Welcome to the
International Spline Interface Standard web site.
What is the best manufacturing method for the spindle?
The spindle can be easily machined or forged, depending upon the material. Machining can be quickly performed with a three-axis NC lathe. Alternatively, machining the spindle in a mill is also possible, although care must be taken in fixturing to assure the correct alignment of the spline ends. Some spindle materials may be forged, although the process must usually be accomplished using multiple forging steps.
The spindle designation number is the nominal
distance between the crank stops on the spindle. Since all the spindles in
the standard are symmetric about the BB shell mid-plane (theoretically the
frame centerline), one-half the spindle designation number is the distance
from the BB shell mid-plane to the drive-side crank stop on the bottom
bracket. By adding this number to the “chainline
offset” provided by the crankset manufacturer, you
can easily figure out the resulting chainline of
that particular crank assembled onto any
It is up to you. The outside and inside diameter of the spline shape was determined so as to make use of as much existing tooling as possible in the industry. Bearings for this bottom bracket may take any number of forms, including custom cartridge bearings, needle bearings, bushings, or loose balls. The purpose of this standard is not to standardize one particular bottom bracket design, but rather to standardize the interface between the bottom bracket and crank. It is up to the individual designer to determine the type and configuration of bearings in the bottom bracket.
This will depend on how the crankset manufacturer designed their crank. We have found that grease helps to ensure the cranks contact the stops on the spindle, thus reducing the possibility of the crank loosening while riding. Further, the use of grease helps to eliminate noise that sometimes exists in interfaces. The drawback of using grease on almost any interface is that it reduces the friction present between the mating surfaces, thus reducing the amount of load transfer through friction. Please refer to the instructions from your crankset manufacturer regarding the use of grease on the interface.
Although at first it looks difficult to manufacture the spline shape in the crankarm, the quickest and easiest method is the same used for manufacturing the majority of tapered square cranks: a broaching operation followed by one or two coining operations. The broaching operation creates the straight-sided spline shape in the crank while the coining operation creates the 1° taper of the spline flute. The depth that the coining tool is pushed into the crank determines the amount of pre-load between the crank and spindle.
This depends upon your crank material. For most aluminum alloys we have found a pre-load of 3-5mm is ideal (as measured according to drawing sheet three). The individual crankset manufacturer will have to determine their required pre-load for themselves, based on analysis and testing.
If a crankarm has too much pre-load it will not bottom out against the crank stop on the spindle when initially installed. This will lead to the crank arm “walking” up the taper during some initial rides and a consequent loosening of the crank bolt. If the bolt is not constantly tightened until the crank finally contacts the stop, the result could be the crank falling off while riding or damage to the interface.
If the crankarm has too little pre-load it will bottom out on the crank stop prior to attaining a press-fit with the spindle. Depending on the magnitude of the press-fit, this may result in anything from a slight reduction in the load carrying capability of the interface to a “sloppy” fit between the crank and bottom bracket. This may also lead to creaking of the interface due to the slightly “sloppy” fit between crank and spindle.
We haven’t tried but don’t see a reason why it wouldn’t work. It is up to the manufacturer of such a crank to determine the interface’s suitability through appropriate testing.
A bicycle is used in many different ways, from
leisure riding around the block to radical 30-foot drop-offs. Each riding
applications places different requirements on the crankset
and bottom bracket. Thus, we included two bolt sizes in this standard to
allow manufacturers and riders to choose the best
Please consult the bottom bracket manufacturer to determine which bolt size is appropriate for your riding application. We cannot generally say that the M12 bolt size will produce a stronger spindle than the M15 because different materials may be used for the spindle. The bottom bracket manufacturer is in the best position to help you pick the correct bolt.
Yes, we recommend always using a washer
between the bolt and crank to prevent excessive deformation and wear. Please
only use a washer specifically designed for the
Again, please refer to the bolt manufacturer’s specification on the magnitude of the install torque.
Master Gage Questions:_________________________________
The spindle master gage is essentially a
“perfect crank” that slips onto the spindle. This “perfect crank” contains
GO/NO-GO indicators that allow the determination of whether the flute
geometry is within the tolerances required by the
Like the spindle master gage, the crank master gage is essentially a “perfect spindle” that fits into the crank and contains measurement lines allowing the determination of the amount of pre-load for the crank. This tool does not measure the shape of the splines in the crank it only gives an indication of the magnitude of pre-load the crank possesses. This tool is double ended, so manufacturers can press GO/NO-GO stops onto the tool and thus have a GO/NO-GO tool for determining whether the pre-load is within their required range.
Currently Race Face will be manufacturing the spindle master gage and Chris King will be manufacturing the crank master gage. Please refer to the Tooling page on this site for more information.
Of course, though they are most useful for
manufacturers of the
Not that we know of.
Not that we know of. We have performed several
patent searches worldwide and have been unable to locate any patents that may
be infringed by the
Yep, use it to your heart’s content.