This SRAM Plasma derailleur is one of the DI.R.T. designs that SRAM inherited from Sachs.

DI.R.T. (note the weird placing of the full stops) stands for DIrect Response Technology. The DI.R.T. designs were extremely innovative, with two composite knuckles, a composite outer parallelogram plate and a composite inner pulley cage plate. That's a lot of composite for the time, and it made these derailleurs fiendishly light. They also had a pretty straight cable run and a groovy curvaceous look. Finally they were Shimano compatible - which gave SRAM something to offer the majority of the market, while it gradually built the population of riders using its proprietary 1:1 actuation.

Did they change gear well? I would say that they did - although many home mechanics, who were not used to the straight outer cable run, were not careful enough about the length of outer cable required. Get this right and these gears worked well, possibly very, very, well. Get it wrong and they were dogs.

Were they a commercial success? Possibly not. They acquired a reputation for being fragile, with numerous macho dudes claiming on the, then newly fashionable, internet that they had smashed their DI.R.T. derailleurs to pieces in this way or that. I have to say that I didn't notice more smashed DI.R.T. derailleurs than smashed Shimano derailleurs, so I am mildly dubious about this claim. I do think that the DI.R.T. derailleurs looked fragile, and that plastic and pressed aluminium possibly does not look as comforting as polished or anodised aluminium forgings.

Most of all these derailleurs were not cheap (particularly the higher end ones). The biggest downside of the DI.R.T. derailleurs was that it was hard to convince customers that a plastic and pressed aluminium derailleur was a luxury item that should cost as much as one constructed of polished or anodised aluminium forgings. These derailleurs were no only light in weight, they were also light on Bling.

Despite this history, and despite the fact that it does not chime with SRAM's foundation myth, it might be true to say that there is more of the Sachs DI.R.T. DNA in, say, a SRAM X-0, than DNA from SRAM's own, contemporary, SRAM ESP 900.

This is a lovely example of a SRAM Plasma. I think it is a relatively early version.

The SRAM Plasma was the top model in the SRAM DI.R.T. range. It weighed in at an impressive 199g and featured:

• an aluminium inner parallelogram plate.
• an allen cable clamp bolt
• an aluminium outer pulley cage plate
• an aluminium b-pivot bolt
• a fully dissassemblable parallelogram that could be readily cleaned and serviced
• a tension pulley with a sealed bearing, a guide pulley that has float and both are a soft pastel orange colour
• the words 'SRAM Plasma', prominently written on the b-knuckle
• a round badge on the p-knuckle to indicate the first letter of the model
• adjustment screws that can be turned with an Allen key or a flat bladed screwdriver
• both the pulleys are branded 'Sachs'
• an outer pulley cage plate that is branded 'Sachs' and 'DI.R.T.'.

That's quite a lot of Sachs branding for a SRAM product. Note also that the pulley wheels are branded 'Sachs', but I don't know of a Sachs derailleur with orange pulley wheels - so these must have been manufactured specially for this derailleur.

• Derailleur brands: SRAM
• Categories: SRAM - DI.R.T.
• Themes: Ultra-lightweight - touring/mountain bike
• Country: USA, manufactured in France
• Date of introduction: 1998?
• Date of this example: possibly 1998 (inner cage stamped X8)
• Model no.: unknown
• Weight: 199g
• Maximum cog: 32 teeth
• Total capacity: 40 teeth
• Pulley centre to centre: 86mm
• Index compatibility: 7/8/9 speed
• Chain width: 3/32”
• Logic: top normal
• B pivot: unsprung
• P pivot: sprung
• Materials: largely composite with an aluminium inner parallelogram plate and outer pulley cage plate