought in the past, I've never had a broken axle. It only happens when I actually take care of the bike. Go figure!