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Discussion Starter · #1 ·
Hello all, I own a Fantom Team with the Monarch 4.2 and have the following question, Would the geometry change when setting the shock in the 5 in.hole (closest to the downtube) as when the shock is in the 4 in. hole? I changed it to the 5 in. setting and had to inflate the shock to about 265 (I weight around 175 lb / 79 kg) and went out for a ride, and it was impossible to climb in the very steep climbs that I go up in the 4 in.setting. I struggle to climb in the 4 in. but in the 5 in. it was just not possible even seating in the front of the saddle and putting my chest near the handlebar...travel setting should be adjustable on the fly...I measured the bb height through the 3 settings and couldn´t find a difference (with measuring tape, not that exact)
 

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Why was impossible ? The geometry does not change appreciably . The shock shaft speed does change as well as the leverage ratio . The 5 " position would require higher shock pressure because of the increased leverage , it would also increase the shaft speed . The increased shaft speed could require more damping to prevent "blowing through the middle".
 

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When I first attempted to adjust the travel on a Fantom frame I thought the geometry would change also. but just as you observed I found very little (maybe no) change in the BB height. However I feel that the leverage ratio in the 5" travel setting gives way to much pedal bob, even when increasing the psi on the shock. I suspect it was harder to climb because the suspension was soaking up more of your pedaling force, or the rear just sags more going up hill in the 5" setting making the front end lighter.
 

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Discussion Starter · #6 ·
hello, I have raised the pressure in the rear shock to about 260 and now the problem is solved, back to the same feeling as when the bike is in the 4 inch setting...must have been the sag as you say...would setting the waste gate to the + or - would stop the bobbing? or is the gate not related at all with this?
 

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I also had to run big pressures to get the appropriate sag, but that still can't compensate for the large leverage ratio resulting in very little shock travel per suspension travel. This is a key to shock dampening performance as it is reliant on the amount of oil being forced through orifices in the shock. The excessive "bobbing" is a direct result of this, imho.

The only way I could reduce the bobbing was by locking out the Monarch 3.3 on my DS Pro, which resulted in too harsh a ride for me. On your Monarch 4.2 you may be able to find a better compromise with the fine gate adjustment.

Really hope Motobecane/BikesDirect/Mike redesigns the Fantom to use a 2" stroke shock for their future 5" offerings. Seems to me it'd be trivial to move the lower shock mount down the seat tube or onto the down tube for more shock stroke. If I had more welding skills I'd be tempted to do this myself :)
 
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