Home Page

Cart, contains 0 items

When autocomplete results are available use up and down arrows to review and enter to select. Touch device users, explore by touch or with swipe gestures.
Expert Help
Earn Rewards
  • Just In
  • Learn

FSA
OS-99 CSI Stem

Be the first to review

Out of Stock

Don't worry though, we have a lot more Road Stems in stock than that.

Shop Similar Products

OS-99 CSI Stem

The 20-words-or-less summary is easy to do: The FSA OS-99 CSI stem is an FSA OS-99 stem wrapped in carbon fiber. But there are nuances to it that require elaboration: For starters, this is different than most other wrapped carbon fiber stems we've seen. It's much lighter than those stems. For the older wrapped stems, manufacturers were generally taking their heaviest stem, wrapping some cloth around it and clear coating the thing. But the carbon fiber wrap on the OS-99 CSI is actually doing something. It's structural.


The CSI acronym stands for Carbon Structural Integration. It is designed to stiffen up a really light stem (it adds 20g in weight in comparison to the standard OS-99). A stiffer stem is a more durable stem. This isn't to suggest that the OS-99 is weak. It isn't, and maybe some people won't notice the difference between the two stems, but if you're a bigger rider, or want some more bling on the bike, this is a great way to do it.


We suspect CSI is a technology FSA will use more and more of in the future. It's already being used in the aerospace industry. The basic idea seems to be going around the bike industry some. Shimano has an super-light clincher wheelset that bulks up an ultra-lean aluminum rim with carbon fiber.


The FSA OS-99 CSI Stem is a forged and CNC'd aluminum stem wrapped in carbon for extra stiffness. The aluminum base is AL7050. A gloss carbon is wrapped on top of the aluminum. There is a four-bolt sculpted face clamp. The clamp is anodized black. The four faceplate bolts and two steerer pinch bolts are made from titanium. The stack height of the stem is 41mm. The stem angle is plus or minus (+/-) 6 degrees aka 84/96-degrees. The stem comes in 80-130mm lengths in 10mm increments. The finish comes in either Gloss 3K Weave or Gloss UD. Weight is 118g.


Material
aluminum, carbon fiber
Length
80mm, 90mm, 100mm, 110mm, 120mm, 130mm
Rise
#ERROR!
Clamp Diameter
31.8mm
Steer Tube Diameter
1-1/8in
Recommended Use
road cycling, cyclocross

What do you think about this product?

View

Selecting an option will reload the available reviews on the page

Sorry, we don’t currently have any of those types of reviews for this product.