[Juhnu]

I've got a ~8" travel bike and I've had some problems with front derailleur clearance. My setup is 73mm BB, 135mm rear, double ring + bash in front.

The fd (XTR FD-M960) is installed as high as possible on the seat tube, just before the rear triangle hits it at the closest part of travel. My problem is that in this position the fd hits the bottom link of the rear suspension when in the small chainring. This hit occurs when there is ~9mm stroke left on DHX 5.0. I know that full stroke/bottom out is impossible (bottom out bumper can't reduce to 0mm) but I'm worried that in a hard bottom out done in small chainring it could be few mm's less than the 9mm above. This would lead to fd/frame damage. The only way to solve this is to space out the cranks 8mm and this would throw the chainline quite off (and stress the Saint BB cup).

Now to my question... I have emailed with the manufacturer and they have said that many long travel bikes experience this problem (fd collision in small chainring). What is Your experience, is this a common problem with 4-bar/linkage/vpp bikes? With single pivot there's obviously no bottom part to hit...

 

[w00dy]

My personal opinion is that you should toss the granny gear and put a guide on. With an 11-34 in the back I find no need for two gears up front.

That said, most bikes with that much travel werent designed with a front derailleur in mind, and it wouldn't surprise me if that were common. If your setup works, just run it. The worst case scenario is you bend your front der. and have to bend it back.

 

[keen]

Some pictures would be helpfull for aiding you w/ the problem. I have a VP Free running two rings up front w/ a E13 DRS. The Free has an angled seat post & VPP which really screw the f. der. up . I was able to grind a little off the rear corner of the cage the add swingarm clearance.

 

[GotMyGED]

Some pictures would be helpfull for aiding you w/ the problem. I have a VP Free running two rings up front w/ a E13 DRS. The Free has an angled seat post & VPP which really screw the f. der. up . I was able to grind a little off the rear corner of the cage the add swingarm clearance.

I built a VP free not to long ago. Had all kinds of troube with the front D. Tried all different designs, even "e-type" clamp. Finally just switched it to a single ring up front.

 

[keen]

I built a VP free not to long ago. Had all kinds of troube with the front D. Tried all different designs, even "e-type" clamp. Finally just switched it to a single ring up front.

I am running 22/32 rings w/ the 36t capaciity DRS. SC now recomends the Saint F. der. I modified my XT F. der. and shifting is pretty good. A lot of f. der. issues boil down too tiny adjustments here and there.

 

[Juhnu]

Some pictures would be helpfull for aiding you w/ the problem. I have a VP Free running two rings up front w/ a E13 DRS. The Free has an angled seat post & VPP which really screw the f. der. up . I was able to grind a little off the rear corner of the cage the add swingarm clearance.

I've got the VP's cousin from the other VPP company... I managed to get the XTR fd to work by adding extra spacer to the BB (in addition to E13 DRS) and some fancy Dremel work on the fd. Now I need some ride time to determine if I've succeeded. The chainline is a bit off from optimal, and there is still some situations where some contact happens, but this is in the extreme bottom out where I should not find myself in

If only the frame was few millimeters different in couple locations, then the manufacturer's suggested fd would work out of the box without modifications. Good thing I just got three seasons of American Chopper on DVD and after watching those the obvious solution was to remove metal for clearance

I wonder if this problem occurs on different suspension designs, as the VPP is quite constricted with space between the linkages.