Mantis: Elegant home brewed TTS

Editor’s Note: The fact that several people are tinkering on their own with the TTS concept verifies two things. First, that tele is far from dead. Secondly, that the future of further progress in the telemark world will be found where the grass roots energy is flowering in spite of the lack of commercial development.

Mantis: a carbon fibre plate for integrating a telemark cable with a tech toe.

Designing the Mantis
Ever since learning to ski telemark, I have longed for a binding that skis well, is lightweight, has a true free pivot and sports some degree of safety release (allowing skis to come off in the event of an avalanche). The Telemark Tech System promises to meet these requirements. I designed the Mantis binding as a home project to take the TTS concept and to turn it into a binding that could be skied hard on fat skis without concerns about pulling the binding out of the ski.

The Mantis TTS w/Scarpa TX boot.

The Mantis is intended for use primarily in the backcountry, balancing the competing requirements for lightweight and robustness. The Mantis binding is a few grams heavier than the conventional TTS system but more robust in critical areas, reducing the chance of it breaking miles from the trail head. In addition the Mantis was designed to use the same hole pattern as the old (metal) NTN Freeride so that it can be swapped with the Freeride for in-bounds skiing to take advantage of the step in feature and brakes. This is achieved using inserts in the ski and allows the Mantis to be used as a dedicated backcountry / sidecountry tool.

Mantis TTS: not the lightest tele binding, hardly the heaviest.

Mantis’ Key Features
The final assembly of the Mantis weighs in at a respectable total 1.2 kg for both feet. This is about 200g (~7 oz.) heavier than a lightweight TTS system and significantly lighter than any conventional free pivot binding available at the time of writing (Jan. ’13). In addition to its light weight, the Mantis combines excellent skiing performance with true free pivot and a release.

Field Performance

Dropping in the steeps in the Alps on Mantis.

The Mantis bindings were tested on a pair of 178cm Wailer-112 DPS and a pair of Lotus 120’s. They have seen pretty much everything from crust to ice to soft groomers and heavy powder (December and January in the Swiss Alps). The Mantis skied very well, combining a smooth flex with no dead spots or inconsistencies with lateral and torsional control on a par with NTN. They have not been tested over big cliff drops and I only weigh in at a mighty 145 pounds. However, they were skied hard on big skis, mostly off the groomers and bounced off a lot of pillows and given a lot of abuse. Bottom line there was no shortage of control for a guy my size driving fat skis.

Skiing soft crud w/Mantis on DPS Wailers. A nice combo.

During general use the binding did not pre-release, but on two occasions (on the first powder run) the bindings did release more easily than expected. Both releases were associated with crashes when the skier went over the tips. Since these initial crashes the bindings have not released. Initially the cause was assumed to be the boot activating the release lever of the Dynafit toe piece, but after close examination it appears more likely to be a vertical release from the toe piece as the skier fell forwards while dragging the tips of the skis behind. This effect was probably compounded by heavy snow.

This behavior is not something that you’d like in a no fall zone but, while irritating to have to click back in, this mechanism would protect well against the accidental hooking of a tree root and would probably release quickly in the event of being caught in an avalanche. On balance it is not a bad thing for a backcountry binding, but is one of the factors that makes this binding a bit fiddly for everyday resort use.

Ease of Use
The Mantis is not the easiest binding to get in or out of. This is its biggest drawback – not that it impacts its intended use as a backcountry binding, but the fiddle factor is the one thing that may prevent people from choosing it for the resort.

Having a free pivot is the only way to tour and using a Dynafit toe is the best free pivot there is.

Uphill travel is superb due to the low weight and free pivot and buildup of snow was never a problem (on a day when many on NTN were suffering).

Summary

Mantis TTS – Tech toe with a large spring compression length equals no limit tele control.

Overall the Mantis delivers on its objectives: it is lightweight, has a free pivot, releases and delivers excellent skiing control. It combines the control of NTN with the smooth flex of a Hammerhead (Axl/Vice). Based on control and flex alone, the Mantis can be skied as an every day binding. Initially I concluded the fiddle factor was too much for resort skiing when compared to NTN with its “step-in” feature and brakes.

Since then I logged two weeks of touring in Canada’s Selkirks with 120mm wide skis. In that time there were no pre-releases, no breakage, and no icing issues. They toured extremely well, and the control is better (less lateral slop) than NTN Freerides. The only minor improvement that I want is to make the cable hook more positively behind the heel post so it is less likely to become unhooked when touring. At this point my preference is for TTS over NTN in-bounds or out.

What’s next?

Next gen Mantis TTS with steel reinforcement.

Since the original design presented above, the Mantis has been modified with a light metal bracket with a pin for the cable pivot. This part is designed to address concerns over possible long term delamination of the carbon fibre riser from the cable attachment and also to provide a support to the boot under the bellows.

This part works well and the Mantis is going to see a simplification of the riser design which will combine with the bracket such that it can be machined in 2 simple parts. Also on the cards are an interface to the new NTN mount patterns and a new version that dispenses with the teleheel and uses the ‘NTN second heel’, tensioned with a front lever so that it is easier to get into / out of. Prototypes of this approach show that the flex feels identical to the heelthrow version, but it will take a bit more time to design a robust, lightweight tensioning mechanism (and to save up for more prototyping).

Conclusion

Mantis TTS – homebrewed evolution of the face of telemark.

TTS is a great concept with a lot of potential for further development both in the release, mount and connection to the boot. I hope that it continues to develop as it really could deliver the ‘holy grail’ of telemark bindings.

Design Concepts
(Editor’s note: On the next page Ben examines the forces at work in a telemark tech system. This may help to mollify the analytical unbeliever on the durability and functionality of such a spartan telemark binding. Or not.)