Cruzbike is definitely on the
Cruzbike is definitely on the correct path for an addition to a Cruzbike Silvio, Vendeta or Quest to convert it into a FWD MBB Tilting Delta trike in 10 minutes that handles like a 2 wheeled Cruzbike when moving fast.
A stable delta trike when going slower than 10 kph (6 mph) with the tilt lock fully or partly activated.
It is lighter than most trikes.
Has a more efficiency and much shorter drive train.
With a 550 mm (22") high seat it will be much easier to sit on, and especially climb off, compared to a normal trike with a seat 200 mm (8") off the ground, especially if you have crook knees and are slightly overweight.
Being at 550 mm seat height, the visibility to drivers will be the same as a DD bike.
You don't have to unclip at stop lights, so a much faster take off.
Three 700C racing wheels have much less rolling resistance than normal trike 16" or 20" wheels.
A tilting delta trike corners at 50% faster speeds than a tadpole trike, as seen on this video of Tim Hick's the Black Max. http://wn.com/2009_hpra_indy_recumbent_trike_ and with little tyre scrub and lost speed.
I think that the I Lean is the wrong arrangement, and a modified Black Max is the correct arrangement.
Following are the reasons why the I Lean tilting system has problems.
SCRUBBING the rear Tyre
http://cruzbike.com/fwd-mbb-delta-trike
Scroll down until you see the i Lean python delta trike with its BB crank, and especially the rear right hand tyre that is worn out due to scrubbing as the Centre Line of the front wheel cannot intersect with the rear two wheels as shown on.
http://www.hupi.org/HPeJ/0020/0020.html.
It is like the rear tyres on a tri axle semi trailer nearly being ripped sideways off the wheels when the semi does a tight U turn, as the trailer pivots around the front of three axles! The noise is like a nail being dragged across a blackboard.
TILT arms to allow for 45 degree lean
Another article on the i Lean suggests that the crank lengths be reduced to 90 mm down from 175 mm, to reduce the scrubbing.
All tilting trikes that I have seen on the internet, are designed to lean over to 45 degrees for fast tight corners i.e. 55kph on a 22 m radius corner, so the minimum tilt crank length is 150 mm for a 300 mm wide track, with the crank vertical.
It would be better with 160mm so the right wheel is always behind the front so that the brake and tilt lock cables do not get twisted.
Changing the cranks from 180 degrees separation to 90 will reduce the effective length but also lower the rear end 51 mm which would upset the bike steering geometry, and require the BB crank being raised 51 mm above the rear axle height. It is too short for the trike to lean over 45 degrees.
WEIGHT BALANCE for handling
Moving the BB crank pivot of the rear wheels approx. 300 mm aft of the existing rear axle, will reduce the TWO rear wheels with a 80 kg rider from 40 kg down to 15 kgs instead of 20 kg if the wheelbase is not changed.
Both Black Max (?? mm) and the Raptor trike (200 mm) have the rear wheels further aft.
Black Max had handling problems as the rear would loose traction on corners, as there was not enough weight on them. He was going to shorten the wheelbase to improve the handling, but has stopped updating his web site.
TORQUE induced into the rear stays due to impact loads
The TTrike reaction arm puts a vertical point load into the middle of the carbon Fibre rear stay of the Silvio which is NOT stiff in this plane and would bend it, which would then bend the rear upper seat stay strut.
The max deceleration due to the rear brake is 0.1 g before rear tyre skidding, so the design disc brake torque would be approx. 42 n.m. and this is the only torque the Silvio V2.0 onwards rear stays would be designed for.
By moving the centre of the two rear wheels approx. 300 mm aft of the existing axle location, the torque on the rear suspension when hitting a sunken water main manhole cover (600mm dia. So both rear wheels drop) and 3 G acceleration creates 40 kg*9.83*3*0.3 = 354 n.m torque around the old rear axle location.
This is 354/42 = 8.4 times the design disc brake torque and I think the rear stays will collapse.
One option is to extend the torque arm to the main frame, so it takes the torque reaction, OR move the wheels so the two wheels pivot point is in line with the old rear axle.
Instability under braking
At maximum braking when the rear wheel(s) lift off the ground, using the front brake only, 0.66 g deceleration can be achieved, with 280 n.m disk or rim brake torque.
If breaking hard with the front brake at 0.5 g, then the load on the two rear wheels drops from 35 kg/ 2 wheels down to (1-.5/.66)*35 = 8.4 kg/ 2 wheels.
If the rear brakes are applied at 40 n.m, then the front (left)of the two rear wheels will lift the rear of the trike 40/0.16 = 250 n (25 kg.f) uplift, so only the left wheel touches the ground, and the right is in the air.
This will tip the trike over sideways!!!
I think this is why I have only seen I Lean trikes with NO rear brakes.
Proposed alternative to I Lean is a modified Black Max with the two wheels in line with the existing rear axle
https://web.archive.org/web/20130801105546/http://fleettrikes.com/
The Rapto Trike is a refined version of the Black Max racing trike, but the Black Max has been well documented, even with his failures, and both are more refined and geometrically correct compared to the iLean (TTrike).
Two 140 mm disc braked wheels of the Black Max are 720 gm lighter than the Sturmey Archer 70 mm drum braked wheels of the Raptor.
Both should be quick release wheels.
The Raptor uses a 70mm drum brake? as the tilt lock and central pivot which is innovative.
The Black Max uses a 1" steerer stem as the central pivot, which is longer than needed to use the threaded end and the thicker end for the bottom bearing.
This could be replaced with a much shorter 25.4 mm hollow tube, so the tilting SHS beam is closer to the wheel CL to reduce bending moments.
The solid M12 axle bolt needs to be replaced with a hollow M15 quick release through bolt.
The solid M12 wheel tilt bolt needs to be replaced with a hollow 19 mm od hollow shaft with impregnated plastic bushes.
The brakes and parallel link posts should be vertical up, instead vertical down to reduce air drag, and make storage in the back of a car without the quick release wheels easier and more compact.
I apologize for being negative about the i Lean system, but it has the chance of hurting someone due to the braking lifting one rear wheel.
