Worn Rear Cogs

[jackspratt]

I bought a mid-range Merida (>TBH10k) mountain bike in Udon last year.

I have subsequently ridden >1,200km, with about a 70/30% split on/off road.

I have recently been experiencing slipping of the chain, particularly when I put any real pressure on the pedals. From looking at the rear end, it seems that some of the teeth on the smallest and second smallest of the rear cogs have worn, causing the slipping.

The bike has never been serviced.

My question is (before I take it back to the bike shop) - should such wearing occur, given the use the bike has been put to?

[impulse]

I am in awe of someone that uses mostly the smallest cogs on the cassette. Being old and fat, I spend most of my limited km on the bigger wheels and a slower pace. And a lot of those on the electric motor, too.

I suspect you would get better life from the sprockets and chain if you cleaned and oiled up the chain occasionally. There are some threads about the best way to do this with stuff available in Thailand..

I once had a bike for 30 years with tens of thousands of miles on it, but I maintained it religiously because I was too poor (cheap actually) to replace the parts. It had the original components on it when I lost it, with the exception of tires, cables, brake pads, and a front wheel and fork I bent hitting a log. Nowadays, my free time is more valuable so I don't do the maintenance and the parts wear out faster. I'm okay with that.

I'd be happy with 1200 hard km.

Replace your chain when you replace the rear cassette. You may even have to replace the front chain wheels.

[fdimike]

Jack

Much depends on how well you maintained the bike. When you say the bike has not been serviced I take that to mean "at all" by neither you or a shop.

You can wear out a cassette and a chain very quickly unless you clean them both especially after riding in the dirt and then lube the chain with proper chain lube. The dirt mixes with the lube on the chain to create a grinding paste which then acts to destroy both the chain and cassette. It's much cheaper to learn how to properly clean both these things as well as your from chainrings instead of constantly replacing them. The other variables are the quality of the cassette and chain. I would bring the bike back to the shop and ask them to examine the cassette and the chain as I believe either one or both are worn.

I'n not sure where you bought the bike but I can recommend the bike shop downtown across from the newly renovated PTT station. The owner Peter speaks excellent english and is a cyclist as well. I have been a customer of his for nearly 7 years now. I normally buy my parts from him and maintain the bike myself.

[jackspratt]

Thanks for your responses, and confirmation of the problem.

fdm - yes bike is from the 5 crossroads shop. I am heading out of Thailand for a couple of weeks, so will drop the bike off with Peter on my way to the airport, and leave it with him until I get back.

Thanks also for the info re proper maintenance. I had only ever ridden bikes on-road before, so wasn't aware of the wear and tear from the red dirt up here.

I will try to do better.

[wantan]

Usually you can replace the smallest two or three rings of the rear casette separately. They wear out pretty quick if you use them much. But mostly they last longer than the chain.

So i guess you need to replace your chain. Especially if you never have oiled it since new

In future best would be to check the chain wear from time to time. A worn chain damages all other parts of the drive train. So you have to replace the chain when its worn over the limit.

There are many websites with info for this, e.g.:

http://en.wikibooks.org/wiki/Bicycles/Maintenance_and_Repair/Chains/Checking_chain_wear

http://cyclingtips.com.au/2009/03/how-to-check-for-chain-wear/

...

I have a special tool for this, the rohloff caliber. A bit expensive but you buy it once in your life and it provides a very easy way for chain wear check. So i like it. But for sure there are cheaper tools for this with same functionality.

[rebo]

Usually you can replace the smallest two or three rings of the rear casette separately. They wear out pretty quick if you use them much. But mostly they last longer than the chain.

So i guess you need to replace your chain. Especially if you never have oiled it since new

I have a special tool for this, the rohloff caliber. A bit expensive but you buy it once in your life and it provides a very easy way for chain wear check. So i like it. But for sure there are cheaper tools for this with same functionality.

Instead of a caliper I use a "just-worn-out" sample chain (Of course, years ago determined by a caliper ...) Everytime I maintain a chain (with master links to take them off) I compare the length with this sample. So I reach a life span of about 2'000 ... 3'000, sometimes almost 4'000 km per chain, and about 12'000 ... 15'000 per cassette, given maintainance intervalls of 300 ... 600 km, depending on kind of road I drove.

I clean my chains with Diesel and a tooth brush, blow them out with a compressor, and re-oil them with Chain Oil No. 5 (available here: N18 46 52.2 E98 59 37.7. I don't like this shop but it seems to be the only one importing my favorite chain oil). About 20 mins needed for that.

I try whatever possible not to drive in wet conditions.

[wantan]

I clean my chains with Diesel and a tooth brush, blow them out with a compressor, and re-oil them with Chain Oil No. 5 (available here: N18 46 52.2 E98 59 37.7. I don't like this shop but it seems to be the only one importing my favorite chain oil). About 20 mins needed for that.

Some like kerosine more because it doesn't have the diesel smell:

http://www.thaivisa.com/forum/topic/664398-chain-cleaner-liquid/

I try whatever possible not to drive in wet conditions.

But riding mountain bike without any dirt is a bit boring, isn't it?

I hate the dirt too, but its too much fun

[impulse]

I'm going to spark a controversy by recommending WD40 for cleaning the chain. It smells good and does a great job of cleaning the grunge.

But don't count on WD40 as your lubricant. My favorite lubricant for most light oil applications (fishing reels, tools, bike parts, etc) is sewing machine oil.

I have absolutely zero documentation that it's recommended by anyone else in the entire world.

But I used to visit garment factories in China and when I saw the abuse the sewing machines took, and the horrible dust and lint they tolerated, and saw that they kept on going 24/7 for months at a time, I was convinced.

Besides, sewing machine oil is extremely easy to find, and reasonably priced.

[fdimike]

Impulse

I'm a believer in kerosene as a cleaning agent. Remove the chain and dump it in a container of kerosene and all the grunge immediately fllas to the bottom. However, I had an unusual experience with Muc-Off Ceramic Dry lube. It is not soluble in kerosene or any other similar liquid. You have to use water to clean it off. It's definitely off my list of chain lube favorites.

Sewing machine oil is kind of thin isn't it? It must also attract a ton of dirt which would not be the same kind of conditions inside a garment factory. I think I'll stick with my Finish Line