Advice on which gear to use

I Don't know exactly how to phrase this question but here goes: Is it better when training alone to stick to the smaller front blade and just shift the rear derailure in order to keep cadence up and heart rate lower (and easir on the legs) and just shift to the higher range when riding in a group where the speeds are higher? I have found that in the higher gears I struggle to keep the cadence up and the heart rate down. There is about a 2km/h difference in speed (higher gear faster).
Now 2km/h over 100km makes a huge difference, but riding a higher gear could make you more tired than riding a lighter gear.
So which gears do you guys use?

Sounds like you're pretty new to cycling. Excuse my presumption if you're a cycling vet.

Anyway, it's not a hard-fast rule (old school guys may disagree) that you stay in the small ring when training alone or during the non-racing season - it's all about gearing, regardless if you're in the big or small plate. You shift to the big ring when the speed, and/or your level of cardiovascular fatigue dictates that you spin a lower cadence. The reason your heart rate goes up is due primarily to the higher wattage required to travel at higher speeds, and to a lesser degree the higher rpm that may accompany the higher power/speed.

When training I'll use a multitude of gears (big and small ring) - basically I'll try to replicate the power requirements and cadences for the durations I'll see during an actual race scenario. A power meter facilitates greatly this training aspect.

Keep riding your bike and you'll soon enough find out what you're body is most comfortable with in terms of speed, cadence, and perceived exertion.

Good advice.

As someone who comes from the “old school” – let me impart what I have learned over the years.

In my early days in the sport my old coaches used to use “the method” system of training.
Basically this meant putting the bike in to one gear ratio for an entire training schedule and trying to maintain
a fixed cadence within that gear ratio.
So for example, we would select 42x17 and pedal continually at say, 90rpm, for an entire training session.

The idea behind this being that one builds strength and pedalling fluidity using that one gear, at a given cadence.

As a newbie, a person should select a gear to pedal in which is not too difficult for them to turn, but one in which they
can also maintain a relatively high cadence.
As their strength improves, they should then progress on to the successive heavier gears while attempting to keep a high
cadence – and progress thus.

Of course, my introduction to the sport was in the days well before heart monitors, power meters etc.
We had to rely more on readings like resting heart beat measurements, lactic acid buildup: basically listening to your body.

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morelike hypocrisy.

if you just pick the gear regardless of speed.. that give you a cadence of about 90-100 +/- rpms you should be fine.. so if you're going faster you'll need a bigger gear smaller cog at the back and i may or may not require you to switch to the big ring at the front... smaller gear when you go slower is the opposite..

you'll be able to go faster with same or less effort in some situations... e.g. downhill, in a group behind other riders, with the wind at your back etc... you'll need a bigger gear in those situations

you'll go slower in some situations.. uphill, with wind in your face, riding solo as opposed to in a group behind other riders etc.. you'll need a small gear in these cases...

also you need to consider that in the small ring and big ring at the front you'll have gear combos that overlap and will feel the same and result in the same cadence at the same speed... pick the combos that give the best 'chain line' so if you're in the big ring try not to use the biggest three cogs in the back and if you're in the small ring try not to use the three smallest cogs in the back.. if it's just for a small length of time it's fine but not for extended periods of time.. these combinations cause the most friction from the drive system

Gearing is simply a means to an end. Having lots of gears allows you to more easily keep within your desired pedaling cadence range. One you have found your idea pedaling cadence (how fast you pedal) for a given situation, you simply adjust the gears with respect to the speed you're riding at.

As for training you'll want to go by effort. You'll need to figure out approximately how hard you need to go during a training session and then, based upon how fast you are riding, you'll select a gear to suit.

Don't think of it as "what gear do I need to train in" think of is as "I am going this hard and therefore this fast, let me change gear to suit this effort" Once you get your head around that, 80 years of cycling myth and fokelore goes right out of the window and winters become much more productive...

As already stated, it's typical to ride ~90rpm on the flat, a bit slower into headwinds and on climbs and somewhat faster on downhills and sprints.

Thanks for the advice, since posting I have tried out keeping a constant cadence of about 80-90. At this cadence I am most comfortable, any faster and I lose form and start bouncing up and down. So I can then safely say the gearing is not that important, keeping up your cadence and determining your intensity for the session is what matters.

You should be able to spin faster- see books and other threads - "bouncing" indicates low saddle height/poor position or unequal leg length, see a good shop, coach,read and work on it more
(MY legs are 2cm different and I have a 1 cm shim under my right cleat)

I think it would depend upon whether you have decided what kind of racing you are going to do. If you are going to do triathlons or concentrate on cycling time-trials then you should concentrate on getting comfortable pushing big gears and keeping the cadence low. If you want to do track racing or cycling road racing then you also need to learn how to be comfortable with higher cadence riding also. whatever you decide to do it will eventually come with more and more time in the saddle.

Bouncing can also indicate poor technique.

Also, if you have a 2 cm leg length difference you would probably be better off with two different crank lengths rather than a shim to try to compensate for this.