You are hereForums / By Discipline / Mountain (off road) / MTB Gear / All rear suspension designs are created equal... discuss
All rear suspension designs are created equal... discuss
NB: Originally posted elsewhere on the Global Riders Network and appears via syndication.
I recently came across this summary of suspension designs which suggests that all rear suspension designs have their pluses and minuses:
http://www.bikeradar.com/gear/article/buyers-gui...
Do peeps agree?
- Login to post comments
- Bookmark & share
Tags
Interesting,, I believe there is a real science to it all and engineers are always working to improve their designs (within the limits of copyrights on some if not all the designs these days, Specialized licence their design to a heap of companies). I believe towards the end of the article is the real deal,
“ And we have to remember the second part of the equation –– the rider. Personal preference really is the key when it comes down to what works best for you. “
Which is a typical editorial ending (opened). I can only speak from what I’ve ridden and owned over the years, and yes there is a difference in suspension response and also a remarkable difference on what a different type of shock can give on the same suspension setup, or different tuning for that mater. Like it or not, nearly all riders, retailers, experts etc. will be biassed towards what they are riding / selling. I’m guilty of it, my new dually has the best setup ever, it rips. It also comes down to rider ability, fitness and experience, I’ve ridden with guys and girls that can ride the frekin wheels of a $300 department store bike.
In my opinion one of they key things the author doesn't mention is that one of the most important considerations for pedal bob is where the line of action of the chain tension passes through the pivot point.
All they say us the lower the pivot point the less bob. This is incorrect and single pivots have been refined so the pivot point is now generally in line with line of action of the chain tension. Typically placed near where the chain meets the front mech. This means the chain tension pulls through the pivot and causes minimal moment minimizing pedal bob. When the pivot is lower as in some old designs and down near the bottom bracket the chain tension pulls the bike down into its travel.
Pivot points higher than the chain work in reverse and semi stiffnen the back end while pedaling and pull the wheel down into the ground. Place it too high and this turns into noticeable pedal bob.
Note for four bar links such as spec, giant dwg etc that despite where the links pivot the pivot point is elsewhere in a virtual location.
Overall I agree, evolution has weeded out the bad ones and its now rider preference and what you get used to. What is your preference on the tradeoffs of leverage ratio through the travel, wheel path, bob, brake jack, budget, weight, strength, maintenance...
Can many of us tell the difference after a few rides to get used to a new bike?
The comparison is also always changing.
My '12 Demo 8 pedals way better than my '07 Demo.
The '12 Demo pedals way better than my '06 Enduro and weighs about the same. Just tweaks of the same design, especially leverage ratio and how this changes through the travel. I'll admit the Cane Creek shock helps but have also ridden the same frame with Fox and still a vast improvement.
Back ends of bikes are something I take a look all the time and spark the interest of my undergraduate learning in mechanical engineering.
The four bar link was text book stuff. New single pivots and trek etc are redefining the problem and solving it other ways and also combining the approaches.
Trek for example has single pivot wheel path, four bar type control over leverage ratio and four bar brake set up. Others are turning single pivot arguable application specific disadvantage to a possible advantage by refinement.
The Demo 8 is also hybrid and uses a single pivot approach to leverage ratio by using a shock stay while the wheel path and brakes are four bar. Note wheel path includes how much the suspension motion also rotates the wheel (and brakes).
Confused? Ride before you buy!
OI've ridden mostly single pivots, either pure single pivot or what they call faux bar. Biggest single factor is shock tune. Nevertheless I found they both pedalled best with least bob in gramny ring as this put the pivot point abive the chainring.
Rode a real 4 bar for a few months (Ellsworth) and it was better but only by a little. Mostly accounted for by 30mm less travel than my single pivot i think but the shock tune felt good.
I've noticed Hans' SC Tallboy has very little bob. Keen to try one in my size with SPDs, curious to see if pedal kickback is an issue with this design which uses so much chain growth to stop bob.
