Results 1 to 17 of 17
  1. #1
    mtbr member
    Reputation: millertm's Avatar
    Join Date
    Jul 2012
    Posts
    461

    Chainstay vs. Wheelbase

    My question is this, how does wheelbase come into play on bikes that have a static chainstay length. For my XXL Carve (2012) I have a 442mm chainstay and wheelbase of 1154mm. Therefore, ~38.3% of wheelbase is chainstay. On a 17.5" frame, 442mm CS and 1085mm WB, or 40.7% WB is CS. I have heard it said that short CS bikes turn with hip input and I have noticed this as well on my bike. However, with a 17.4" CS my bike is not considered to have a short CS. But since I have a longer WB, should my bike have a better turn in then say a 17.5" Carve?

    Mark
    2012 XXL Carve Expert

  2. #2
    29er
    Reputation:
    Join Date
    Apr 2010
    Posts
    835
    Just a theory. But i think it has more to do with the relationship of the distance of the rear axle to your hips. You have to try >16.8" stays. And you will really feel it

  3. #3
    rr
    rr is offline
    I don't do PC
    Reputation: rr's Avatar
    Join Date
    Dec 2003
    Posts
    7,415
    Your over thinking the whole short chainstay thing, too many folks drinking too much koolaid!

    It's more about the wheelbase, of course the smaller size frame is gonna be a little more nimble and turn quicker cause it has a shorter wheelbase. Bike fit and other variables are gonna affect handling more than short stays, they are just a means to an end.

  4. #4
    mtbr member
    Reputation: millertm's Avatar
    Join Date
    Jul 2012
    Posts
    461
    Thanks guys, I have seen that some bike builder vary the CS on different size bike (BMC) while others do not. It got me thinking about CS % of WB for some reason.

    Mark
    2012 XXL Carve Expert

  5. #5
    mtbr member
    Reputation: Ottoreni's Avatar
    Join Date
    Jan 2004
    Posts
    1,013
    If you just look at the bottom part ....so much going on ...
    Chainstay versus effective chainstay.

    Bottom bracket drop, more drop = more feeling of in the bike...but to much equals too many pedal strikes.

    front to center is also an important consideration....

    And I am coming to realize that reach is a crucial measurement for frames ..

    As someone mentioned, short CS are nice, but ONLY part of the handling....
    You cannot go against nature, because when you do, its part of nature too.

  6. #6
    mtbr member
    Reputation:
    Join Date
    Jun 2008
    Posts
    1,194
    Front Center is the important measurement....

  7. #7
    mtbr member
    Reputation:
    Join Date
    Aug 2011
    Posts
    1,408

    Re: Chainstay vs. Wheelbase

    What is front center exactly?



    Sent from my MB865 using Tapatalk 2
    2012 Scott Spark 29 Team
    2013 Scott Scale 970
    2011 Scott Speedster S20
    1999 Specialized FSR Comp

  8. #8
    mtbr member
    Reputation: Ottoreni's Avatar
    Join Date
    Jan 2004
    Posts
    1,013
    Quote Originally Posted by zephxiii View Post
    What is front center exactly?


    Front-Center is the horizontal measurement from the center of the BB shell to the front wheel axle. In my experience, frames with short FC feel endo prone and you feel over the front wheel.

    Reach I find also to be crucial. A frame with a short reach measurement makes you feel as if you are over the bars when standing. Not good for tech riding IMO.

    Somehow, I am beginning to belive there is an inverse relationship between reach/FC and chainstay length. Just can't put my finger on it....
    You cannot go against nature, because when you do, its part of nature too.

  9. #9
    mtbr member
    Reputation:
    Join Date
    Jun 2008
    Posts
    1,194

    Idea!

    Waltworks Bicycles: Search results for front center

    Walt explains it much better than I could.....

  10. #10
    Registered text offender
    Reputation:
    Join Date
    Dec 2011
    Posts
    1,146
    I'll have to take measurements when I get home, but the wheelbase of my two bikes are very close. The one with the shorter chain stays and longer front center feels more intuitive to ride. I don't have a definite stance on this, but my preference is more rearward bias and I would like to see more manufacturers get away from the one stay length for different size frames.

  11. #11
    mtbr member
    Reputation:
    Join Date
    Aug 2011
    Posts
    1,408

    Re: Chainstay vs. Wheelbase

    Interesting indeed, i was never aware of this measurement and will compare the bikes I've been on.


    Sent from my MB865 using Tapatalk 2
    2012 Scott Spark 29 Team
    2013 Scott Scale 970
    2011 Scott Speedster S20
    1999 Specialized FSR Comp

  12. #12
    mtbr member
    Reputation:
    Join Date
    Nov 2010
    Posts
    331
    Wheelbase and where your c of g is in relation to that is about all that matters, the rest may be over-thinking it. eg if you have a longer chainstay bike but it has a short reach, you can still get your weight over the back axle for drops, manuals etc. Some bikes balance front-rear centers better than others but there's so many things to influence that - head angle, bb drop, bar to rear axle relationship / distance etc.

