Mounting system for an internal bicycle transmission
View Patent ↗A bicycle transmission assembly that is mountable to a bottom bracket shell of a bicycle frame. The bicycle transmission generally includes an input crank assembly, an output chainring, a planetary gear mechanism, a control system and a mounting system. The output chainring engages a bicycle drive chain that includes a plurality of chain links. The planetary gear mechanism includes a ring gear and provides a plurality of transmission paths. The planetary gear mechanism is mounted coaxially about the shell axis. The control system is operatively connected to the planetary gear mechanism for selecting one of the plurality of transmission paths. The mounting system mounts the planetary gear mechanism and the control system to the bottom bracket shell. At least one chain link overlaps the ring gear as viewed along the shell axis. The at least one chain link engages the output chainring.
1. A bicycle transmission assembly mountable to a bottom bracket shell of a bicycle frame, the bottom bracket shell having an axis, the bicycle transmission assembly comprising:
an input crank assembly;
an output chainring for engaging a bicycle drive chain including a plurality of chain links;
a planetary gear mechanism including a plurality of planet gears and a ring gear having teeth engaging the plurality of planet gears, the planetary gear mechanism mounted coaxially about the shell axis and providing a plurality of transmission paths;
a control system operatively connected to the planetary gear mechanism for selecting one of the plurality of transmission paths; and
a mounting system for mounting the planetary gear mechanism and the control system to the bottom bracket shell,
at least one chain link overlapping the teeth of the ring gear as viewed along the shell axis, the output chainring nonrotatably connected to the ring gear.
2. The bicycle transmission assembly of claim 1 , wherein the at least one chain link engages the output chainring.
3. The bicycle transmission assembly of claim 1 , wherein the control system is mounted coaxially about the shell axis.
4. The bicycle transmission assembly of claim 3 , wherein the planetary gear mechanism further includes a sun gear,
the plurality of planet gears operatively connected to the input crank assembly.
5. The bicycle transmission assembly of claim 4 , wherein the control system includes:
at least one sun pawl;
a collar providing a seat for the at least one sun pawl, the at least one sun pawl configured to be selectively positionable between an engaged position nonrotatably connecting the sun gear to the collar and a disengaged position allowing the sun gear to rotate relative to the collar; and
a shift actuator for selectively positioning the at least one sun pawl between the engaged and disengaged positions.
6. A bicycle transmission assembly mountable to a bottom bracket shell of a bicycle frame, the bottom bracket shell having an axis, the bicycle transmission assembly comprising:
an input crank assembly;
an output chainring engaged by a bicycle drive chain including a plurality of chain links, one of the engaged bicycle drive chain links having a radially innermost circumference forming a first radius with respect to the shell axis;
a planetary gear mechanism including a plurality of planet gears and a ring gear having a toothed profile engaging the plurality of planet gears, the toothed profile bounded by a peak and a base, the ring gear base forming a second radius with respect to the shell axis,
the planetary gear mechanism mounted coaxially about the shell axis and providing a plurality of transmission paths;
a control system operatively connected to the planetary gear mechanism for selecting one of the plurality of transmission paths; and
a mounting system for mounting the planetary gear mechanism and the control system to the bottom bracket shell,
the output chainring nonrotatably connected to the ring gear,
the first radius being one of equal to and less than the second radius.
7. The bicycle transmission assembly of claim 6 , wherein the control system is mounted coaxially about the shell axis.
8. The bicycle transmission assembly of claim 7 , wherein the planetary gear mechanism further includes a sun gear,
the plurality of planet gears operatively connected to the input crank assembly.
9. The bicycle transmission assembly of claim 8 , wherein the control system includes:
at least one sun pawl;
a collar providing a seat for the at least one sun pawl, the at least one sun pawl configured to be selectively positionable between an engaged position nonrotatably connecting the sun gear to the collar and a disengaged position allowing the sun gear to rotate relative to the collar; and
a shift actuator for selectively positioning the at least one sun pawl between the engaged and disengaged positions.