Single-Speeders … Seat angles/Power transfer ?

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  • Single-Speeders … Seat angles/Power transfer ?
  • qwerty
    Member

    my knees were not happy after riding SSEC2010 on a CX bike with too big a gear – but then nor was any other part of my body!

    😀

    seanoc
    Member

    I used to find that on my Simple (73 degree seat angle); on prolonged, moderate climbs I'd pump up them seated but always felt like I was pushing forwards. Slamming the saddle all the way forward gives a pseudo-steeper seat tube which puts your centre of mass further over the cranks and makes you push forwards less and downwards more. I've since ditched the 120mm forks and stuck on a pair of rigids which has helped again.

    I think Brant is bang on with his new puppies.

    matthewlhome
    Member

    I would recommend standing up rather than mashing sat down. eases the pressure on the knees.

    Do you have lower gearing on the road bike perhaps?

    Premier Icon miketually
    Subscriber

    I think Brant is bang on with his new puppies.

    Funny you should say that…

    nixon_fiend
    Member

    This is a question for the bearded ones …

    What is your SS seat-tube angle – and do you notice the difference?

    I have a SS road bike and MTB and find that my legs feel so much better putting power into the Road bike. Comparing the two on my commute, by the time I get home (I live on the top of a big hill..) my thighs feel good in a tired-muscle sorta way on the Roadie bike .. but putting on the power on my MTB I get broken feeling knees! But my legs don't feel as 'used' – it's as though my knees have taken all the strain.

    I tend sit down and pump away than stand up and mash the pedals

    Was wondering about geometry and the main difference is a steeper Seat Angle on the road bike … so I wondered about buying an MTB frame with a much steeper st.

    Anyone else had a similar experience? Or made the same connection .. I'm curious.

    Dave m

    nixon_fiend
    Member

    Gearing is higher/harder on my roadie bike but I can put the power in as hard as I like and never/rarely have achy knees. The MTB has a 72.5 deg ST angle and the road bike 74.5

    I notice dialled bikes have a nice steep 74 deg ST angle.

    ojom
    Member

    I think Brant is bang on with his new puppies.

    *concurs*

    thomthumb
    Member

    i like the seat angle slack. got a layback post and the seat all the way back on the rails.

    I like to push from behind the pedals rather from above.

    nixon_fiend
    Member

    thomthumb – you ride SS like that? what sort of ratio?

    _tom_
    Member

    I like to push from behind the pedals rather from above.

    I absolutely hate the feeling of this for some reason. I have to be above the pedals otherwise it just feels really weird.

    Premier Icon miketually
    Subscriber

    I find a slack seat angle to be good for spinning along. If the trail's going up, I'm standing anyway so the seat angle doesn't matter.

    Have you checked the distance from pedal to top of seat,

    I was thinking the same thing about a year ago between my mtb and CX bike both SS. After a few checks i realised my seat on my mtb was about 15mm lower I now run them both the same.

    nixon_fiend
    Member

    ^ Saddle height is fine, I find a lower height is better for my knees (higher = slacker!)

    But I don't want to turn this into a thread about my knees 😛

    Genuinely interested on SSers ST angles

    keavo
    Member

    i prefer steep a seat angle, i think its a more powerful position. i don't get knee pain but do get back pain if my seat is too far behind the bb.

    Premier Icon thekingofsweden
    Subscriber

    I have no idea what you are talking about !

    thomthumb
    Member

    thomthumb – you ride SS like that? what sort of ratio?

    yeah. 32:18 on 29"

    just rotates me around the BB a bit, the opposite to a TT type position if that makes sense

    JoB
    Member

    layback post and the seat all the way back on the rails here too, on all bikes – road, mtb, cx – geared or SS

    i like to push from behind the pedals rather from above, maybe it's a roadie seated climbing thing

    Premier Icon epicyclo
    Subscriber

    When I'm working hard I'm nowhere near the seat.

    Premier Icon Del
    Subscriber

    as well as seat height and position, is there a difference in crank length?

    Premier Icon ononeorange
    Subscriber

    Would say (as above) that standing up is the difference. I couldn't ride my s/s up very much without standing out of the saddle.

    Premier Icon BigJohn
    Subscriber

    How about the difference in hand position between the 2 bikes? If your upper body is pitched further forward on the road bike that is going to make a huge difference to the overall dynamics.

    Note: I have 2 bikes, a road bike (fixed) and a Cotic Soul which I ride mostly SS. When I have it geared, I shove the seat a lot further forward. That's because I like the seat back for putting the power down on SS, but the front end will just lift if I go up hills in a low gear when it's got gears on.

