Did the tour on August 1st. Can only agree with the enthusiastic comments.
Thanks to the forecast thunderstorms, there were fewer hikers. At the beginning we had to take shelter for a short time at an alp due to a thunderstorm cell. The first DH to the lake leads across the pasture and also challenges us in terms of line choice to avoid surprising holes. DH from the lake is stony and partly technical. The line choice was not right and cost me a rear wheel spoke. Well, a new bike was long overdue.
We were on the road for just under 3 hours, not counting the break with a cheese slice on the Iffigalp.

Cool trail if you are not afraid to carry/push your bike. You will be rewarded with a beautiful turquoise Lake Iffig in the middle of a magnificent mountain world. The trails are partly rough, rocky, washed out and then flowy again. Another highlight is the Iffigfall waterfall. Happy trails!

We rode this tour today: The trail up to the Tungelpass was almost continuously rideable in terms of steepness. The ascent with the pushing and carrying section was strenuous, but manageable if you are sure-footed.
You are rewarded by the beautiful panorama with the turquoise-blue lake at your feet.
The descent down to the lake is a tough one. We were able to ride almost everything - but in the S3-S4 range.
After the lake, we continued in the same enduro style: go, go, go and a good choice of line helps.
The descent after the restaurant is very nice - make sure you stop at the waterfalls.

Here is a link to the video: https://www.youtube.com/watch?v=QFuv1mlgNTU

Did the tour on Saturday. Gondola running, no more snow, wonderful weather!
I would ride directly to the Tungelpass instead of taking the small detour to the Stübleni. The ascent with the bike on your shoulder is no problem if you often do tours with carrying passages. The bike on one shoulder, the other hand on the rope.
The descent to Iffigsee and Iffigenalp was also at the limit for me and not all of it was rideable. But I was aware of this when I set off on the tour.
The trail from Iffigenalp is awesome and easy to ride with lots of roots and rocks.
All in all, a very nice tour!

I did the tour today and it was really great. The Betelbergbahn is not yet in operation so it took 2.5 hours to warm up to the mountain station. But it was wonderfully lonely and easy to enjoy.

Another advantage of doing the tour rather early in the year is that there were practically no cattle gates yet and from Iffigenalp there are many mobile ones, so thanks to the municipality of Lenk!

Tip: There are still three snow fields on the trage passage, which I preferred to avoid as I didn't have poles. Actually no problem but with poles it would be better and easier...

Beautiful and very varied tour. Can only agree with the other comments: A highlight in the Bernese Oberland.

The climbing section requires full concentration for a short time, but can be mastered easily with good surefootedness. Typical for an Oberland tour, the bike has to be lifted about 15 times over a hiker's turnstile. From the Iffigenalp, however, that's the end of it and unbridled riding fun follows along the Iffigbach to Lenk.

We started the tour directly from Lenk with an ascent via Lenk Wallegg - Rütiweid - Leierliweg. The trail is easy to ride, but so steep in places that the bike has to be pushed.

Very cool tour for good riding technicians and lovers of crisp enduro trails. Almost everything was rideable for us, even if it was really difficult in places. One thing that definitely has to be mentioned is the ascent from Tungelpass! Carrying the bike is almost standard for us, but the key section with the ropes and chains in the rock was borderline and required surefootedness, strength and some climbing skills ;-)

I can only agree with g.ginggen_34404. It's certainly one of the best "natural" enduro tours I know of in the BEO. Great trail!

Rode on 18.09.2019. What a great tour! Conditions were great, dry as dust. Significantly more difficult in wet conditions. The ascent briefly requires good surefootedness, otherwise no dangerous sections. The bike has to be carried up for about 30 minutes. A good choice of line is necessary on the descent. After Iffigensee there are many loose stones in the way, but they do not pose any major difficulties. From Restaurant Iffigenalp, the trail fun is unfortunately spoiled by countless turnstiles. All in all, you have to be aware that there are always sections of pushing on this tour. Such a great tour and in the Bernese Oberland, Lenk think!

I really liked the part after the Iffigenalp restaurant. It's a narrow trail but 95% of it is easy to ride and the last 5% could have been managed with a bit of effort.

But I didn't like the part before that. The ascent with 300 meters of altitude was hard at the limit. Bike on the back and hand on the safety cable was almost a bit too much.

Even when we reached the top, the only good thing was the panorama. The trail was very difficult to ride. There were always places that just didn't work.

Further down after the lake was the worst part of the day. A 100-meter section that you have to run down completely because it would be too dangerous if you fell over.

After this point, our power, motivation and confidence in this trail suggestion had almost disappeared.

The Iffigenalp restaurant was then able to boost our motivation again and the descent along the Iffigen Falls was magnificent. This route would actually have been enough for us.

But we pushed through and it was a good thing we did. Not that we had much choice after the ascent.