Installation manual

23 Copyright©SRAMCorporation•2009

FRAME PREPARATION

IMPORTANT:

The following sections on Frame Preparation call for making permanent and non-reversible modiﬁcations to your frame, requiring

advanced mechanical knowledge, skills, and tools. We recommend these procedures only be performed by a qualiﬁed bicycle

mechanic. If you choose to perform these procedures yourself you should read and understand these instructions and have a

working knowledge of tools required prior to starting work on your frame. In addition, you should wear your safety glasses until you

have completed all the steps in this manual.

FRAME PREPARATION - PART 1

Now that you have determined that the ISCG tabs on your frame are compatible with HammerSchmidt, it is time to make sure the

face of the bottom bracket shell and ISCG mounting surfaces are parallel and uniform. This is a critical process because one part

of the HammerSchmidt mechanism is located off the bottom bracket shell while the other part is located off the ISCG tabs. When

they are mated together, the HammerSchmidt internals need to be aligned so they can engage and function properly. Let’s get

started:

Make sure your frame’s bottom bracket shell threads are clean and undamaged; there should be no paint or dirt in there. For best

results, have your bottom bracket shell tapped by a professional bicycle mechanic.

Step 1:

Measure your bottom bracket shell width with a pair of digital

calipers. The shell width should be either 68, 73 or 83 mm

(+0.3 / -0.2 mm).

Step 2:

Face the bottom bracket shell. This will create a ﬂat surface for

ISCG cutter to bottom out on in the next step. Keep in mind the

tolerances as you face the bottom bracket shell. If the shell width

exceeds the maximum tolerance value (+0.3 mm), you will need to

face it within speciﬁcation. However, do not face shorter than the

minimum tolerance value allows (-0.2 mm). Follow the instructions

provided by the manufacturer of your bottom bracket facing tool for

proper operation of the tool.

68, 73, or 83 mm

FRAME PREPARATION