    Premier Icon scaredypants
    Subscriber

    If you stay on the saddle I can't see why it'd make any difference to your knees what your seat angle is *in isolation*

    For both bikes to be the same, the angles and distances between BB, saddle and bars are what's relevant aren't they ? Since the MTB probably has a higher front end, you "need" to be rotated backwards a bit to maintain the same overall position – which would require a slacker ST angle.
    Once you stand up, this changes and the above also doesn't apply to bike-handling and weight distributiuon – but you're talking about riding roads on a commute I think, where it'd be less important (and irrelevant to your knee pain when seated)

    Course, it's possible that the 2 bikes are not the same angles/distances and that the road bike fits you better

    Premier Icon epicyclo
    Subscriber

    What's more important IMO is using drop bars because these give you a wider range of position and seeing as chucking your weight around is used to help climb, it's got to be worthwhile.

    poppa
    Member

    Do you have a layback post on the MTB? You could try swapping it for an in-line if you do.

    poppa
    Member

    Oh… and my old bike had a lot slacker seatpost angle than my new one. The most noticable advantage of a slack seatpost angle (IME) is that when you go into 'attack' mode hovering off the saddle, the saddle is further back wrt. your body and hence more out of the way.

    james-o
    Member

    interesting post. the traditional roadie wisdom (that i agree with from experience) is saddle back / slack angle for low cadence and power, saddle forward for spinning a smaller gear.

    the Flyer has a 74.5 degree SA and the iO has a 73.5-74 SA as seated SS pedalling tends to be brisk cadence and spinning, as soon as you need power or cadence slows you tend to get out of the saddle. so i'd say steeper is better for SS. there's possible trade-offs, too steep on or off road and day-ride position isn't as comfortable and front-centre / saddle-bar reach is trickier to balance, but i'd agree climbing in a seated-compatible gear on a geared bike is generally improved due to weight distribution.

    Premier Icon glenh
    Subscriber

    interesting post. the traditional roadie wisdom (that i agree with from experience) is saddle back / slack angle for low cadence and power, saddle forward for spinning a smaller gear.

    That explains why I like inline posts and the saddle forward then. I can't sit and push a big gear for the life of me. Spinning fast or out of the saddle for me.

    J0N
    Member

    I ride my Flyer like a TT bike. Seat is nearly as far forward as possible and I sit quite far forward on it.
    I ride my mtb with so may seat heights that I dont really think about it but when climbing I like to be over teh pedals to its saddle up and on the nose.

    OT james-o: Is it possible to buy a shorter more angled (lower) genesis stem for my flyer?

    Premier Icon miketually
    Subscriber

    *thread resurrection*

    Took this last night and thought it illustrated my seat angle preferences quite well – layback seatpost and saddle right back on the rails.

    ooOOoo
    Member

    I'm with you on this – I need to feel I'm behind the pedals, to get the power down.

    All these steep seat angle bikes now are fine for that 10% of the time spent climbing, but seem worse for the 90% of time on the flat or DH

    And why are BBs always in line with the seat tube?

    And why are BBs always in line with the seat tube?

    Cos it makes a nice triangle?

    cynic-al
    Member

    I spec'd a really lack seat angle on my ss and regret it a bit

    Premier Icon miketually
    Subscriber

    And why are BBs always in line with the seat tube?

    cutting it 2

    ooOOoo
    Member

    Hey not seen that before!
    Great, but they've moved the BB the wrong way for me 😉

    Premier Icon Onzadog
    Subscriber

    I don't ride single speed but I did ride someone elses bike recently that was very relaxed and I really didn't get on with it.

    I knopw there's no actual reason to use the KOPS system when setting up a bike but it does make it much more comfortable for me.

    Tasso
    Member

    My Robin Mather SS MTB frame has steep seat and head tube angles – can't remember what exactly but Robin did raise his eyebrows and ask if I was sure at the time. Love the bike as it climbs well for me that way.

    In hind sight a slightly less steep head tube would have been sensible for descents but it's entertaining and super speedy in sweeping singletrack…but I digress.

    Recently bought a Dialled PA and this too appears to be steep angled compared to some other frames out there (coming over from an Inbred and comparing Soul and P7 before purchase) and again I particularly like the way that climbs.

    Also had a Pompino in the past and that felt great running SS/Fixed on and off road but then the seat tube angles probably not that different to my preferred HT MTB geometry.

    So I think it does not matter really if it is SS or geared but more what you like or you are used to.

    Tasso
    Member

    Oh, another thing I notice is that transfer from seated to standing (which happens lots on the SS mtb for me) is slightly less effort with the steeper seat angle.

    This is particularly noticable towards the end of long rides, thinking dusk til dawn etc. That must translate into using more body english all the time though.

    james-o
    Member

    "OT james-o: Is it possible to buy a shorter more angled (lower) genesis stem for my flyer? "

    we used to stock spare stems but didn't use enough to justify it sorry.. i may have a shorter 100mm silver one lying around if that's what you need?

    a note about KOPS theory – read Keith Bontrager's 'KOPS – Debunking the myth' if you're interested in bike fit, it's a detailed but sound argument. worth reading before buying a custom frame anyway..

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