What a beautiful ranch, what a fun event. Thanks to Chris Rothe and EcoBikeAdventures for hosting a party for us bike geeks. We had 15kW hubs, high power mid drives, home built, professional built, barely built bikes out to race. Lots of speed and nobody died; it was a good day.
A winter of hard work brings an update to the Tangent drive unit. New tooth profile, larger bearings, lighter gears and stiffer output cage, higher kV motors. What you'll notice is less sound and half the motor heat generated for the same power output.
Our new eccentric gears are only 40% the weight of the old design and utilize bearings that are twice the strength. All Tangent gearboxes will utilize the same 40:1 ratio and all motor sizes will be wound for 225kV. Lowering the turn count of the motor allows for larger wire and lower electrical resistance (hence, less heat). We're compensating for the increase in motor RPM with a bump in the overall reduction ratio. Starting with a 40:1 gearbox, ratios at the crankset between 44:1 and 95:1 are easily achieved through commonly available freewheels and chainrings.
- 5kW Tangent (detuned)
- 8spd internal transmission
- 190ft-lbs wheel torque @ 15mph
- 62ft-lbs wheel torque @ 45mph
- 51lbs pictured
- Cane Creek Double Barrel rear, Marzocchi 888 Titanium front, Shimano Saint stoppers, Chris King hubs, Maxxis DHF rubber, Carbon Race Face bars
Only one of the 3 cogs is used, that's just the back end of a standard cassette for more stability than a stamped sprocket. Wanted that 32t cog to lower the gearing and this is an easy way to get it. It rides like a dream, as if the back tire isn't there. Whatever you hit, the bike doesn't slow down. And it's unflappable under power, it doesn't squirm or squat under throttle due to the high pivot design. The IGH is in the frame so all the mass is as centralized as possible. It is so reactive. It is heavy for a bicycle, but it's also stable at speed and it's not too heavy. It turns every trail into a pump track, whether you're going up or down. The front remains light and can easily be lifted by motor power alone through 3rd gear (25mph) and with a tug it comes up while seated through 5th gear. The pedals work fine too.
Where would such a monster compete? Eco Bike Adventures is generous enough to host the first open class ebike race among the amazing trails in Northern Cali. 15 miles of amazing racing, Good luck fellow racers, this bike is faaaaast.
The new adapters extend the lines of the housing and re-use the side plate and rubber gasket in the same manner. One drive unit can now be swapped between 68, 73, 83 and 100mm BB widths.
Our final production version of Tangent drive, raw on raw. The HV80 is mounted cleanly on the left side, using the width of our new 6mm thick mounting plates to easily clear the crank arm and frame tube. The thicker plates are lighter and allow the use of rubber motor mounts, seen in black between the housing and mount. A revised chainline moves the motor chain to the inner position, eliminating twist and flex. The 951 frame uses the medium length metal downtube strap and was easy to bend to this frame's triangle shape; three lengths of strap are included in the kit.
Final assembly and test fitting of Tangent's first race motor. What makes this a race motor? Well, nothing actually, all our drive units are built to race. But this one is going to our first semi-officially sponsored racer. Good luck Kyle.
The initial shipment of customer drives has been a success, but we're not stopping with good enough. Let's see what's been improved in the last 4 weeks...
-improved chainline. The drive has been shifted within the mounts so the motor chain uses the inner chainring position. More adaptability as the small sprocket is in the correct position (some frame shapes don't allow large sprockets on the inside) and our torque is transferred more efficiently to the pedal spindle since the force is closer to the mount support.
-improved mounting design. New aluminum mount plates are lighter and stiffer than the previous steel and upgraded bolt pattern on the motor side remove all signs of torque twist. These mounts don't need to clamp to a frame tube- the interface is now a cushioned polyurethane tube and adjustable metal straps to hold the drive in place. The metal straps fit tube diameters from 1.25"-2.5"+ and are bent by hand to fit any tube shape needed.
-rubber motor mounts. Isolating the drive housing from the mounting plates removes all frame resonance and dampens high RPM gear noises. Compared to the previous non-isolated drives, the new design is nearly silent.
-upgraded chain tensioner. Riding on a sealed ball bearing pivot, the new tensioner encloses the spring and bearing within the Delrin tensioner, protecting them from the elements and ensuring the tensioner pivots no matter how much dirt you pack into it.
-custom oil seals. Special seals are being molded just for the Ascent to extend the service interval.
-patent-pending oil channels. Inside the unit we've designed a new way to pump our precious grease around the gear faces and carrier pins using only the movement of the cycloid gears and our special tooth geometry. Increased efficiency and longevity should be the result.
-new ESC mounting plate/heatsink. The HV80 is now suspended between the two mounting plates on a custom aluminum heatsink. Access to wiring connectors is very easy and the setup is very clean. The ESC will be joined to the heatsink via thermal compound, increasing the heat transfer capability of the HV80 immensely.
With little fuss, the trusted Kona retired to the corner yesterday, its drive transplanted oh so easily into a beautiful raw Intense Tracer 275 from the great crew at GHYbikes in Renton. The Shimano drivetrain performed flawlessly during today's messy test ride at Hansen Ridge (http://www.trailforks.com/trails/hansen-ridge/) despite our test rider's innate ability to hit every 6" boulder in the trail while under motor power.
16Ah of Turnigy Multistar provided 20 total miles with maybe 4000' vertical climb, after blowing past the turn on the fire road led me half way down the mountain before turning around. The VPP suspension of the Tracer responds very favorably to the torque of the Tangent drive and the bike leaps forward the instant the freewheels catch. Uphill boulder fields were easily dispatched in the 3-4th cog (34t front) with no pedal assist and enough torque in reserve to pick a line and attack it. The Tracer and its driveline were solid enough to lift the front over groups of big square edge rocks and pound the back through under power without a second thought.