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So, I recently bought this bike: https://www.decathlon.co.uk/p/road-bike-triban-rc-120-grey/_/R-p-308062

At the front are two cogs, small and large. I did say I was a newbie!!!

At the back are 8 cogs, small to large.

My question is what do I use where? Is there a path from the easiest gear to the hardest gear or is it a lot of swapping and changing?

So let's say I start off on a flat, what should I start with e.g. large front, small back. What if it starts getting steepe? Do I change front or change back? Steeper still, do I change front and back? Likewise if I start going downhill

Any advice would be great

I tried riding on it to get used to it but came off more confused.

Appreciate any help

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In back, the cassette has 8 sprockets ranging from 11 to 34 teeth. 11t is the hardest.

In front, you've got two chainrings, 34t and 50t. 50t is harder. So 50x11 is your hardest gear, 34x34 is your easiest.

It's helpful to think of the chainrings as giving you a high range and low range, and the sprockets in back as setting your exact position within a range. Also, the ranges overlap considerably.

This can help you visualize your gear ratios and shift pattern.

There's no hard and fast rule that you should use this gear in this situation and that gear in that situation. You'll probably find that being in your 50x18 or 50x21 is a comfortable gear for just riding around on the flats. When you approach a stop, downshift two gears in back so you can take off with better acceleration. When you're on a climb and you've worked your way down to the next-to-biggest sprocket in back (aside: why next-to-biggest and not biggest? this avoids a situation called cross-chaining, going big-big or small-small, which is less efficient and not good for the chain), shift down to the 34t chainring in front and shift up two gears in back. Reverse this when you're on a downhill speeding up.

You'll notice on the linked page that the black triangles show the number of teeth in each sprocket, and there's a number above them representing gear inches. This is a way of expressing the mechanical advantage of every ratio; the formula is (chainring teeth ÷ cassette teeth) × wheel diameter. So you can see that from 50x28, with 48.1 gear inches, the next gear down is 34x21, with 43.6 gear inches.

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    Concur. Start by ignoring the front chainrings and left shifter. Just use the right hand shifter and rear cassette to begin with, That may help simplify the gearing.
    – Criggie
    Oct 11, 2022 at 20:38

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