Quick comparison:
| Fork | RST F1RST Air 24" | 28mm Rockshox SID |
|---|---|---|
| Axle to crown in 60mm mode | around 420mm | 430mm |
| Weight | 1600g | 1200-1300g |
| Brake mounts | v-brake and PM | v-brake and IS mount (adapter required for 24" v-brake use) |
| Price | $200-250 new | $50-100 used |
| Parts availability | Unknown - can't find a basic or full service kit online | Basic or full service kits still available (see RS SID service kits) |
| Travel adjustment | Unknown | Can adjust in 10mm increments using all-travel spacers. 50mm - 80mm travel easily available. Some SIDs can go to 100mm as well. |
Conclusion: get a SID...
The SID has a lot going for it over the RST F1rst:
- dual air spring - more tunable for light riders;
- lighter weight;
- cheaper;
- easier to maintain - readily available spare parts and full service manuals directly from SRAM;
- can be used on a 26" wheel bike later.
The RST F1rst does have some advantages:
- available new;
- will work straight out of the box with 24" v-brake rims.
However, working with 24" v-brake rims is not a huge advantage when you consider that for the money saved using a SID you can probably build a 24" disk front wheel to use with the SID (and not worry about making a special adapter bracket to get it to work with 24" rim brakes).