Tubeless mountain bike tires certainly improve on their conventional counterparts, but could they perform even better? The OPTIS insert is claimed to help them do so, by serving as an inflatable alternative to foam-bodied tubeless tire inserts.
So first of all, if you're unfamiliar with the selling points of tubeless mountain bike tires, here are a few of them …
They're light, as no inner tube is required; they provide better handling, since there isn't an outer tire and an inner tube sliding against one another; they're self-sealing, if sealant is being used; and, because there's no tube to protect, they can be run at lower pressure for increased traction.
All of that having been said, even tubeless tires can still get "snake bite" pinch flats if the air pressure is too low. They can also pop off the rim when taking big hits, in a process known as "burping."
In order to keep these things from happening, some companies now offer closed-cell foam inserts that occupy part of the space inside the tire – they fill and firm up the bottom (rim side) of the tire, leaving the top (tread side) still air-filled.
As an added bonus, because of the pinch-flat and burp protection they provide, these inserts allow the remaining airspace inside the tire to be inflated to a lower pressure than would otherwise be possible, boosting traction. The inserts also keep the tire rideable enough to get home in the event of a puncture.
That brings us to the OPTIS (Odyssey Pneumatic Tire Insert System), made by Odyssey BMX.
The device fills the same part of the tire as a traditional insert, but instead of being made of "solid" foam, it takes the form of a nylon/TPU (thermoplastic polyurethane) inflatable tube. So yes, technically speaking, it is an inner tube for tubeless tires – just not a full inner tube.
Both it and the tire itself are inflated (separately) via a switchable two-way valve stem. And importantly, as the insert is inflated, it cinches towards the rim, it doesn't balloon out towards the tread.
Once inflated, the OPTIS reportedly offers the same features as a foam insert – no pinch flats, no burping, lower tire pressure, can still be used in the event of a tire puncture – but at 90 g (3.2 oz), it's considerably lighter.
Additionally, it's said to hold the tire's bead more securely to the rim, as the air pressure keeps the one pressed firmly into the other. According to the company, "Burping becomes almost impossible." In fact, the insert is also claimed to make the seating of tubeless tires much easier, as it pushes the bead into place as it gets inflated.
Should you be interested, the OPTIS insert is available now in 27.5- and 29-inch tire sizes, priced at US$89.99. It's demonstrated in the following video.
Potential buyers might also want to check out Schwalbe's similar Procore system.
Source: Odyssey BMX via BikeRadar
