Shimano Derailleur Tourney TX800 Rear 7/8 Speed Black

The Shimano RD-TX800 Tourney Rear Derailleur (7/8-speed, black) is an entry-level mountain/trekking rear derailleur designed for simple, reliable shifting on low to mid-range bikes.

Shimano Tourney RD-TX800 Rear Derailleur 7/8 Speed Black

What it is

This is:

• a rear derailleur for 7 or 8-speed drivetrains
• part of Shimano’s Tourney TX series
• designed for MTB, hybrid, and commuter bikes

It is Shimano’s most basic indexed MTB derailleur tier.

Key features

• Compatible with 7/8-speed SIS shifting
• Works with Shimano HG 6/7/8-speed chains
• Double Servo-Panta mechanism
  • improves chain tracking across the cassette
• 13T/13T pulleys
  • larger jockey wheels reduce noise and wear
• Supports up to:
  • 34T largest sprocket
  • 43T total capacity

What “capacity” means

Total capacity (43T) is how much chain slack the derailleur can handle across:

• front chainring differences
• rear cassette range

$\text{Total Capacity} = (\text{Largest front} - \text{Smallest front}) + (\text{Largest rear} - \text{Smallest rear})$

If exceeded, you may get:

• chain slap
• poor shifting
• inability to reach all gears safely

Ride feel

• Simple and predictable shifting
• Not very fast under load
• Designed for casual riding and commuting
• More tolerant of misadjustment than higher-end derailleurs

Best suited for

• commuter bikes
• school/utility bikes
• entry-level MTBs
• budget 7/8-speed setups

Pros

• very affordable
• easy to set up and maintain
• widely compatible with Shimano 7/8-speed systems
• durable enough for everyday riding

Trade-offs

• heavier and less precise than Altus/Acera/Deore
• slower shifting under pressure
• limited gearing range support
• basic bushings (not high-end bearings)

Bottom line

The Shimano RD-TX800 Tourney is a basic but reliable 7/8-speed rear derailleur built for simple bikes and casual riding, offering dependable shifting at low cost but without the precision, speed, or durability of Shimano’s higher-tier MTB groupsets.