can you show me the advantages of these two,to help me make a decision.

Carbon is lighter, which is very useful in a rim as it allows you to accelerate and change direction more quickly. Rim weight is the most important weight element of a bike.

The penalties of using carbon (apart from cost) are:
- Durability. Not such an issue with good ones, but cheap ones can have problems.
- Build quality. Carbon rims can be less "true" than alloys.
- Braking. The carbon surface requires special pads which generally wear out more quickly and don't stop you as fast. Carbon clinchers are particularly susceptible to overheating which leads to the rim failing. Either delamination (the carbon layers separate) or catastrophic failure. This is most likely during prolonged braking on long fast descents. Not fun! Edco osseous have used ceramic coatings to address this problem.

All of the above, and please use the search function of the forum. This is Weight Weenies. The topic has been discussed numerous times.

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