As promised, here are some pictures of the new prototype 2015 TubaTrailer chassis – so heads down for a technically leaning post …
The photos show the latest incarnation of InnerTuba’s TubaTrailer chassis developments – with generous design input from Nick Lobnitz of Carry Freedom.
Nick’s design suggestions have been fabricated superbly accurately, and in extra quick time, by Colin Stones of Bike Repairs Lancaster.
As you can see, the chassis design unusually incorporates a central hitch point above the TubaTrike’s drivewheel, with the trailer wheels set as far back as possible. This puts weight directly over the drivewheel, giving much needed traction.
The weight of the chassis (7.7kg), the jury-rigged flatbed (7.7kg), and the wheels (3.6Kg) totals some 19kg unladen. I am reckoning on no more than 40kg, absolute tops, for expedition touring – an anticipated 60kg of gross trailer weight.
I’m currently trialling the chassis with around 80kg of concrete blocks as a cargo…. so, 100kg in gross weight. That weighs more than me (just about) … and I’ve not broken it yet!!
The hitch point – a simple Carry freedom “Lollipop” elastomer is precisely located at top dead centre of the drivewheel, and is also laterally centred directly onto the tyre tread – this way the bulk of the trailer weight falls directly onto the tyre tread, via the spokes and axle.
The hitch framework replaces the rear pannier rack, and its 3 points of contact are 1 bolt on to the seatpost and 1 each either side of the quick release skewer – nicely triangulated with no adaptation to the TubaTrike itself.
This combination of chassis and hitch handles superbly in all terrains, the main 2 improvements over previous TubaTrailers being the central towing position which totally eliminates energy sapping pitch and roll of the trailer, and – really important this one – not losing drivewheel traction on steep wet road surfaces.
The drive tyre grips the road surface with absolute certainty – no slipping. What a welcome first!
The good folks of ICE Trikes have given the thumbs up to this likely proving to be a worthy, workable design for towing behind their lovely trike, the Trice Mini.
The yellow plywood trailer body (made with the time, skill, and support from Bob Deegan of Robert Deegan Harpsichords last summer) has now been modified to mount this new chassis….
So what next?
Well, the tradition with prototypes is to try and break them – in a dignified way!
In this instance that means hours and hours of riding on the safe, traffic free environment of the Salt Ayre Sports Centre Cycle track – itself a super facility.