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Pedal bob

dogboy73dogboy73 Posts: 440
edited June 2010 in MTB workshop & tech
I'm getting a little pedal bob from the rear shock (RockShox Monarch 2.1) on the rebuild. I've tried adding more air but it doesn't seem to be helping to cure the problem. Just wondering if there is anything else I can do to help the problem or if I should have gone for a shock with compression damping? Could my first upgrade to the rebuild be on the cards a week after I finished it?! :D
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  • peter413peter413 Posts: 5,120
    Try relearning your peddaling technique
  • dogboy73dogboy73 Posts: 440
    peter413 wrote:
    Try relearning your peddaling technique
    Really?! Not quite the answer I was expecting. I guess things have been a tad different with those clipless pedals.
  • RevellRiderRevellRider Posts: 1,794
    peter413 wrote:
    Try relearning your peddaling technique

    Useful post.

    I'm sure the only Monarch rear shock that was available after market was the 4.2? Could it be that the internal compression settings aren't for a single pivot bike?
  • supersonicsupersonic Posts: 82,708 Lives Here
  • RevellRiderRevellRider Posts: 1,794
    I'm gonna guess his Ellsworth Isis, it has photos of one running a Rock Shox shock in his sig link
  • supersonicsupersonic Posts: 82,708 Lives Here
    If it is the ISIS then you'll find certain gears bob more than others. And yes, not stomping can help lol.

    Compression damping adjustment is always useful.
  • joshtpjoshtp Posts: 3,966
    you could try a pro pedal or sim r.shock, a smoother pedal action, or dif gears.. or live with it
    I like bikes and stuff
  • biff55biff55 Posts: 1,404
    peter413 wrote:
    Try relearning your peddaling technique

    WTF ?
    So speaks the world champ. :lol:
  • AnonymousAnonymous Posts: 79,667
    Pedalling technique can make a bigger difference than anything else, but some bikes are just more prone to it than others.
    You could get a rear shock with adjustable low speed compression damping, and crank it up until the bob goes away, but you will lose a degree of suppleness by doing that.
  • dogboy73dogboy73 Posts: 440
    ]I'm sure the only Monarch rear shock that was available after market was the 4.2? Could it be that the internal compression settings aren't for a single pivot bike?
    I have the Monarch 2.1. When I bought this the 3.1/3.2 & 4.2 was also available. Just checked on CRC & they only sell the 4.2 at this time. The Fox RP23 was recommended to me by Tony Ellsworth but at the time I didn't have the cash for one of those.
    Pedalling technique can make a bigger difference than anything else, but some bikes are just more prone to it than others. You could get a rear shock with adjustable low speed compression damping, and crank it up until the bob goes away, but you will lose a degree of suppleness by doing that.
    This might be an option I'll have to investgate. Maybe a Fox RP23 would be the way forward to control things more precisely. I could sell the Monarch as it's only been used for about 10 miles of riding at the moment. Still got the box as well :wink:
  • AnonymousAnonymous Posts: 79,667
    Buy one from TFTuned, and they'll set it up for you and your bike
  • dogboy73dogboy73 Posts: 440
    Buy one from TFTuned, and they'll set it up for you and your bike
    Not a bad idea. I used TFtuned for the hardware kit. Great company to deal with. I might contact them for some advice. In the mean time has anyone got any shock recommendations? Actually given the Orange Five Pro is a similar design to the Isis (i.e. single pivit swingarm) I might just ape what they come with, which I think is a Fox Float 23 with Pro Pedal.
  • AnonymousAnonymous Posts: 79,667
    Similar designs can be misleading. A very slight change in the pivot location can completely transform the bob characteristics. A few mm higher (than some arbitrary "ideal" placement), and the pedal action will try and lift the bike hopefully reducing bob. A few mm lower, and the pedal action will actually try and compress the suspension, making the bob effect worse.
  • dogboy73dogboy73 Posts: 440
    Similar designs can be misleading. A very slight change in the pivot location can completely transform the bob characteristics. A few mm higher (than some arbitrary "ideal" placement), and the pedal action will try and lift the bike hopefully reducing bob. A few mm lower, and the pedal action will actually try and compress the suspension, making the bob effect worse.
    This is true. I guess the best shock in the World on the wrong bike & suddenly it might not even work that well! Fine art this shock selecting & tuning. I've got some homework to do here. In the mean time I'm going add yet more air to the shock, speed up the rebound adjust a little & see if I can iron out any bob as best I can. I might seek some advice from Mr.Ellsworth himself as well. He has been very helpful through out the rebuild. Nice of him to take the time to reply to my enquiries. Top bloke. Owe him a pint :wink:
  • cooldadcooldad Posts: 32,599
    Hardtail
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

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    Parktools
  • dogboy73dogboy73 Posts: 440
    cooldad wrote:
    Hardtail
    My very next rebuild project will be an 8/9 speed hardtail :wink:

