Last year I bought a Giant Defy 2. However, I didn't want to ride it through all the mud and salt in the winter months, so decided to buy a cheap bike to use in winter. I did quite a bit of research and decided to get a Decathlon Triban 500 SE. There is a more detailed review of the Triban 500SE road.cc .
I had to go into Decathlon with my daughter to buy some skiing equipment and had chance to look at the 500SE. It seemed to be a decent bike for the price and I had read several positive reviews. I ended up coming out of the store with one.
After a few local rides of between 20 and 40 miles I was quite impressed. The microshift gears (3x8) weren't as smooth a the Tiagra on the Giant, but changes were positive with no missed gears. I have got used to a compact gear set on the Giant, which I prefer to the more traditional three front rings. However, there isn't anything around here that's steep enough for me to need the small front ring, so it wasn't really a problem. The saddle was a bit uncomfortable after a couple of hours riding. However, it can't be that bad as I have a better spare saddle at home and I haven't bothered changing it yet! The carbon fork absorbs road vibrations nicely. The brakes do their job of stopping you with minimum fuss, but I needed to pull a bit harder than on the Giant.
I did change the tyres for Schwalbe Durano Plus folding tyres, as most of my riding is along country lanes, where punctures from hedge cuttings are common.
Having ridden it for a couple of months the freewheel packed up about 5 miles from home. I had to call out International Rescue and put the bike in the boot of the car. Decathlon didn't have any freewheels in stock, so gave me a complete new wheel. Definitely excellent customer service. They showed me the broken freewheel which had rusted and the bearings were badly worn on the drive side. I wash my bike after every ride in the winter and am careful not to get detergent or GT85 anywhere near bearings.
After 1500 miles the gears began to skip. Measuring the chain it didn't appear unduly worn. However, the teeth on the cassette looked just like sharks teeth! My LBS replaced the cassette and chain, plus the cables.
So what's the final verdict. Overall I am happy with the Triban. I enjoy riding it and I don't worry too much it getting plastered in muck and grit. For the price it's a good buy, but don't expect the drive chain to be as durable as a more expensive bike.