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Laterally Stiff DH frame?

5K views 50 replies 33 participants last post by  Jerk_Chicken 
#1 ·
Who makes the most laterally STIFF FR/DH bike with 7" or more of travel? What design is most likely to achieve this?

VPP, FSR, Single Pivot, 4 Bar, Others?
 
#2 ·
Im going out on a limb and say FSR. I would asume that the location of the pivots would kind of triangulate the pivots minimizing side to side slop. But, I am sure someone else will say something else. I will put vpp at the bottom. Just because I have not seen a bike with vpp that didn't have a little play in it. I will also say that it depends on manufacturer. Any body remember the old design of the RockyMounain DH bike (don't remember the name). You could move the rear wheel back and fourth like an inch. It was a new bike. :eek:
 
#3 ·
Actually FSRs are traditionally one of the tougher frames to make laterally rigid. The pivot in between the rear axle and the main pivot (the FSR pivot) makes it difficult. Turner used bushings to help solve this, needle bearings are expensive and hard to design into the confined space, other companies use big bearings or even double-bearing sets.


You can't really ask this question though, a Knolly DT is a much more massive and rigid bike than a specialized FSR, although both have FSR pivots.

On the same token, a Santa Cruz heckler or other older single pivot design is a far more flexy bike than a foes. Foes uses stiffening-swing links that reinforce the rear end to prevent flex and twisting of the swingarm. Both are classified as "single pivot" due to the wheelpath being controled by one pivot.

Ibis makes a fairly flexy DW-link bike by today's standards, while Pivot Cycles makes an exceptionally rigid one.

Some of the bikes out there feel super stiff in the showroom, but what about 6 mo later or a year later? Did they design the pivots to hold up and keep the bike rigid that long?

You just can't make any overall arguments any way, you can only look at specific executions or variations. There are some general rules, such as the elevated-swingarm style single-pivot (older santa cruz) are difficult to make very rigid, FSRs require something "special" to deal with that extra pivot, any bike that uses undersized pivots will probably be flexy, any bike that uses 2-peice rockers or exceptionally long rocker/suspension parts will probably flexier than ones that do not, and so on, but these are pretty specific situations.

You can make a flexy FSR, a flexy single pivot, a flexy DW bike, there are examples of each. You can make stiff bikes in the above catagories as well. Generally the more expensive the bike, the more thought is put into things like the pivots and lateral rigidity. More $$ doesn't gaurentee anything though.
 
#4 ·
think of it this way: the more pivots between the b/bkt amd the axle or the shock stay yoke and the axle, the more flex, be it lateral or otherwise, yer likely to have. many of the stiffest dh rigs use a single solid rear tri and a upper linkage assembly. i know of 1 rig that will use a dw link and goes against this theory that show positive test data but its not there yet.

the '08 and prior turner dhr fits in this catagory. its said to track better than anything out there and be plush while remaining mostly bob free (for a long travel system) and be mostly void of brake induced negitive behaviour known as brake jack. the sunday kinda kicked its ass in suspension travel quality last year but suffered from bearing issues that killed lateral stiffness till replaced. turner still makes replacement parts and has them in stock at all times.

if yer lucky like i was, you can find a old square tubed dhr from '06 or '05 for dirt cheap. these things are built like tanks so they last and come with a no questions asked $500 trade in on a new frame. overall theyre damn hard to beat. im sure theres other options but be aware of long term history, parts availability and customer service issues.
 
#8 ·
This here is the most Laterally stiff bike i have ever felt!!!!! well a hardtail like a banshee morphin

I have ridden transition dirtbag and BR, Santa cruz nomad, bullit, and heckler, Specialized demo 8 and 9, Intense socom and SS, Nicolai ufo ST and Helius, ellsworth joker, karpiel disco, kona stinky, knolly D-T and probably a few others. out of them the Nicolai UFO pictured below was the stiffest. its adjustable 6 to 7.7 inches travel and really cool geo too. i wish i had bought a large.
 

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#9 ·
climbingbubba said:
This here is the most Laterally stiff bike i have ever felt!!!!! well a hardtail like a banshee morphin

I have ridden transition dirtbag and BR, Santa cruz nomad, bullit, and heckler, Specialized demo 8 and 9, Intense socom and SS, Nicolai ufo ST and Helius, ellsworth joker, karpiel disco, kona stinky, knolly D-T and probably a few others. out of them the Nicolai UFO pictured below was the stiffest. its adjustable 6 to 7.7 inches travel and really cool geo too. i wish i had bought a large.
You might think that, and it's probably on the stiffer side of things, but it's also limited because it's single pivot and there is no top swing-linkage reinforcing the rear triangle, as with a foes. This means your rear triangle can "twist" a bit on the off-camber hits and trails. The positive aspect is that it's pretty much a "fully triangulated" swingarm, which is a lot better than the elevated-chainstay design like an older bullit, but the next step up for that type of design is a swing-linkage that stiffens the rear triangle, even if it doesn't adjust the shock rate at all. Foes uses such an arrangement. I'm not implying that nicolais are flexy bikes or that your bike is flexy, just that there is another step above it. It also looks like you'll get quite a falling-rate towards the end of your travel.
 
#14 ·
Captain Snakebite said:
Im starting to see a pattern...Single Pivots are making a come back!
all im gonna say is K.I.S.S
Keep
It
Simple
Stupid

sure the other designs may be good for one reason or another but why fix somethin if it aint broke? single pivot is ole school and it works so why improve it ? IMO

got a prophet...and a bullit there cheap(er than most designs) and work great. sure there is some break jack but how does that differ from good old hardtails...they have the same problem right...
 
#19 ·
from what i have seen.....

the Foes SP design with the swinglink seems like the stiffest design out there. huge massive swingearm with massive pivots like many other companys out there.....but with the swinglink at the top, then the swingarm can only twist a bit, instead of moreso. but thats just me.


i think everystinglepivot needs a swinglink type steup otherwise its not designed to its full potenial. period.
 
#26 ·
I knew this was going to turn into a pissn contest.The Demo is rediculusly stiff. It is the stiffest bike I know of. Other bikes might be close but I have a hard time beliving anything else is stiffer with out the sacrifice of wieght/over enginering. Even my SXtrail is really stiff, but it doesnt come close the demo.
 
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