    In the mean time I've added some more air into my shock & messed around with the rebound setting a little to try & get a balance between bob & bump response. The bob isn't that bad & the bike is feeling great & very smooth over the local bumpy stuff (which isn't that bumpy it has to be said). I'd be interested to hear from other single pivot owners (Orange Five for example) to see what they have to say about shock performance. I think some additional compression control on the shock would help me. Might have to looks at alternatives in the future.
  • supersonicsupersonic Posts: 82,708 Lives Here
    You will never eliminate bob entirely without 100% lockout. Just so many variables.
  • cavegiantcavegiant Posts: 1,546
    The mongoose suspension system effectivly eliminates it when pedaled smoothly
    Why would I care about 150g of bike weight, I just ate 400g of cookies while reading this?
  • AnonymousAnonymous Posts: 79,667
    cavegiant wrote:
    The GT suspension system effectivly eliminates it when pedaled smoothly
    there, fixed it :lol:

    The Idrive is superb, but like sonic syas it doesn't eliminate it, it just seriously reduces it.
  • dogboy73dogboy73 Posts: 440
    I get very little pedal bob on my Giant Trance. The Maestro suspension system is superb.
  • AndyAndy Posts: 8,207
    All the suspension systems are well designed and give little pedal bob. Fact is, they all still do to some degree.
  • AnonymousAnonymous Posts: 79,667
    True. Try riding a cheap supermarket special full suss, then you'll realise what pedal bob is!
    The bobbiest bikes I've tried are Konas - I'm not a fan of their system at all.
  • dogboy73dogboy73 Posts: 440
    True. Try riding a cheap supermarket special full suss, then you'll realise what pedal bob is!
    It's so bad on those it looks like pedal bob is part of the design!! :lol: Terrible things.
  • captainflycaptainfly Posts: 1,001
    cavegiant wrote:
    The mongoose suspension system effectivly eliminates it when pedaled smoothly

    Really? I must be worse at pedaling than I thought, thought :roll:
    -_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_
    Mongoose Teocali
    Giant STP0

    Why are MTB economics; spend twice as much as you intended, but only half as much as you wish you could afford? :roll:
  • diydiy Posts: 6,473
    supersonic wrote:
    You will never eliminate bob entirely without 100% lockout. Just so many variables.

    I thought that, when I switched from an old Fox RL to the RP23. I only have my propedal set on medium and I get no power sapping bob at all. It does move a little, but importantly not in time with the pedal, which is key.

    A lot of what l do is hill climbs and it is hard to consistently pedal in circles when you've been mostly climbing for 2 or 3 hours.

    IMO Pro pedal is as good as lock out for reducing bob. You do have to adjust your seat though, to compensate.
  • dogboy73dogboy73 Posts: 440
    diy wrote:
    supersonic wrote:
    You will never eliminate bob entirely without 100% lockout. Just so many variables.

    I thought that, when I switched from an old Fox RL to the RP23. I only have my propedal set on medium and I get no power sapping bob at all. It does move a little, but importantly not in time with the pedal, which is key. IMO Pro pedal is as good as lock out for reducing bob. .
    I think a better shock, like the Fox RP23, that has more adjustment has got to be a good thing for this sort of thing as well as tweaking the settings for each bike it might end up attached to. Could'nt really afford an RP23 when I was doing the rebuild (it costs around 3 times as much as the Monarch 2.1 I bought) so I guess I'll just have to go with it.
    You do have to adjust your seat though, to compensate
    How do you adust the saddle to help improve things with pedal bob?
  • diydiy Posts: 6,473
    Set the height and level of the seat taking into account of the active sag of the rear shock. Its a difference of maybe 10-15mm height, a few degrees down on the nose and 3-4mm forward. Weather or not you prefer it set for active or static, is probably down to personal choice, the type of riding and the shock. On my RP23 I set it for static, because it has pro-pedal. On something softer your might go towards active.

    Part of the issue of pedal bob is the effect of the shock compression on your legs when you are turning the pedals.

    Also keep your cadence high when climbing (obviously on some hills you simply can't do that), you could slow the shock rebound too, if that is adjustable, but then we are starting to tune the shock for climbing when you probably want it tuned for decent.
  • John.TJohn.T Posts: 3,698
    I can not see how saddle height will make any difference unless the BB is on the swing arm. On my Santa Cruz Superlight the saddle is at the top of the seat tube and the BB is at the bottom. Neither are going anywhere.
    It is fitted with a Fox RP23 and it all just works. I never need the Pro-pedal unless I am getting out of the saddle. The whole set-up is so good that I forget it is there until I check the travel marker at the end of a ride and find I have been getting full travel.
    Pedal bob due to body movement bob when out of the saddle (and in if you are not too smooth) can be controlled to some extent by using a gear that turns out of frequency with the bob. Bob when seated can be helped by using a gear that tends to extend the suspension a little under chain load. This will usually be on the middle ring.
  • diydiy Posts: 6,473
    Agree, but we were talking about when you don't have an RP23 or similar. My comments were mainly about climbing when you don't have a shock with lock or pro-pedal.

    Seat adjustment makes a difference on steep climbs, because as the shock compresses the gap between the seat and the rear axle gets shorter, so you end up with the seat nose in the air which pushes you back in the seat and affects how you pedal and also how effectively you can climb, but also how the body mass affects the shock.

    on a MB seat height is not just about the optimum difference between the bb and the seat for the length of your legs, there are other control factors to consider.

    When you say you don't need pro-pedal while in the seat, are you saying you leave the valve open all the time?
  • supersonicsupersonic Posts: 82,708 Lives Here
    As before, it depends on the sus design - some may extend, not compress under power. But working with what you have can pay dividends.
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