CompleteStreets

I've had the same bicycle for the last ten years. It's a GT mountain bike. I've used it mostly for transportation on city streets. So far the following repairs have been made to the bike, mostly by me:

-replaced bottom bracket
-replaced chain
-replaced cables
-replaced tires
-replaced broken shimano shifter

Pretty much everything else is original.

As the bike gets older I just want to be proactive about any maintenance that could impact safety. In particular I'm wondering about the following:

1) Should I mess around with the bearings/hub of the wheels? If I put this off further, am I risking my safety?

2) Derailleurs - As far as I know, no maintenance has ever been done to the front or rear derailleur, other than adjusting cable tension and maybe applying lube to the springs on a few occasions. I'm still able to shift, although the front sprockets don't shift as smoothly as I'd like. Will anything bad happen if I don't replace the derailleurs? If I keep the original derailleurs, what should I do to make the front derailleur function more smoothly?

3) Frame - It's aluminum. GT's patented "triple triangle" setup. There are a few nicks to the frame, but nothing I would consider a dent. Is the frame at risk of cracking due to being ten years old? What should I look for?

4) Cassettes - Amazingly, the teeth on the cassettes are in quite good shape. Not much rounding of the teeth that I can see. I believe I've biked 10,000 miles on the bike, but it could be anywhere from 7,000 to 13,000 miles. I attribute the minimal wear to the fact that I don't grind my gears and I take things relatively easy. Other than the teeth of the cassettes, is there anything I should look at to determine if it's dangerous to keep the original cassettes?

5) Front shocks - they are pretty much shot, but I'm so used to them being the way they are, that I'm not bothered by this. Any safety issues to consider?

6) Anything else I should evaluate to verify that the bike is safe to ride for the next few years?

Thanks for your help with any of my questions!

Raging_Bulls

Seeing as I don't know when all that work was done, I'll assume it has been done "over the years" rather than recently. Here's my €0.02

1 ) A good trick would be to remove the wheels and turn the axle. If it feels metallic or rough rather than smooth, you may want to re-grease them before the balls start damaging the cups. Not too dangerous when that happens, but it can be rather expensive to fix if you let it get that far.

2 ) My first idea would be to check out the cables. Any rust, kinks, etc? A new outer and inner cable can do miracles, but sometimes the shifter or the derailleur itself may need some oil to smooth things up again. Or maybe the cable has stretched a bit and it needs a bit of adjusting.

3 ) I wouldn't worry about the structural integrity of a 10 year old aluminium GT frame. There are plenty of Zaskars, Panteras etc that are twice as old (or even older) and have seen extensive offroad use. They really are strong.

4 ) Be sure to check the chain for stretch. Plenty of manuals on how to measure it. That'll tell you more than looking at the cassette itself.

5 ) Your call. If they are stuck, it'll be like a rigid bike. No need to worry about them falling apart or dropping so far that you suddenly lose control over the bike, stuff like that happens so rarely that you actually have more chance of being hit by a meteor while on the bike.

6 ) Check the tires and brake pads. Bulges in the sidewalls, deep cracks, any signs of carcass damage or rubber deterioration really. Also check the brake cables for rust and make sure the outer cables are kink-free and don't have cracks or tears in them.

RubeRad

Sounds to me like you've got a pretty good handle of what's going on. Here are my thoughts, others may chime in as well:

1. It would not hurt to open/clean/repack your wheel hubs with fresh grease; but if they seem to be spinning well, it probably isn't super necessary either. No risk of danger that I can think of; wheels would tend to have gradually growing friction, not sudden catastrophic failure.

2. Derailleurs. Good to keep pivots lubed. Also you may consider taking the pulleys out of the RD (be careful, they are different, and hard to tell apart!), clean them out, put some fresh grease in, and put the pulleys back in. Again, no safety risk here, just risk of poor shifting. I guess perhaps if you need a quick downshift for an emergency manoeuver there could be a risk?

2.5. Front derailleur: perhaps you need new chainring(s), or at least FD adjustment. Counterintuitively, a FD is harder to dial in than a RD. But again, not a safety issue, just a suboptimal-shifting issue.

3. Frame. I wouldn't worry about it. GT is a reputable brand, MTB are generally overbuilt, so your frame should last for decades (many given your 'take it easy' riding style)

4. Cassette: it is possible for cassettes to be difficult to diagnose by eye, but the bottom line is, if it shifts well enough for you, then it's fine. Can't think of any safety issue.

5. Shocks: As long as you are riding easy, it shouldn't be a problem. For street riding, most prefer to "lock-out" their shocks anyways. If you are not riding rough trails that can take advantage of a front suspension, you might consider getting a rigid fork instead.

6. First thing I can think of is tires. But even then, if they're not showing thread, and if they are not dryrotted, or completely full of cracks (some cracking is ok), you're probably good. For street riding, you should look into "city tires" or possibly even fully slick tires, you will get a noticeable speedup over knobbies.

bradtx

CS, Reads like a good time for an overhaul.

I'd add replacing rim strips, in particular if plastic.

Brad

CompleteStreets

Raging_Bulls and RubeRad, thanks so much for the detailed responses! bradtx, I believe a replaced the rim strips a few years back, but I'll keep that in mind the next time I have to remove a tire.

You've given me the confidence to continue riding my bike into the foreseeable future. I do think I'll be cleaning and regreasing the wheel hubs, and I'll address my front derailleur at some point. I replaced my tires about a year ago. Funny you mentioned getting "slick" tires. My current tires are 1.6" slicks, which I got in order to allow enough clearance for adding fenders.

I do have one follow-up question:

Regarding the front shocks … when I hit a bump, the shocks compress quite a bit and are fairly slow to retract back into the normal position. They also make a squeaky sound. I'd almost prefer to make the shocks completed rigid, partly so I can add a front basket. Is there a way I can adjust the shocks so they don't "give," or would I need to replace the whole fork? Thanks!

Tim_Iowa

If your fork has a lockout function, then that will keep it from compressing. But most older suspension forks didn't have lockout.

As you realize, you'd be better off with a lighter, rigid fork. To do this, you'd have to find a fork with a similar axle-to-fork crown measurement. Google how to measure. Also check the steerer size (hopefully it's a 1" quill) and steerer length.

Find a rigid fork with the same steerer size, axle to crown measurement, and steerer length. If you have a bike co-op in your town, they probably have a bin of rigid forks for you to peruse.

There are several other threads on these forums with more answers on converting suspension to rigid, you should search.

Re-packing and adjusting the hubs is pretty easy and will definitely extend the life of your wheels.

RubeRad

Yes, try to lockout your existing fork if possible, if you want to keep it suspension it is possible to open the fork and replace the suspension element (probably an elastomer=spring), if you want rigid, I wouldn't worry so much about axle-to-crown, just make sure it's for the same size wheel (I assume MTB standard of 26"). And 10 years old is (like Tim_Iowa says), quite probably 1" quill, aka 1" "threaded", which will allow you to reuse your existing stem.

To repack hubs you will need "cone wrenches" of the appropriate size. Since cone wrenches by definition have to be quite thin, this is an area where you don't want to go cheap, as low-quality (soft) cone wrenches will be ruined after 1 or 2 jobs. Buy a quality (i.e. Park) pair of cone wrenches in your specific size (cheaper than a whole set of all possible sizes), or look for a local co-op with tools you can use.