    With singlespeeds I've owned, I've never really felt that changing the front-rear centre balance by adjusting the EBB on a bike makes much difference, if any, but adding wheelbase as well as chainstay length via a slider dropout felt a bit more odd. So I'd say that a fixed wheelbase / a constant relationship between the wheels and bars may be a good thing.

  13. #13
    reading comprehension wat
    Reputation: dv8xin's Avatar
    Join Date
    Mar 2013
    Posts
    329
    I've wondered something similar. I'm 5' 7" and think 17.5" Treks (like the Superfly 100) are the most balanced bikes I've ever ridden. It's as if they pay a lot of attention to the front center and rear center (RC, AKA chainstay length) ratio, in relation to the wheelbase. Trek calls 17.5" (445mm) RC/chainstay short on 29ers. I also ride a med Yeti 26" 5" FS trail bike with 16.9" RC and think that's super balanced as well, maybe a touch more rearward biased. I rode a small Giant Reign X, and it feels rather off-balance. Even though it was size small (front was shorter) it felt significantly more rearward biased than another bike with similar travel and 16.9" RC, that or my movements on the bike caused it to feel that way, or the rear DHX Air 5.0 wasn't set up to be well balanced with the front 36 TALAS. It felt like its wheelbase was really short and unstable, making me appreciate the Trek and Yeti more. I wonder if extending the RC for bigger riders on bigger sized frames would help give taller riders that balance, comfort, and handling traits that shorter riders feel. If only people could swap their consciousness to different framed bodies to test the theory out.

    The balanced bikes felt like they were great for longer rides, being far more comfortable. I was happily doing 20-30 mile rides on 'em, on a regular basis, with some 3.5+ hour epics on occasion On the shorter bikes, it would just be fun to hammer out of the saddle and try to freestyle, getting air on all the little bumps, doing a feel wheelies and manuals sprinting out of corners and over stuff riding maybe 7-14 miles, trying to kill it on the 1 hour loop, with 20 mile rides feeling like epics. The tires played a role too, in figuring what distances and terrain each bike was happy on. Long wheelbases and grippy tires were ground hugging speed demons, really fun on big mountain stuff, plowing through rock gardens and going scary fast down loose wide descents. Shorter wheelbases with grippy tires were corner carvers (ex. Giant Reign X with Nevegals), great for tight twisty stuff. They sort of had personalities, more in relation to the wheel base length and tires. On climbs, the long RCs (chainstays) seemed to feel more planted far easier to climb and the shorter RCs were harder to climb, forcing you to move further up the saddle to keep the bike going straight and to keep the front wheel on the ground.

    As far as fit goes, you really can't look at just a few numbers. The more you know, the more you feel inclined look at all the numbers and how they're related. Even more work for people in between sizes. For shorter folk looking to fit on a 29er, I think stack (BB to top of head tube) is a huge number to watch out for. A long head tube, long axle to crown, steep HA, long travel fork, low BB, and maybe tall headset cups (or a lefty's dual crown) can contribute to a high stack height. I've noticed that I fit better on 29er HTs with BBs that are 12.5" or higher, 100mm or shorter head tubes, integrated or ZS headsets, 100mm travel or less in the fork, 68.5 to 70 HA, etc. to get stack close to 600mm. Combine that with a specific reach and ETT ratio, to get the handlebars in a familiar spot. Where FC and RC fits in still confuses me. If I knew more, rode a few more bikes to get a feel, I feel as if I'd be coming a step closer to getting a custom Ti bike from Steve Potts or something, as I have found my perfect fit. For now, I'm just gonna rely on the geo from the big names to get the gist of how it all works. I know there's even more to consider, like tubing how its dimensions and shaping play a role in ride feel, front end stiffness, lateral stiffness, and vertical compliance, etc., but that's another topic.

    Not sure why this is under 29er components, but I'm thinking about a Niner frame and I love how they offer super detailed geo charts. I'm comparing them to the big name brands on paper, then plan on test riding to confirm. I can then figure out a nice spec suited just for me, such as a Syntace Flatforce stem in case I decide to go Med instead of Small. I kind of like how Niner's small isn't super small and would actually fit me decently, compared to the others' small/15.5 frames. Seeing a really poorly detailed geo table like Santa Cruz's turned me off, but I admit their engineering is rather good. I also have to mention that I choose frames based off what components they take, like PF30 or BSA BB shells (English threaded 73mm), 44mm upper and 56mm lower tapered headtube for ZS headsets, 15.5" - 16.5" seat tube to fit a 30.9 or 31.6mm 380mm length dropper post, dropouts (142x12 TA or 135x10 QR), standard 1 1/8" stem clamp, etc, FD clamping, cable routing, water bottle mounts, rear tire clearance, low q factor crank and heel clearance, etc.

