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Is it possible to convert an HD to 150mm?

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neblackb

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Discussion starter · #1 ·
Hey guys. I am wondering if it is possible to make the HD in a 150mm travel in the rear? I want an HD an know that I would use a TALAS 150 fork, and just think it would be cool to have 150 rear travel rather than 140 or 160. Can I use 160 limbo chips and just go to a 7.875x2.25 shock? What would that do? I just don't know enough about the suspension stuff to be sure what would happen going with a set-up than what Ibis has listed. Any feed back is great. I am just thinking crazy here, or is it possible? Or should I just do the 150 fork with 160 or 140 rear? Please help.;)
 
#2 ·
neblackb said:
Hey guys. I am wondering if it is possible to make the HD in a 150mm travel in the rear? I want an HD an know that I would use a TALAS 150 fork, and just think it would be cool to have 150 rear travel rather than 140 or 160. Can I use 160 limbo chips and just go to a 7.875x2.25 shock? What would that do? I just don't know enough about the suspension stuff to be sure what would happen going with a set-up than what Ibis has listed. Any feed back is great. I am just thinking crazy here, or is it possible? Or should I just do the 150 fork with 160 or 140 rear? Please help.;)
Click to expand...
I'm going to try it, but it will be a while before I can.

My PUSH tuned coil Vanilla RC stroke was shortened by PUSH with a permanent spacer form 2.25 to 2.0 inches to use on my trusty old Mojo C. Now mounting the same shock on the HD, it appears the wheel clearance at bottom travel MIGHT still clear with 2.25 inch stroke using the 140mm travel mounting chips.

I'm afraid to cut the machine-fit spacer off, and risk damaging the shaft, so I'm planning on getting the coil serviced again soon by PUSH and they can remove the spacer while it's apart. If the tire doesn't clear the seat tube, it's easy to hand make split-washer like spacer shims for the shock shaft, or buy split plastic washers from the hardware store, to limit bottom travel, for coil or air.
 
#5 ·
The point in the exercise for me, would be to find the optimal rear travel for the HD running 650B front and rear. Try a WB Loop 650B 150mm fork, then experiment with the rear travel to find the best balance. Maybe make your own Limbo chip, use different travel shocks to achieve correct ride height and full travel without bottoming out. Ibis, how about a factory 650B option? I currently have a Mojo SL 650B F/R and may never ride 26" wheels again and am not a fan of 29r's, but they're getting better for FS.
Starting to plan my winter project now.
 
#6 ·
When I asked this question a while back, Hans posted on here saying that the rear tire would end up hitting the seat tube. That's with a 26" tire. I have everything I need to test it out except time. 140mm links & 7.875x1.25" RP23. It would be nice to find a set of shock spacers so I don't have to pull them off the 160mm travel shock.

Just remember that you better push down ridiculously hard with the shock empty to really find bottom out position and know it won't hit. It would suck to find out on the trail.

Sorry, but I really don't get the 650B love here on the Ibis pages. With the acceptance of 700C, it just seems like an extra standard that doesn't have the legs to really grow much farther. For me, 26" wheels work just fine 90% of the time, and the 29" wheel seems a tad better the last 10%. I used to do DH with a 24" rear and when I switched to 26" it wasn't the revolutionary improvement everyone said it would be. Oh well, carry on.
 
Discussion starter · #7 ·
Well I think Hans would know. I decided to go with the HD 140 and ordered today. I think I should be ok with the 150 TALAS in the front and 140 in the rear. That is what I was running on my LTc. I cannot wait to get it built. That for everyones input on this.
 
#8 ·
It seems like the 200mm shock mated to the 160 limbo chips would likely require some shimming to avoid seat tube contact. The 140 chips space the upper shock mount a little further rearward, if I understand correctly, so your wheel is starting out in close to the same spot as in 160 mode, but stopping short and leaving extra wheel clearance at bottom out vs what you get in 160 mode. Using the shorter shock with the shorter 160 chips should move everything into the deeper end of the wheel travel range....probably too deep with a 650b wheel to avoid seat tube contact...... hmmm....
Can't wait to hear what you guys find....hopefully somebody will try it soon... might be another viable setup option which, if done correctly, would drop your bb height, slacken everything a bit, and still provide a decent amount of travel without (hopefully) bottom out issues.

Side note... I'm loving the full 650b on my SL. The isses to get around: tire clearance, bottom out, and ride height are pretty well documented already. Can't do anything about tire clearance, and bottom out is easily tuned out with shimming. For ride height and overall shock rate, I've found a really nice balance by installing Fox's medium volume reducer in my RP23, and then dropping a surprising amount of air pressure. I used to run 165psi, which resulted in about 20% sag max (maybe a little less) in order to avoid frequent bottoming. Now I've got 130mm of available travel after shimming, with 30% sag at 140psi, and a spring rate that provides much better mid and late stroke support. With the shorter travel and extra sag it does feel like a shorter travel bike, but not in a bad way because the spring rate is more progressive and just works better overall vs the stock very light tune RP23 I have.... a little extra comp damping would be the finishing touch I think. Anyway, sorry for the hijack.... I guess my point is that dialing the ride height and shock characteristics are key, and we have the tools readily available to do it.... so the short shock / short chip idea might be another really cool mod to dial in just what you're looking for.....but DON'T neglect to check your bottom out clearance carefully!
 
#9 ·
It would be interesting to see if someone at Ibis could get on their CAD program and do a "hypothetical" study to determine the correct Limbo Chip size, shock size and stroke for the HD frame to accomodate 650bwheels. 650b specific fork, wheel and tire are all there now, no renegade stuff.
After reading the 30 year history of Ibis and seeing that they experimented with different wheel sizes before, it would be a natural to push the envelope again!
 
#10 ·
Yeah, you're right.... all the pieces are pretty much in place.... and there may be enough bottom-out clearance wiggle room in the HD design that all Ibis would have to do is make another set of limbo chips to optimize ride height while still maintaining enough bottom clearance.
 
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