Viewing 32 posts - 1 through 32 (of 32 total)
  • Long, low and slack, but too low?
  • bfebikerchap
    Free Member

    Afternoon, it’s Friday and I’m all alone at work so here’s what I’ve been thinking about…
    I love my Bird 120lt, but the bb is low, the number of pedal strikes and times I’ve whacked a toe is high. I’m conscious of timing my pedal strokes, but it does make climbing over roots or rocks a chore. What to do? Shorter cranks? Less sag? 120mm linkage? Has the modern geometry gone too far?

    Answers on a post card…

    submarined
    Free Member

    How long have you had it? Took me a while to get used to my Patrol, but now I have, I wouldn’t want to go back, and I hardly ever clip a pedal.

    geex
    Free Member

    I’m conscious of timing my pedal strokes

    Try using that consciousness along with coordination, timing, common sense and forward planning.
    your bike’s BB isn’t particualrly low

    Hope this helps

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    Blackflag
    Free Member

    Timing pedal stokes only goes so far. You can put shorter cranks on and that’s about it.

    So yes, for tech climbs then a BB can be far too low.

    geex
    Free Member

    your word for today blackflag is.

    “ratchet”

    I’ll expect your homework on my desk in the morning 😉

    Blackflag
    Free Member

    the answer isnt always “ride better” for any given question.

    You can watch those videos of guys on road bikes hopping up flights of steps all day long, doesn’t mean they are the best tool for the job.

    geex
    Free Member

    You can watch those videos of guys on road bikes hopping up flights of steps all day long, doesn’t mean they are the best tool for the job.

    Whatever gets you off man 😉

    thisisnotaspoon
    Free Member

    Learn to live with it. Bird are amongst the lowest but really bikes aren’t that much lower overall than they were 15 years ago. Even the lowest bikes (85mm drop on 29ers for example) is still an 11″ bb height which is low but wouldnt have raised eyebrows.

    Can someone explain the logic behind short cranks to me? Why would you want a 10mm lower bb and then 10mm shorter cranks?

    Blackflag
    Free Member

    Can someone explain the logic behind short cranks to me? Why would you want a 10mm lower bb and then 10mm shorter cranks?

    The lower BB height lowers the centre of gravity. The shorter cranks is an attempt to stop the pedals being too close to the ground at the bottom of the stroke. Two very different things

    CheesybeanZ
    Full Member

    Blackflag, stop feeding the troll.

    Blackflag
    Free Member

    Ha ha. I’m rubbish at spotting trolls. I believe everyone is fundamentally honest and loveable.

    geex
    Free Member

    I’m 100% honest and incredibly loveable.

    scotroutes
    Full Member

    The lower BB height lowers the centre of gravity. The shorter cranks is an attempt to stop the pedals being too close to the ground at the bottom of the stroke. Two very different things

    A shorter crank raises the CoG again though.

    geomickb
    Free Member

    Yes, I think so.

    I have a 2019 Canyon Spectral (MBR Trail Bike of the Year). It’s my first full-suspension bike and I hate it. I have to lock out the suspension when climbing or I constantly pedal strike. Even with it locked out, it still strikes.

    My previous bike was a 29er hardtail (Canyon Yellowstone) and could stride over anything without striking.

    Makes me wonder what the point is having FS (and carting the weight around), when I keep it locked out most of the time.

    Yes, I could ratchet more but why should I have to adapt my technique to make up for the bike’s failings?

    Mick

    joemmo
    Free Member

    I have a 120lt and yes it’s lowish but you’ll basically get used to it and stop whacking the pedals or at least do it less often. You could check your sag and shock setup too in case it’s a bit soft

    Blackflag
    Free Member

    A shorter crank raises the CoG again though.

    Not when the pedals are level it doesnt

    thisisnotaspoon
    Free Member

    Not when the pedals are level it doesnt

    I can see that, but is 5/10mm noticeable in a straight line?

    Most benefit comes from the lower CoG when cornering, when the crank will be 12 and 6.

    One of the benefits of longer cranks is they work better at lower Rpm, which in turn should make timing your pedalling easier.

    geex
    Free Member

    why should I have to adapt my technique to make up for the bike’s failings?

    Well that’s one way to look at the issue.
    Thing is though there are also many positives that come from a bike having a low BB and if you’ve intentionally chosen to buy a low BB bike it’d be pretty stupid not to adapt your technique to make the most of those positive traits. It’s actually not difficult and looking ahead, planning your line, timing pedal strokes and paying attention to foot placement will improve your riding everywhere.

    2019 Spectral’s don’t have what i’d consider an overly low BB height either. Repeatedly smashing your pedals and toes into stuff isn’t a failing of the bike it’s a failing of the rider.

    eddiebaby
    Free Member

    A shorter crank raises the CoG again though.

    Depends if your knees bend or not.

    iainc
    Full Member

    but geex, you like short cranks 🙂

    too short cranks are also horrible to pedal (especially if like me you also ride regular bikes every day).
    too short and they also become pretty horrible to whip and table with and they reduce stability when cornering outside foot down.
    Yeah. so other than their extremely horribleness short cranks are a great idea

    geex
    Free Member

    **** luv um 🙄

    You got your new leccy trundle bus yet?

    jamesoz
    Full Member

    Thing is from experience ratcheting only gets you so far, maybe look at shock set up?
    My current bike has a lower BB than the last but I pedal strike less, I put that partly down to a more supportive shock.

    iainc
    Full Member

    geez, next week hopefully…. getting impatient now !

    scotroutes
    Full Member

    Depends if your knees bend or not.

    If your knees don’t bend, BB height is the least of your worries.

    chiefgrooveguru
    Full Member

    Unless you’re very tall then you’ll probably be better off with shorter cranks – I have long legs and ride 165 and 170mm.

    It takes me a while to adapt to lower BB heights but once I have it’s always better on steeper trails, however rough they might be. Pedalling up does require timing and ratcheting.

    On flatter trails super low BBs can be annoying if they prevent you pedalling up to speed but they’re still nicer for cornering.

    Neither of my current bikes are crazy low but they’re still fairly low, at around 290mm at sag.

    pembo6
    Free Member

    I had a similar problem with my full sus. I’ve moved to 165 cranks (which I actually prefer), 10mm longer fork (now 160mm, which I had planned regardless of bb height) and run the sag slightly less. All together it’s made a big difference.

    paladin
    Full Member

    scotroutes

    A shorter crank raises the CoG again though.

    Only on one side, lowers it on the other side 😁

    chakaping
    Free Member

    My new enduro sled may be a touch too low. Better since I put another spacer in the shock but I reckon an extra 10mm travel on the fork will fix it good and proper.

    geex
    Free Member

    so a whole 3mm higher at the BB?

    If only it were possible to improve visual spacial skills and foot position coordination

    chiefgrooveguru
    Full Member

    “so a whole 3mm higher at the BB?“

    Missing a rock by 3mm is as good as missing it by 300mm!

    geex
    Free Member

    I know which would feel more satisfying if it was a rock I’d thrown at your heid 😉

    RamseyNeil
    Free Member

    change from flat pedals to SPDs and your problems will largely disappear . If you currently use SPDs then ignore my comment .

Viewing 32 posts - 1 through 32 (of 32 total)

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