    I know I wrote a lot and someone's gonna say, F that, "just test ride", but I feel to really understand a bike and quickly and easily learn its traits and adapt to it, you need to know a lot more. Treks climb really well and descend far better than you'd expect and have a great amount of behaved predictability and control that gives great confidence, yet don't have that super stiff and quick responsive feel that you normally would related such traits to. Such results don't really come from specific geo numbers, but can sort of be simplified by some by saying that's the G2 geo at work and the frame tubing and stiffness tuning giving it that ride feel, with the long wheelbase giving stability, and longer fork offset reducing trail to make steering quicker, to give familiar steering control with the stability of a bigger longer travel bike, but at a much lower weight. Yeti does some magic with their frame tubing and geo too, with great front end stiffness and a more responsive frame [than Trek] that gives great feedback, making you want to be more aggressive, yet feels lean enough to be racy. Can't really explain that with geo chart numbers. Seeing new stuff like Mondraker's forward geo and how well it's being received (tech intro/propaganda) just drops another monkey wrench into the works. Maybe taking a cue from this and Yeti's long top tube (and front center) + short stem, I'll opt for a Med Niner and stick a short stem on it.
    Last edited by dv8xin; 03-16-2013 at 05:11 PM.

  14. #14
    mtbr member
    Reputation: Saul Lumikko's Avatar
    Join Date
    Oct 2012
    Posts
    1,167
    Just some uneducated speculation that could be cerebral flatulence: when you turn the handle bars, the front wheel guides the bike off from the straight path it would otherwise go, and the rear wheel acts as a pivot point. Anything in between moves sideways: more at the headtube, less at the BB and by the time we reach the rear axle the sideways movement is zero. As an extreme example: if you were to turn the front wheel sideways and somehow make it move, the rear tire would rotate in the centre of the circle drawn by the front tire. The closer to the pivot point your CoG is, the quicker you will be able to change direction. For this reason shortening chainstays to tuck the rear tire under the rider makes the bike more nimble - it's not only about wheel base.

  15. #15
    beater
    Reputation: evasive's Avatar
    Join Date
    Feb 2005
    Posts
    3,623

    Chainstay vs. Wheelbase

    Quote Originally Posted by Yogii View Post
    Waltworks Bicycles: Search results for front center

    Walt explains it much better than I could.....
    Good write-up. Thanks for posting it. I've never read Walt's blog before, but I'll add it to my bookmarks.
    "Back off, man. I'm a scientist." - Dr. Peter Venkman

    Riding in Helena? Everything you need to know, right here.

  16. #16
    mtbr member
    Reputation: bholwell's Avatar
    Join Date
    Oct 2007
    Posts
    2,100
    Quote Originally Posted by Saul Lumikko View Post
    Just some uneducated speculation that could be cerebral flatulence: when you turn the handle bars, the front wheel guides the bike off from the straight path it would otherwise go, and the rear wheel acts as a pivot point. Anything in between moves sideways: more at the headtube, less at the BB and by the time we reach the rear axle the sideways movement is zero. As an extreme example: if you were to turn the front wheel sideways and somehow make it move, the rear tire would rotate in the centre of the circle drawn by the front tire. The closer to the pivot point your CoG is, the quicker you will be able to change direction. For this reason shortening chainstays to tuck the rear tire under the rider makes the bike more nimble - it's not only about wheel base.
    Good point, and sound physics. Here's another idea, which in theory could be more important to cornering at speed: To initiate a turn one must first lean the bike. In order to lean the bike, one must first countersteer, and of course the bike must pivot from the contact patch. The lower the center of gravity, the faster the turn-in.

    If you have a dropper post, this is a fun experiment: Take a tight twisty section as fast as you can with the post up, then repeat the section with the post down and your body as low as possible. It's really amazing how much responsive the bike feels, and how much more (perceived, maybe) control you gain.
    Tire Design & Development Engineer. The opinions expressed in this forum are solely my own.

  17. #17
    beater
    Reputation: evasive's Avatar
    Join Date
    Feb 2005
    Posts
    3,623

    Chainstay vs. Wheelbase

    Quote Originally Posted by bholwell View Post
    If you have a dropper post, this is a fun experiment: Take a tight twisty section as fast as you can with the post up, then repeat the section with the post down and your body as low as possible. It's really amazing how much responsive the bike feels, and how much more (perceived, maybe) control you gain.
    This is something I wish more people understood. If you think a dropper post is only for making it easier to get behind the saddle on steep descents, you're missing well more than half the value, IMO. Like most people who say they have no use for one, I never had a problem sliding behind it even at full height either, although getting back in a G-out could be interesting. But leaning the bike over while maintaining weight distribution generally requires slamming the saddle.
    "Back off, man. I'm a scientist." - Dr. Peter Venkman

    Riding in Helena? Everything you need to know, right here.

Similar Threads

  1. Wheelbase
    By JTBAZ in forum Turner
    Replies: 2
    Last Post: 05-11-2012, 01:17 PM
  2. Mach 5 wheelbase?
    By HHMTB in forum Pivot Cycles
    Replies: 4
    Last Post: 05-07-2012, 12:19 PM
  3. wheelbase
    By fishercat in forum Ibis
    Replies: 1
    Last Post: 12-18-2011, 06:10 PM
  4. wheelbase
    By rich1374670x in forum Beginner's Corner
    Replies: 4
    Last Post: 08-05-2011, 02:28 PM
  5. '09 Large Flux wheelbase
    By dhd in forum Turner
    Replies: 0
    Last Post: 02-10-2011, 04:54 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •