Quoted By:
>Contact points- grips, bartape, saddle, pedals
Always worth replacing when worn out, modifying to your taste, and upgrading to a high spec version. Make a huge difference to how nice a bike is to ride, and can be swapped between bikes.
>Consumables, chain, cassette, cables, brake pads, bearings
Refreshing these is probably the best improvement you can make to any bike. This is what should be focused on instead of 'upgrading' or 'modifying'
>Groupset, shifters, derailers, crankset
Almost never actually wear out and should almost never be replaced. Everything disatisfying about a groupset preformance is usually dirt, poor cassette/chain condition, a bent hanger, worn out cables, or poor setup. 'Upgrading' this doesn't make a real difference and is a waste of money and is a cope for poor skill in maintenance. The exception is that it's worth modifying a bike for wider range gears, but that can normally be done while keeping most of what you have.
>Wheels and tires
Wear items. Upgrading tires or changing the type of tire can make sense, but usually, just replace them when they wear out. Service wheels. Service bearings. True them. These both make a large difference to the ride of a bike.
>Repainting
never worth it except on high-spec steel frames with bad rust issues. Huge amount of work to do well and almost always gives a worse finish than factory and de-values a bike. Scratches etc are part of an old bikes charm. If you don't like the color of a bike sell it or don't buy it. If you want it to pop, clean it and wax it instead.
>Accessories- Fenders, racks, panniers, baskets, bells, bottle cages, bike ducks
Worth it
If you want to do a full custom project for reasons start with something high spec in terrible condition. Probably an older bike. Pouring money into an entry level shitter from decathalon is retarded. Pouring -time- servicing it and some money is sensible to learn and improve it, maybe even for the next person.
