Thanks for sharing this report. I was recently considering the Tantan FM122 myself, and after looking into it more, I'm starting to have serious doubts about the frame. Your experience definitely adds to those concerns.

Really appreciate you taking the time to document the issue. Reports like this are very useful for people who are considering buying the FM122.


certainly more useful information than prattle about lightweight aluminum trail bikes, which Frederic is building 

What made you conclude that I've made up my choose? Did I say I was going to buy a Chisel or a trail frame instead and build a lighter, better, and cheaper XC "weight weenie" bike out of it? Actually, I expect you to demonstrate it to me.

It is primarily geometry that determines the intended use, not weight. Especially when we're talking about negligible grams.

How much difference does 400 g of frame weight actually make for an XC racer? I would also argue that 400g of extra weight in the frame is less significant than 400g added to the wheels/tyres, where rotational mass has a more noticeable effect on acceleration. So, you're concerned about weight, yet suddenly you're willing to opt for a trail bike—instead of an XC bike—with a heavier trail fork and heavier trail wheels and tires?

So unless you're chasing every last gram for a pure race build, I wouldn't consider a 400 g difference in frame weight a particularly important factor by itself.

In my opinion, probably much less than people tend to think. If you compare, for example, a 10.5 kg bike with a 10.9 kg bike, the difference is only about 0.4% of the total system weight once you include the rider.

Why do you start with weight if you then switch to reliability? Alu is subject to material fatigue and is essentially non-repairable. Knowing that, I would never buy an aluminum full-suspension bike.

I am aware of the FM121 issue—in fact, I started this thread with that very knowledge, if you had read carefully.

I would never buy a frame, wheels, or handlebars from AliExpress. There's no such thing as a verifiable origin on AliExpress; you have no real certainty about what you're actually buying. But Tantan is a bit of a different story. I even know a local brand that uses some of their frames, and they aren't bad at all. The problem is that horror stories spread much more easily than good ones.

My friend, 2,720g of aluminum for $2,000 is a waste of money more than anything else. Weight is just one of the added benefits of a carbon frame. However, in terms of weight, even entry-level carbon frames from leading manufacturers don't differ much from aluminum ones. Or do you want to compare a $600 frame with an S-Works?

It's not that much relative to body weight.

I just came across the new Tantan FM122 frame, which seems to be an updated version of the FM121.

At first glance, it looks like they have redesigned the rocker link and kinematics. The top tube and the shock mounting area also appear to have been revised compared to the FM121.

The frame is listed as a 29er, Boost, UDH-compatible XC frame, using a 190 × 45 mm rear shock.

So far, it looks like only size M is available, but it could be interesting to see whether larger sizes will be released later.

Here is the link:
https://www.seraphbikes.com/chameleon-White-Seraph-Logo-29er-Boost-Suspension-Carbon-Mountain-Bike-Frame-FM122-UDH-Hanger-XC-Frame-Compatible-190x45mm-Rear-Shock-p7202729.html

One thing worth mentioning is that the FM121 was removed from the product lineup some time ago. I also came across reports of failures on some FM121 frames around the top-tube area. As far as I understand, there was some speculation that this could have been related to the frame design, construction, or possibly the suspension kinematics.

I don't know whether those reports were ever officially confirmed or what exactly caused the failures, so I don't want to jump to conclusions. However, considering how much the rocker, kinematics, top tube and shock mounting area appear to have been changed on the FM122, I wonder if these changes could be related to the issues with the previous FM121.

I'd be interested to hear if anyone has more information about the FM121 issues or knows what exactly has been changed in the FM122.

The frame itself looks like an iteration of the Edge Red Deer, aka Fina Trail Scout.
https://www.edge-design.com.tw/Spec-RED%20DEER.html
https://www.finnacycles.com/en/trail-scout/422-finna-trail-scout-frameset.html

Here are a few frames with older geometry and short travel also in XL size
https://www.trifoxbike.com/mfm100-full-suspension-carbon-mtb-frame
https://www.workswellbikes.com/prdocuts_detail/18.html
https://www.seraphbikes.com/29er-Boost-Carbon-Fiber-T1000-Disc-XC-MTB-Frame-FM198-Travel-120mm-Black-Matte-Max-Tire-29X24-p4779778.html

I found this frame from a local dealer. But it has a different rocker. The shock connection is on single pivot with the rocker and rear triangle. Size of the shock is then longer, maybe 190mm.

Another brand using this frame:
https://audaxbike.com/bike/191/fs-900-axs

Design and geometry are similar to the superior team xf 29 . Im quite impressed with this frame, looks good. Thinking about him.

Quote from: Nenokkias(fin) on October 27, 2020, 02:47:24 AM
I build one..  10.3kg .

I have this frame mfm100 and I want to ask if additional mounting of the spacer between the main pivot bearings is needed? I have feeling that the clearance is in the longitudinal plane of the rear structure.