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Whilst I'm making myself look dense...

Discussion in 'Beginners' started by Cathryn, 13 Nov 2007.

  1. Cathryn

    Cathryn California Correspondant

    ...to run alongside my muppet puncture thread, I have a chain question.

    We had a bike mechanic on our India trip, who took great delight in cycling alongside me and telling me I was in the wrong pair of gears (big and big etc). He seemed to think I should be able to look down and see if I was in the middle cog both at the front and the back.

    First of all, should I be aiming to have the chain in the middle cog at the front whenever I'm not going uphill or downhill?

    Secondly, how on EARTH can I tell what cog I'm in on the back derailleur? I nearly hit a sacred cow trying to check, I just can't see it whilst I'm cycling.

    Finally...can someone talk me through this chain and cog malarky? I've always just gaily sat in whichever gear I found most comfortable - it was a shock to find there's a science about it and I have no idea what to do.

    Thank you!
     
  2. I think the general idea is to keep the chain in as straight a line as possible Cathryn...
     
  3. OP
    OP
    Cathryn

    Cathryn California Correspondant

    Even if that means cycling in a gear that's not as resistant as you'd like? And is there a trick to checking my back derailler whilst cycling?

    Sorry to be thick, I know this is a ridiculously girly question but I honestly am flummoxed.
     
  4. Zoiders

    Zoiders New Member

    Location:
    Ice Station Zebra
    Get some more miles in

    Use lots of different ratios, go across the whole range

    After a while you get a feel for the gears, the cadance and resistance from the different rings and sprockets

    You will be able to tell with out looking
     
  5. Fab Foodie

    Fab Foodie hanging-on in quiet desperation ...

    Aperatif is correct.
    Assume you have a triple chainset (3 cogs at the front).
    In the middle gear at the front you should be able to use all of the rear cogs without problem, but occasionally at extreme ends of the rear cogset the chain may just rub the front mech, not always but may.
    I probably spend most of my pootling time in the middle ring/gear and ride the bike like a nine-speed.
    What your Indian chap said is correct...if you're running the granny gear (small front ring) you should try only to run the bigger 7 of the rear cogs, this is to keep the chain reasonably straight. The same is true when you are on the biggest ring at the front, you should try only to run the smallest 7 rear cogs, again to keep the chainline fairly straight.
    If you have Big front and Big Rear (ooeeerr missus) you will see that the chain is running at quite an angle, this will quickly wear chain and cogs, likewise, little front and little rear.

    On a 21 gear bike there are duplicates of gears and those gears that you cannot run as (described). The trick is to learn a shifting pattern that allows you to go from lowest gear to highest gear in nice easy steps without chain-line issues or double shifting.
    Also find which gears are comfortable for everyday use...I found that in London I used 1 gear about 90% of the time...so I went fixed and used the same 42/15 gear ratio.
    Often bike reviews (such as C+) have a gear-guide printed, a table which gives gear "Size" in Inches (see Sheldon for explaination!) With this you can see which gear combinations a bike has. Sheldon site has a calculator for gear size. Top gear on a road bike could be 110 inches and bottom gear on a tourer as low as 27 inches which is almost a 1:1 ratio, ie 1 turn of the pedals creates 1 turn of the wheel. Top gear is around 1 pedal turn giving between 3 and 4 turns of the wheel. My fixed gear is around 73 inches or about 2 turns of the rear wheel for 1 turn of the pedals.
    With a bit of practice and the odd glance at the rear cogs, you get used to which gear combinations work for you and which don't.
     
  6. ash68

    ash68 New Member

    Location:
    northumberland
    AS aperitif says, in general try not to use the big chainring and little sprocket, or the little chainring and biggest sprocket as this causes alot of wear on the chain.The chain will be running at quite an angle if you use these combinations and also chain rub is likely on the front mech.Other than that use the gears you feel most comfortable with. It's your bike, ride it how you so desire and just grin and nod your head at anyone who tells you otherwise:smile:
     
  7. littlered

    littlered New Member

    You will just know what gear you are in I'm usually in the middle cog at the front and 5th at the back:smile:
     
  8. you where 1/2 right the big don'ts are ( big and big, small and small )

    have a look at http://sheldonbrown.com/gears.html there is some good info ie: (pushing v spinning)
     
  9. fossyant

    fossyant Ride It Like You Stole It!

    Location:
    South Manchester
    As said, it's about the chain line - i.e. outside biggest chain ring and inside biggest sprocket is a no-no.... and vis versa......too much bend on the chain... With many bikes there is a massive overlap of gears anyway - I run a fairly straight through block (i.e. 1 tooth increment 13-19 plus a 21 on my road bike 8 speed) as I get the best small gear increments.
     
  10. OP
    OP
    Cathryn

    Cathryn California Correspondant

    Thank you for some very kind and non-patronising answers. Am very grateful. Off to look at the bike. I'm guessing it takes practise!
     
  11. OP
    OP
    Cathryn

    Cathryn California Correspondant

    Sheldon. What a guy. Fab.

    Light is starting to dawn!!
     
  12. frog

    frog Guest

    here's my two pennyworth - feel free to shoot it down at your leasure :blush:

    Think of the rear cluster as divided into three. If you have 8 then think of 1,2,and 3 as the 'low' group. 4, 5, and 6 as the 'middle' group. 6, 7, 8 as the 'high' group. Biggest cog is 1 and 8 is the smallest. On the front end the little ring looks after the low group, middle the . . etc.

    The idea is to keep the chain straight so if you want a low gear for a steep hill you change down to the low group on the back and the small ring. If you want to go faster then change up using the rear cogs only. This will take you happily up to 4 on the back and then the chain will start rubbing on the middle chain ring. At that point you'll need to move onto the middle ring and, to keep the work load down, drop a gear on the back. Same applies to the next ring as well.

    Now you're belting along in 8 on the back and the large chain ring. A rapid change down is done on the front ring, to the middle and cog 7 on the back. From here you can drop the gears in pairs because a big push on the lever will move two gears instead of just one. Two big pushes will get you into 3 and there you can either stay with that or go to the inner ring. Clear as mud ain't it.

    Knowing what gear you#re in comes with experience. For me it was a quick look down at my feet which showed me what ring I was on and if I had the balamce or time I could look back and get an idea which cog as well. If I didn't have time I'd just check if the chain was running either to the left or the right. If it was to the left then my next change up would be onto a smaller cog, a change down would mean a smaller ring and visa versa for it pointint to the right.

    However, you can throw all this out of the window and get yourself a bike with hub gears :tongue:
     
  13. if it's a 7 speed block you should name each sprocket after a day of the week and the three chainrings after the muses.

    of course, with 8 and higher blocks this becomes difficult, so you have to make up names of the week - and these sometimes don't correspond to other people and bike reference books. double chainsets also are missing a muse.

    hope this helps
     
  14. OP
    OP
    Cathryn

    Cathryn California Correspondant

    I'm going to have to head out at the weekend for a daylight ride. What I seem to be getting is that if poss I should be in the middle ring in the front and look down to see how straight the chain is.

    Aaaagh...this is a whole new world.
     
  15. Smokin Joe

    Smokin Joe Legendary Member

    Provided the chain doesn't rub on the outer ring or the front mech I doubt if running off line makes much difference to chain life. They are flexible devices and the amount of bend is hardly noticable over the full length, even with short rear stays. I regularly use eight of my ten sprockets from the small ring and the ninth now and again with a bit of trim on the front mech, the things still seem to last as long as they always did.