Mel Ivey can be contacted at mel.ivey@bikemotive.com
Bikemotive is based in southern Oregon. Two years ago at interbike 2011, he stated he was working on a BB-drive that had some unique features which he felt would solve some of the issues of existing systems. The fast-and-easy method right now is to install a freewheeling crankset with a flanged freewheel on the right side that holds two chainrings. One chainring is powered by the motor, and the other chainring drives the chain to the rear wheel (see: GNG, Cyclone, AFT, etc).
When power is applied or eased off, the motor torque applies some loading to the freewheel that is slightly off-center, since the freewheel is in-between the two spaced chainrings. The freewheels were not designed for this, so they wear out faster than when they are used with a single in-line chain. The flanged freewheels that are best known in this application are the White-Industries $60 ENO, and the more affordable $18 ACS-Crossfire. White Industries has claimed they "might" develop a dual-bearing freewheel that could handle side-loading better, but they have yet to produce those.
Mel wanted to develop a drive that allows the rider to retain the front 3-chainring cluster. Bikemotives new system uses a conventional chainring cluster on the right side, which allows one, two, and even three chainrings, and it should have no difficulty integrating onto a full-suspension frame. This provides several intriguing options.
If you want to develop a non-hub BB-drive that uses a de-spoked hub-motor, you can attach a readily-available 15T-22T track-cog to the left-side of a hub-motor (onto the 6-hole disc brake flange), which will then drive the left-side freewheeling chainring. The pedals do NOT spin when the motor is running. Conhis makes a small-diameter narrow DD front hub (http://www.conhismotor.com/ProductShow.asp?id=92) if you prefer a quiet motor, the popular MAC/BPM would be noisier due to the planetary gears, but they are small-enough in diameter to fit a variety of frames.
By retaining the three front chainrings, you could also make a dual motor drive, with a near-silent sine-wave Direct-Drive (DD) hub on the rear wheel using a single-speed freewheel...and a non-hub BB-drive that still has three gears.
To create as many options as possible for builders, the left-side freewheeling crankset has optional spiders that use chainring mounts with a Bolt-Center-Diameter (BCD) of 104, 110, 144, 130mm. He also has spacers for 64-BCD and 74-BCD which a creative builder might be able to adapt to use to attach a chainring of that type to a flanged freewheel.
Since the motor drives a single chain that is in-line with the way that the freewheels are designed to hold them, they should last much longer and take more power than the same freewheels in a dual loaded chainring freewheel system.
http://bikemotive.myshopify.com/collections/all
Here is the freshly-posted you tube as proof of it workings.
http://www.youtube.com/watch?v=7hn7WcT0DcI&feature=c4-overview&list=UUvPtqfSnlRnktJ4Ue6kf-xA
[youtube]7hn7WcT0DcI[/youtube]
Here's the Sept, 2011 animation:
http://www.youtube.com/watch?v=B35qqQ_uHQk&list=UUvPtqfSnlRnktJ4Ue6kf-xA
[youtube]B35qqQ_uHQk[/youtube]
Bikemotive is based in southern Oregon. Two years ago at interbike 2011, he stated he was working on a BB-drive that had some unique features which he felt would solve some of the issues of existing systems. The fast-and-easy method right now is to install a freewheeling crankset with a flanged freewheel on the right side that holds two chainrings. One chainring is powered by the motor, and the other chainring drives the chain to the rear wheel (see: GNG, Cyclone, AFT, etc).
When power is applied or eased off, the motor torque applies some loading to the freewheel that is slightly off-center, since the freewheel is in-between the two spaced chainrings. The freewheels were not designed for this, so they wear out faster than when they are used with a single in-line chain. The flanged freewheels that are best known in this application are the White-Industries $60 ENO, and the more affordable $18 ACS-Crossfire. White Industries has claimed they "might" develop a dual-bearing freewheel that could handle side-loading better, but they have yet to produce those.
Mel wanted to develop a drive that allows the rider to retain the front 3-chainring cluster. Bikemotives new system uses a conventional chainring cluster on the right side, which allows one, two, and even three chainrings, and it should have no difficulty integrating onto a full-suspension frame. This provides several intriguing options.
If you want to develop a non-hub BB-drive that uses a de-spoked hub-motor, you can attach a readily-available 15T-22T track-cog to the left-side of a hub-motor (onto the 6-hole disc brake flange), which will then drive the left-side freewheeling chainring. The pedals do NOT spin when the motor is running. Conhis makes a small-diameter narrow DD front hub (http://www.conhismotor.com/ProductShow.asp?id=92) if you prefer a quiet motor, the popular MAC/BPM would be noisier due to the planetary gears, but they are small-enough in diameter to fit a variety of frames.
By retaining the three front chainrings, you could also make a dual motor drive, with a near-silent sine-wave Direct-Drive (DD) hub on the rear wheel using a single-speed freewheel...and a non-hub BB-drive that still has three gears.
To create as many options as possible for builders, the left-side freewheeling crankset has optional spiders that use chainring mounts with a Bolt-Center-Diameter (BCD) of 104, 110, 144, 130mm. He also has spacers for 64-BCD and 74-BCD which a creative builder might be able to adapt to use to attach a chainring of that type to a flanged freewheel.
Since the motor drives a single chain that is in-line with the way that the freewheels are designed to hold them, they should last much longer and take more power than the same freewheels in a dual loaded chainring freewheel system.
http://bikemotive.myshopify.com/collections/all
Here is the freshly-posted you tube as proof of it workings.
http://www.youtube.com/watch?v=7hn7WcT0DcI&feature=c4-overview&list=UUvPtqfSnlRnktJ4Ue6kf-xA
[youtube]7hn7WcT0DcI[/youtube]
Here's the Sept, 2011 animation:
http://www.youtube.com/watch?v=B35qqQ_uHQk&list=UUvPtqfSnlRnktJ4Ue6kf-xA
[youtube]B35qqQ_uHQk[/youtube]
