TanTan FM10 29 Rear Suspension

[Rockyupgrade]

I have ordered the FM10.
I am still confused about best rear shock size.
The bike seems to want to mimic the suspension set up in the Rocky Mountain Instinct.
https://www.bikes.com/en/bikes/instinct/2019
I have and love this bike so am trying to mimic it in the setup.
I got a 140 mm front fork.
And ordered a cheap DNM 190mm by 50 mm shock.
https://www.dnmshock.com/products.php?func=p_detail&p_id=20&pc_parent=13
If it sets up well I will upgrade.
The question is around the trunnion mount.  I see lots of talk on the site about trunnion but don't see it listed as an option anywhere.  Can anyone confirm if the newest version requires trunnion.
I was sent a spec diagram so have included it for others.

[emu26]

Yes it is trunnion.

FWIW my opinion is that a 140mm fork is going to be too short unless you intend running 165mm or 170mm cranks.   I know that the website says 135 - 150 but I really think the bb is too low for the lower end of the travel range.  As I said, just my opinion, others may disagree.

[Rockyupgrade]

Thanks...  I will look for a trunnion mount suspension.
I appreciate your comment on the 140 mm fork.  I will keep everyone in the loop

[binaryagent]

Yes it is trunnion.

FWIW my opinion is that a 140mm fork is going to be too short unless you intend running 165mm or 170mm cranks.   I know that the website says 135 - 150 but I really think the bb is too low for the lower end of the travel range.  As I said, just my opinion, others may disagree.

A larger travel fork will also decrease the head tube angle. I already feel like I'm driving a chopper bike sometimes. I have a 185x50mm shock and a 140mm fork and I was getting a fair amount of pedal strikes with large Stamp2 pedals on a large frame and 190 lbs bodyweight. Eggbeaters have helped but I've been thinking about raising the rear end for a while. The flip chip holes are about 11mm apart but at an angle so probably around 9mm difference. A 200x57mm shock should add around 6mm to the total length of the shock and therefore raise the rear end a bit in addition to adding 15mm of travel.

I'm not certain about my calculations though because I see in the included attachment a length of 205mm for the longer flip chip setting. This image is from the AutoDesk drawing on the TanTan FM10 product web page: http://www.tantancycling.com/index.php?_m=mod_product&_a=view&p_id=862

Anyone have more info about whether going from a 185x50mm to a 200x57mm shock will raise the rear end?

[binaryagent]

I just took some measurements. At full extension of the suspension the pivot arm hits the downtube at the following measurements:

Short flip chip: 193.7mm
Long flip chip: 201.6mm

So a 200mm shock in the long position will make the bike sit a bit higher than a 190mm shock in the short position.

[Rockyupgrade]

I ended up running a 150 mm front fork and a 200 x 53 DNM rear shock.  Seems fine, until I noticed the rear shock seems to be hitting the rear triangle...  I noticed a similar problem from others.  Does anyone know if they have arrived at a solution for this?
Thanks

[emu26]

How does the rear shock hit the rear triangle?

[Rockyupgrade]

When it fully compressed the nose touches the pivot.

[emu26]

Have you tried the flip chip in the other position?

[Rockyupgrade]

I haven’t because they state the chip has a length of 185 mm in forward position.
If accurate it would reduce suspension by 15 mm and travel correspondingly.

[SVChucko]

I got a medium FM10 frame and put a 185mm Manitou Mara shock on it. There's about 10mm of clearance between the seatstay yoke and the seat tube at full extension. They claim 150mm of rear wheel travel with a 185x55mm shock, but I'm skeptical. (I also don't know a good way to measure rear suspension travel.)

[emu26]

I got a medium FM10 frame and put a 185mm Manitou Mara shock on it. There's about 10mm of clearance between the seatstay yoke and the seat tube at full extension. They claim 150mm of rear wheel travel with a 185x55mm shock, but I'm skeptical. (I also don't know a good way to measure rear suspension travel.)

Secure your bike in a bike work stand so that both wheels are touching the ground.  Measure from the ground to the centre of the rear axle. Drop all of the air out of your rear shock. Without moving the bike in the stand (it is important that the BB height and front end remains static) lift your rear wheel up of the ground until you have used all of the stroke on the shock. Measure from the ground to the centre of the rear axle (you might want a helper for this)  subtract the first dimension from the second and that should tell you how much rear wheel travel you have.

[Jotegr]

This won't account for a curve in an axle path but it's a good approximation. Should reveal big discrepancies like 135mm vs 150mm or something like that.