The biggest thing I've noticed is pedalling technique. A lot of people mash the pedals and no suspension design will stop this sort of bob.
With good to correct pedalling techinique, single pivots are IMO much better.
Ridden quite a few different types, and the ones that suited my riding were;
Best handling over rough terrain whilst pedalling was the Marin 5.7. It has a proper 4 double wishbone style setup. Pedalled reasonably well up hill, but it's forte was its ability to absorb rough terrain whilst being seated and pedalling. It stayed active constantly, even under braking.
Best uphill climber is the Orbea Occam, it's efficiency in pedalling is amazing and acceleration and power to the ground is surprising. It's single pivot and concentric rear pivot works really well. This has only just been awarded by me, the old favourite was the Cannondale rush. I'd like to try an Orbea Oiz or Cannondale Scalpel. These are meant to be pretty gun!
Pointing the bikes down and the multi pivot systems work a lot better both in short travel and long travel.
as for a system that can do it all, you can't go past a single pivot IMO.
Occam 29er is on my shortlist for later this year (hopefully)
I caved and ordered one LOL I was meant to be keeping the money aside for my new bub, but it got the better of me and ordered the S30X. Which one were you looking at?
That one. You're buying me a Large?
LOL!
I'm going to run the forks as is, but might lower them to 100, if it feels a bit slack. But I don't think it will for me, as I ran 120mm on my rush and loved it.
LOL!
I'm going to run the forks as is, but might lower them to 100, if it feels a bit slack. But I don't think it will for me, as I ran 120mm on my rush and loved it.
Add to the basic suspension design all of the advances in shock tech plus the materials used & pivots plus set up & it all becomes a blur of pressure, angles, pivots, stiffness, linear vs progressive and rear wheel path of travel......etc etc.
The same basic design can give a hell of a different ride!
I've ridden great & bad single pivots plus some dead feeling (Early Brain shocked) Horst designs as well as i drive & DW link. Almost all shone in some way but to me the linkage designs felt nicest overall.
I'm not a great fan of platform shocks so the 4 bar Horst link (On a Specialized) & DW link (On a Santa Cruz) are my current favourite performing suspension systems as far as out & out rear end performance goes but for XC race, simplicity & light weight there are some single pivot designs out there that with the right shock work bloody well.
Btw. How much would a rear end revamp inc shock cost on a Tallboy for example? I bet a fair bit more than a Superlight and after a year or so when those components start to wear that good performance will drop off.
E,G My Yeti ASR recent outlay as the rear was suffering stiction & the forks knocked: full rear end bearing kit $200, fork service $125, rear shock $130
Plush again, but add to the above the new hub bearings & I realise that even with some diy skill these bikes cost a bit of money to keep going sweet.
Riding this weekend, yay!
I really liked the 120/100 front/back setup on the Ellsworth. Also interested to try the short stem/long front triangle setup. Simon tells me it makes descending a lot better.
Great info. Thanks to all who have contributed. I have learnt a lot.
Seems like shock tuning seems to be important to making any design work. How do you go about doing that?
More than likely you’ll need a shock pump. the below link isn’t a bad one to go by. Main thing I find is getting the sag dialled in correctly.
http://www.bikeradar.com/gear/article/workshop-s...
If all else fails go to your LBS and they will be able to set it for and the rest of the geometry to suit as well.
I thought the shock tuning referred to above might be something more involved like changing the shock, or getting the existing shock pushed or something.
As for air pressures and sag, yep.
Push Industries has a good rep. Apparently they have local representation now. Yes, you do need to get sag right but that's not all there is to it.
There has been a fairly big advancement over the last few years finessing shock tune. Big difference between my Jekyll and Rize, for example is quite noticeable, and it would have advanced even more since. The new CTD setup from Fox sounds really interesting. Combined with a handlebar remote, sounds like the best of all worlds. Of course, a well-set-up Brain shock would do all that without you having to think about it.
I'm constantly amazed at the set up of some people's bike shocks whether shop set or user set.
