Mountain Biking - FSR bob unacceptable

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.

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

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

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? :(

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.

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.

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 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? :(

I would guess low air pressure in the shock.

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.
I run the shock on my FSR at about 10 to 15 lbs under rider weight (including gear) So either you didn't have enough air in the shock or it's plain bad

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. When properly set the FSR system will react to bumps while remaining neutral in respect to pedaling / braking forces. The ONLY time I get any sort of "bob" is when I'm out of the saddle and this is due to my NOT having a platform shock and the fact that any sort of "spin" I supposedly have goes straight to hell. You should not have this problem

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? :(
Play with the air pressure. Start at rider weight and work down until you find a setting that allows the suspension to use all of it's travel. Remember to set sag at about 25% of total travel as well. That's why the little O ring is on the outside of the shock

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!

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

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

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

Thanks raiyn...damn saki...

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.

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

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.
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

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

Bingo.

Not enough pressure in the shock. My FSR with a much cheaper, more basic shock doesn't bob at all unless I stand up and hammer a really big gear - and how often do I do that? Plus, I have it set quite soft to help protect my back and ribs until they heal more. The stock seat however is a bit bouncy, but once I got used to it, no worries.

Guys, remember that I have a FS bike (the Trek Fuel 98) and I know exactly what is acceptable and what is not acceptable. Pedaling is not a problem (I didn't even do any out of saddle climbs) and weight is not a problem since I weigh 165lbs and drop to 155-158 through the summer. As it stands, the FSR was the problem.

Perhaps the shock needed more air, but then the person in charge seemd to adjust air for every rider's weight. Maybe he was trying to give a very plush ride. But then the Marin and Jamis were quite plush, with more travel and they managed the bob very well. Of course, they do not remain active at all times, and in fact the Jamis XLT becomes "rigid" under strong pedal forces. Result: a great climber for a trail bike and you could feel it.

Bottom line: yes I can see that with more air the FSR may have been better. But I am starting to have my doubts about a system that is active at all times. Unless you have a blow-off valve that can be tuned to your weight, I don't see how it can work. As it stands, I prefer a system that is NOT active when pedaling hard, but will react to bigger "hits" to manage climbs on rough terrain. The Fuel excells in this area and the Brain is even better.

Theres plenty of them around in Australia :eek:

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

I was over exaggerating, but there does seem to be a bit of wait over here :)

I took a friend's FSR on the trails once. I was pretty impressed, given that I have always been a hardtail fan. The suspension was really effective at keeping the rear wheel planted. On climbs where I would normally have to be very careful to pick a clean line in order to maintain traction, I could pretty much just point and shoot the FSR. It made cleaning steep rooted climbs a no brainer, as long as I had enough power to turn the cranks.

That said, the bike really wore me out. 3/4 of the way through my usual ride, I was ready to puke, and I actually had to stop for a couple of minutes to recover. Probably my hardtail riding style was not well suited to the full suspension rig, but I must say, the bike bobbed quite a lot. To me it seemed like that was a sign that the suspension was supple enough to do it's job. It wasn't distracting, just tiring.

Cool bike, but I'm not ready to commit to full suspension yet.

I've always heard that the FSR was a bob happy design, looks like a nice bike, just not something I'd want to race on. For racing your Fuel is a superior bike, or an Epic, NRS, Element, etc. I once rode behind a woman on an 04 Rocky Element50 up a fairly steep climb and was amazed at the lack of bob. Whether seated or standing I could see zero visible movement of the suspension until contact with a root.

My friend rides a Yeti Koko, which seems to strike a good balance between bob, efficiency and suspension performance without a 'platform' shock. Would imagine it would be super with one.

I'm also not ready to commit to full suspension. Once my bones start hurting, I quit XC racing, or start doing epic races I'll reconsider.

Guys, remember that I have a FS bike (the Trek Fuel 98) and I know exactly what is acceptable and what is not acceptable. Pedaling is not a problem (I didn't even do any out of saddle climbs) and weight is not a problem since I weigh 165lbs and drop to 155-158 through the summer. As it stands, the FSR was the problem.Not from what you've told us


Perhaps the shock needed more air, but then the person in charge seemd to adjust air for every rider's weight. Maybe he was trying to give a very plush ride. But then the Marin and Jamis were quite plush, with more travel and they managed the bob very well. Of course, they do not remain active at all times, and in fact the Jamis XLT becomes "rigid" under strong pedal forces. Result: a great climber for a trail bike and you could feel it.Like I said perhaps the guy set it completely wrong. Just because he sells bikes means he knows how to set up a suspension. Suspension that becomes "rigid" under pedalling forces is NOT a great climber as the wheel will not follow the terrain as smoothly as a suspension that isn't influenced by pedaling action

. As it stands, I prefer a system that is NOT active when pedaling hard, but will react to bigger "hits" to manage climbs on rough terrain. The Fuel excells in this area and the Brain is even better.My Rockhopper FSR with a plain Fox Float R handles climbs beautifully. Perhaps he didn't set the rebound dampening properly?

I was over exaggerating, but there does seem to be a bit of wait over here :)
;) Poor you guys, they are nice bikes.