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Google Review received from Quentin: Bike rack story. So I already had a 5 bike Shingleback bike carrier before we took delivery of our new van in March (JJOB 22.68.1). So I decided to get a bracket made up for the draw bar to mount the Shingleback on the drawbar. Last week, I decided to cough up and get the ISI bike rack fitted. OMG. What a difference it has made. It is like towing a new van. The guys at ISI were really helpful and they were keen to do the weights and measurements. When comparing my old Shingleback with 4bikes (one heavy ebike) with the drawbar bracket - the ISI set up is only 18kg lighter, but the ball weight measured 40kg lighter! That doesn’t sound like much of an improvement, but the handling of the van is transformed! No more see-sawing over every bump, no more bouncing! Today towing it (without the WD bars) - I can finally say “I didn’t know the van was behind me!” I kept checking my mirrors to make sure the van hadn’t fallen off! Another example and lesson for me - NOT to try and reinvent the wheel. |
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 iSi Response - Always happy to help Quentin. Your family can now enjoy relaxed travel with the confidence that the caravan will remain balanced, safe and secure, particularly in the event of an emergency swerving manoeuvre at speed.You're not the first to have experienced instability issues with vertical shuttle racks and unfortunately, people who don't reach out, needlessly accept that poor caravan towing dynamics is the price to pay for travel bikes on board. Whilst tow ball weight is important, the best possible towing dynamics has more to do with the position of the centre-of-mass of the loaded carrier in conjunction with a highly rigid carrier assembly that is tuned to caravan drawbar characteristics when under load. As you've now experienced, at iSi we engineer these solutions to position the centre of mass back towards the axle and at a height that is close to the roll-centre of the caravan. By moving the centre of mass back away from the tow ball towards the axle, a greater proportion of the dynamic lateral loads is taken up by the axle so that the tow point doesn't push the rear of the car around. The other part of the instability problems that you experienced was solved by eliminating the tall centre of mass positioned so close to the tow point. With all the bicycle supporting components well above head-height, vertical shuttle racks are notorious for a very tall centre of mass so as the trailer leans left or right, that tall mass creates a significant lateral load on the tow point. This steers the van left and right which in turn pushes the rear of the car left or right. Moreover, a vertical shuttle rack inherently has low rigidity, so it is regularly out of phase with the trailer. This amplifies the instability problems that you experienced and makes it impossible for modern vehicle and caravan stability control systems to function properly. To rectify your particular caravan, the process was to install a highly rigid yet light weight mounting system tuned to the deflections of the Jayco drawbar arms and to lower and position the centre of mass of the loaded bicycle carrier back close to the roll-centre of the caravan. This all but eliminated the lateral loads and trailer self-steer on the tow point. In doing so with a highly rigid assembly, the loads now remain in phase so that your VSC and ESC systems operate as intended. Moreover, as a carrier mounting system that is tuned to the drawbar characteristics under load, this will eliminate further notching damage to your drawbar arms. Over time you will discover other benefits with your new iSi carrier. You will find it easier and quicker to load and unload your bicycles. This solution also delivers a good deal more vehicle clearance compared to vertical shuttle racks so I'm sure that you will find added trailer articulation now, especially when backing the caravan into really tight camp spots. Your new iSi bicycle carrier will outlast you and me both Quentin, so do keep in mind the iSi BuyBack and Refresh programs to swap parts as your vehicle, caravan and cycling demands evolve over time. All the best Quentin. Safe and happy travels and please do keep in touch.
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But on a recent 6wk trip with full tanks (for a third of the journey) full food and clothes - the ball weight was on or slightly over the max ball weight, and towing it with our well set up Y62, I would have never said “I don’t know the van is behind me”. I felt every bump, dip and change in road texture, as the van seemed to see-saw constantly!! WD bars helped, but I still noticed the poor handling, I just assumed this is the way it would be - towing a fully loaded 3.1T van.