My non tech friends Giant Anthem returned from its first service (lge local chain store)with no rebound damping at all & enough pressure in the fork for a 20kg heavier rider plus 50psi in both tyres & a girl friend of mine was setting her fork rebound to fully open in the belief that you hopped the front end over obstacles by bouncing the fork like a pogo stick,!
For most, the rear shock is generally less user tunable so is more straightforward to set up but a dual air or RLC type fork up front may need a bit of understanding/experience to get the most out of it & balance it with the rear. User preference & type of riding also comes into this.
What bike are you riding & what shocks does it have? Whatever it is start with the recommended settings for your weight then play around, noting the changes & difference felt.
T
I know in the ideal world it should come back set up the same but working better.
We put a lot of trust in our equipment and put a lot on the line. Don't trust anyone and check things yourself.
Unfortunately bikes coming back with altered settings and bodgy work is far too common after a service.
I have had shops tell me they ran out of the same weight oil so they put a heavier weight in. End result was it was unusable as there was not enough adjustment range to correct for the change in oil.
Settings reset to zero is unfortunately all to common.
I had one fork rebuild which threw me off my bike at Thredbo. Bike felt fine in car park and down stairs but soon found out beyond 4" of travel it became a pogo stick. They had completely overfilled the oil bath which meant the fork had nowhere to compress into. Result was the air got compressed and the fork turned into a combined coil with massively progressive air spring at the bottom of the stroke. The stack cost me three months off my bike. Front wheel departed from the ground part way round a corner and got spat down a bank.
Have also had a shop decide to raise my bottom bracket height on a FR/AM bike and also change my brake and shifter locations and angles to almost horizontal to a common XC setup. The reason the bike was in the shop had nothing to do with these components.
A mate who's 105 kg had his tyre pressures reset during a service which didnt involve the tyres or wheels to 20psi and dented his rims riding to the car. He normally runs 35-40. The shop at least got him new rims.
My chain rings have fallen off on the first ride after a shop replaced them.
Shops have regularly also over tightened things stripping thread.
I have had a new XO rear DR from a warranty claim snap on the first ride as the shop didn't allow for the travel of the bike when they put it on. I even asked the shop did they check it for the bike travel when I picked it up. When they replaced it they also tried to charge me to repair the damage they caused when the stripped the thread putting the warranty repair DR on. I also lost the bike for another week as they first tried to blame the breakage on the DR and make another warranty claim. SRAM politely told them where to go and confirmed they were at fault.
Fixing the left brake from leaking twice after the tag on the bike and shop docket said right brake. Third time lucky I guess.
If you need help with shock setup learn from someone else, get them to jump on your bike if they are around the same weight but realise user preference and your local trail plays a factor.
The key thing is to write down your settings and try small changes on the same track. Then check these changes on other tracks. Keep the settings and subjective comments in a notebook.
Only make small changes between test rides. When you are starting out it is difficult to know what the dials do. So long as you write the settings down make some big changes and bounce on the bike on the spot to feel the differences. Then back off to a small change and ride.
Agreed, don't be scared to play with settings, but little by little. Holy cow Simon what bike shope do you get your work done at... Butcher Brothers Cycles. That is some terrilble mistakes
Nearly every local bike shop i've been to for service work has been similar. Exceptions would be BA at North Manly and CBD in Kent St city. I'm sure others would have stories though.
Thats why i'm like Simon, DIY for most stuff on my bikes
Sames, I do a lot of work myself too, (I finally got a bike work stand,,,, sooooo good) but I leave any shock / fork building, re tuning etc to the experts. When I do take a bike to have any of this done I always get them to give the bike a tickle up at the same time and it always comes back just running just that bit sweeter. Never had a bad experiance in I guess ten years.
and so won't be mentioning any shop names.
My summary was from experiences at a number of shops. Some still exist others don't. Some have been great since and compensated me for the issues.
The key thing I have learnt is to be wary and check things out, ideally before you drive home. Even better do the work yourself when you can. Some shops also now lend me tools when I need them.