This weekend I demoed a Specialized FSR Comp 120. It is a beautiful bike, with great geometry and I wanted to experience the "always active" rear suspension that Specialized keeps advertising.

What a huge disappointment! The bike bobbed like crazy, more than any other FS bike I have ever tried out - and I demoed lots of them in the past 2 years.

So let's rationalize this: if the bike is built to remain active under pedaling and breaking, then the only thing that is going to save you from bob is a shock built with a ProPedal (or similar) setup. Well the bike comes with a Fox ProPedal Septune shock (it has seven settings hence its name) and even in the stiffest setting the bob was ridiculous. Either the blow-off valve was not working or the bike just sucks. I cannot believe this bike sucks, so I have to conclude that the shock was faulty. There were others who noted this and we told the Specialized person that bob was a serious problem. He indicated that it is OK and he even races with this bike. Well that took away some credibility, since NOBODY would race on such a setup.

I tried other trail bikes (Jamis XLT, Marin Mount Vision) that were superior to the Specialized in managing bob. And these are 4-6 in travel bikes! So what gives? :(

Raiyn must be out riding or working. He will definately have some advice for you on this subject.

I always found the term active suspension under pedalling and interesting idea. That means it bobs. I also love when people say "pedals like a ht"...no, no it doesn't. It bobs. Thats not like a ht. FSR is good but it bobs, its suspension. If you want NO bob at all, get lockout. Every suspension I have tried bobs if you want active. Trek fuel, doesnt bob much at all, it shock and suspension are deisgned to be stiff, but guess what, it isn't active.

Its simple, and I love fsr, but you fell for the marketing. And you didn't have a completely honest salesman. FSR manages bob better than those other bikes while maintaining active suspension. The last part is the key. Some newer designs are beginning to prove better but they still bob while maintaining active suspension. I rode an enduro around and loved it...still bobbed. I learned to use the bob to my advantage, since my trails are really technical, having a little negative travel is a beautiful thing. But, I would hate it if my trails weren't tech :)

Also, and this is key, you will have to relearn to pedal. On my bighit (it bobs lots) I have to have perfect pedalling, any piston type pedalling and thing pogo's. Its a learned thing, especially if you come from a ht.

My simple take, from a non xc guy, you will never get that perfect bike. If its active, it bobs, if it isn't active it won't bob. You have to find YOUR perfect balance. Means a lot of testing and reading. Dw link and vpp offer a whole new feel to this idea, would be interesting to try, the reviews are amazing to date. That and Dw is a great engineer and truly a geek.

The brain (specialized) is likely the best bet as the shock doesn't bob when the shock is pushed down but it activates when the shock is actuated up (from the ground) however its weakness is in how quickly the lock valve opens up. So again, if that is a balance you like, then it would work.

Thats my take. Truly Active suspension without bob...an impossible dream.

Wow...thanks for your contribution! :)

I'm no engineer, but I don't know that I'd say bob will NEVER be eliminated. I noticed that most ds models (any I've ridden at all) this year have made improvements in terms of the amount of bob, and some are getting quite good. The brain sounds like a mechanism that I had previously thought would work, I just didn't know how the hell that would all be put together. I have not yet seen one of these, but sure would like to get my hands on it for a while.

-RotD

http://www.specialized.com/bc/techlab_brain.jsp?a=b

There is some more on the brain.

I am no engineer, I just think what I think of active suspension (negative and positive travel that actuates on small and large bumps) will be impossible to eliminate while offering NO bob. Obviously a balance is possible for anyone. Maybe I will be proven wrong, but the closest thing so far has been the brain, and I didn't like how it felt on small bumps. :)

I have a 5th air and it still bobs at times it all depends on how you set the air pressure. A friend of mine has the bike you tried( he owns a bike shop that has specialized)and he wants to put a 5th air on it.I wont kill all the bob but it helps a lot.

Serious, If you dont mind me asking, how much do you wiegh? I test rode a stinky on the weekend and even with 7 inches I noticed no bob unless I actually stood up and tried to bounce. But the catch here is im only wiegh in at about 120. I gues for stuff like this when It comes to "bob" im lucky!

i have the aline and it has 9inches of travel and as long as i dont stand up there is VERY little bob.

the only way to experience no bob is with a HT

I have the same bike and I've experienced the same problem. Following Specialized air pressure recommendations lead to a ride where the rear end compresses most of the way into the travel when ever I would take off from a stop. Not a great feeling. The Fox website suggested much more air in the shock than the Specialized for my weight (230 lb :mad:). I ended up putting about 240 psi in the rear shock which has lessened the bob. Check your sag to determine the pressure you need. I found that if I was at the 3/4" of sag suggested, that the ride is better.

If it is THAT unacceptible, get yourself a hardtail. Less money, and no bob.

Your statement is true for single pivot bikes. However, the term 'bob' is relative...all suspension systems will compress and rebound when either 1) the terrain varies or 2) you increase the force on them by shifting your weight as you pedal. What makes the FSR design stand out is the fact that pedaling forces (on the chain) do not act on the suspension as with other designs.


I would guess low air pressure in the shock.

Simple reason, you are a rare case, but the spring is actually UNDERSPRUNG. That bike should still bob a bit. :)

oops...yeah oversprung. At 120 you need a lighter spring

Thanks raiyn...damn saki...

Saki's some good **** Nothing like rice wine to make you numb :D

Numb ain't the word. Was a good night, first time in a few months my gf and I had some time to ourselves.

Ahh 'nuff said
http://img210.echo.cx/img210/3839/farttenting1jf.gif

The best bike I have ever tried in the no bob department (not including HT's ;)) was a GT DHi Drive, it has 9inches of travel aand it pedaled so damn close to a HT that it was amazing. The DW link is also really good, I tried my mate's Sunday and it pedalled pretty good. Also if the Yeti 303 lives up to the hype it will be brilliant.

I found on my old Bighit Comp, it bobbed but the FSR was a nice system, it is impossible to make a dual suspension system that will have absolutely no bob, remain pefeectly active under braking and pedalling and not give feedback through the chainline. If there were a way, that bike company would be RICH!

Mates sunday....they haven't been really released yet and the waiting list is about 10 months long...whats your mates name haha :)...gotta be a pro.

Ill be sure to let you guys know what the 303 is like. My friend gets one in around a month or so :D

Theres plenty of them around in Australia :eek:

And just as a side note, Hardtails bob :D If you want no-bob, go rigid.

In Aus if you go to a national round every 5th bike will be a Sunday. At interschools (only school kids race) there were about 15 and there were about 140 competitors. The Sunday is a nice bike, but one of my friends who has one has had bearing problems and the other one just gave himself 30+ stitches from a stack through a rock garden on someone elses M3 because his own Sunday had a hub destroy itself.

I have plenty of friends with nice bikes :p

:beer:

Bingo.