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Comment by protomyth | Hacker News Reader

I just have a tough time believing a belt is better than a chain, when I've had two cars with timing belts break before the suggested replacement mileage, but never had the problem with a timing chain. It seems like the same would be true of a bicycle.

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Chains are great if you drive a car to 125k miles and junk it, but I've recently started preferring belts since I try to make mine last 200.

Eventually the chain tensioners wear out and changing a chain is enough work that I usually scrap the car at that point. Belts are much easier to change, and perhaps more importantly, inspect.

Not to mention that a lot of chain-drive cars often choose cheaper or substandard materials for chain guides.

You end up with a choice between sounding like it's broken and having to spend a good chunk of a weekend dismantling it.

I've driven a lot of cars beyond that point where the chain guides don't exist... The sounds of a chain sloshing around are unmistakable :). If you're lucky it will skip a few teeth one day and give you a chance to fix it.

Unlucky, it skips a bunch of teeth and bends all the exhaust valves. I managed to salvage one of those too by driving around at high rpm until the valves had...Hammered themselves mostly straight again. Wouldn't recommend, usually you'll get an iffy cylinder or two after that that mysteriously only fire above 2000 rpm

I've owned 3 vehicles with cam chains. All of them have over 320,000 km (200k miles).

None of them have had issues with the chain or the tensioner.

That could be a testament to old Japanese engines (specifically Nissan) though, two from 1996 and one from 1982.

Chains on bicycles do break occasionally, and there are practical reasons why a belt is better, which is they don't need to be covered in black stain-your-pants-if-you-ever-touch-it grease.

Just to be the contrarian, the timing chain failed on my Saturn at 70k miles, and the engine was destroyed.

If a bike chain breaks, the bike isn't destroyed, though it could be hazardous if you're honking up a hill when it happens. But for the most part, chains wear out and you replace them.

In my view, the benefit of the belt is not lifetime, but the lack of oil, making it cleaner. With that said, I don't have a belt drive bike, but would consider it if I ever get a new bike.

A timing chain is wider, runs straight and most importantly is properly lubricated.

Also a timing belt lasts 100,000 miles and runs a lot faster than a bicyle belt.

You might want to rethink that 100,000 miles. I've noticed a lot of car manufactures (e.g. Kia) that recommend a change at 60,000. I would not ignore that recommendation.

Timing bits are considered emissions equipment. In California (and states that follow California requirements) this means a 150,000 mile warranty. Most manufacturers will thus specify a change interval that avoids warranty service. Some, like Mazda in the 90s, will use the same belt rated for 49-state compliant intervals and simply bump up the interval.

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