New bike gearing

Boardmanboy
Boardmanboy Posts: 24
edited April 2012 in MTB beginners
Please help! Ive just bought a Boardman Urban Mountain Bike Team for mainly fitness and I would prefer the gearing to allow more top speed, I just dont need the second chainring! Ive been told that the FSA Comet compact crank 42/27 is maxed out and a larger chainring is not available :(
At the rear is a 11-34-tooth 10-speed cassette and the BB is a FSA Mega Exo Bb-7000.

Assuming 11 tooth is the smallest you can go at the rear, am I right in thinking I need to change the whole crankset? What would fit? Would I also need to change the bottom bracket?
I know a road bike would've had the right gearing already but I wanted something with disc brakes and tougher wheels for the kerbs in my area!

Comments

  • omegas
    omegas Posts: 970
    42 front 11 rear 100 cadence will give you a speed of 32.7 mph , how fast do you want to go :lol:
  • vanamees
    vanamees Posts: 75
    Bigger chain ring will help if you can ride current gearing ca 50kmh average.
  • The Rookie
    The Rookie Posts: 27,812
    Measure the dimensions of the bolts holiding the outer ring on, I think the FSA ar 104mm/4arm in which case 44T rings are readily available, in fact I have one for sale!

    I regularily hit 26mph on my 32T ring double, so 42 would see you hitting 34mph+, as asked, how fast do you want to go?

    Simon
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • cooldad
    cooldad Posts: 32,599
    Ride gnarrlier stuff and it'll be more than enough speed.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

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  • Hmmm I've not been cycling for many years till last week; I can only manage 60 cadence which seems to give me around 20mph. And that feels like im pedalling far too fast - faster than I see anyone else riding lol, I know with 'an extra couple of gears' I could go much faster without the stupid rpm.
    @The Beginner there are only 3 bolts holding the chainring :(
  • supersonic
    supersonic Posts: 82,708
    I'd see if you can manage more cadence - most people are most efficient in the 80-100 range, 60 actually wastes energy.
  • Can someone clarify for me, one cadence is one full revolution of the crank? So if I count how many revs during one minute then this is my cadence?
  • supersonic
    supersonic Posts: 82,708
    Yep, RPM of the cranks!
  • Ok, thanks. So what is what I really need to do is just keep at it till I can increase my cadence rather than increase the gearing? I'm wondering now that when I'm cycling at over 60 rpm, it feels too fast because im not able to do this smoothly. Maybe I see other riders actually doing more rpm but it looks 'normal' because they are smooth and not jerking all over the place like me lol?
  • supersonic
    supersonic Posts: 82,708
    Make sure the saddle is at the right height, and try and turn the pedals in circles.
  • Ive just been reading that SPD pedals may help - you can lift up as well as push down. Are they worth it?
  • supersonic
    supersonic Posts: 82,708
    They can help some people, but it is a technique worth learning on flat pedals. You don't really pull up, more unweight the pedals, and push them in circles. You don't need SPDs for this.
  • Sorry, I don't really understand that. How else can you pedal - surely the only way is to go in circles?!
  • Ah, do you mean instead of just downwards pressure?
  • supersonic
    supersonic Posts: 82,708
    Lol, yes, don't mash them up and down, try and spin smoothly.
  • cooldad
    cooldad Posts: 32,599
    If you can't manage a higher cadence you are in too high a gear.

    The pedals can only turn in a circle, obviously, but a lot of people only push down on the pedals (and get power on for maybe 60 or 70 degrees*), not round using ankles etc as well. You'll know if you feel it.

    *I made this up.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • Yep that makes sense, not sure if I do it anyway but I'll make a conscious effort tomorrow. So if I change down a gear or two to attain a higher cadence I will obviously end up going slower, but what else will this achieve?
  • supersonic
    supersonic Posts: 82,708
    If you change down a gear, and up your pedalling to reflect the change, you'll be at the same speed ;-)

    Try and use the gears to stay at a high cadence.
  • Right I'll try it out for a while. Cheers
  • cooldad
    cooldad Posts: 32,599
    Doesn't really apply to actual trail riding, where you're riding up, down and round about, but the technique with any endurance sport like running or cycling is to get your own cadence, and stick with it, using the gears to maintain it.
    So obviously you will go faster on flat or downhill, but the cadence will stay the same.
    Also applies to running, keep the cadence but vary the stride, so long strides down hill, shorter uphill but same number of steps/time.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • Ok quick update - I got and Edge 800 computer and can now measure things accurately. My average cadence seems to be around 68 on a 30 mile ride, topping out at about 120 when really going for it which equates to 32mph. To be honest it seems to be pretty rare in the real world when I'd reach that and I now know, thanks to the help on the forum (thank you) that this gearing is adequate for my needs (till I give in to buying a REAL road bike lol).
    I actually replaced the tyres with Continental UltraGator Skin Rigid Road Tyre - 26 x 1.125 Inch (28-559) and what a massive difference that has made! Along with SPD's and proper cycle clothing lol, just need some socks for the 4degreesC evenings we're having around here:)
  • YeehaaMcgee
    YeehaaMcgee Posts: 5,740
    Also worth thinking about is that, it's a mountain bike. Maybe you should have got a roadie if you're running out of gears on cycle paths.
  • cooldad
    cooldad Posts: 32,599
    +1 veeted potato
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • The Rookie
    The Rookie Posts: 27,812
    68 is a bit slow, ideally you should be spinning at about 90rpm, and unless your running out of gears still at 90mph at max speed.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • cooldad
    cooldad Posts: 32,599
    68 is a bit slow, ideally you should be spinning at about 90rpm, and unless your running out of gears still at 90mph at max speed.
    90mph? You are my hero.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools