Is the friction system on a bicycle nesessary?

Are you thinking of always keeping the chain on one of the front sprockets? That would be like converting your 2×5 =10 speed into a 1×5 = 5 speed.
If yes, then there is one disadvantage I can think of. Bike chain is made to bend in one direction – around the sprockets. It has very little capability for lateral movement. Ideally you should use rear sprockets #1, #2, #3 when your front sprocket is on #1 and rear sprockets #3, #4,# 5 when you are on front sprocket #2. That minimizes lateral chain loading. I’m guessing you are not an Olympic athlete nor is your bike built right at the stress limits. So you are ok with only one front sprocket. Just be aware of the lateral loading and try not to spend all your time at the extremes.

@worriedguy Thank you very very much for that answer. I had no idea what that thing did, really.

I’m a total amateur at this stuff.

Adding to what @worriedguy said – choose the front chainring which is closest to in-line with the middle of the rear cogset. That minimizes the left or right deflection when you use rear cogs 1 and 5.

You can eyeball it, the measurement is not critical. Or place a straight-edge against the front chain ring and see where it lands on the back cogs.

If they are about the same, choose the bigger or smaller ring to suit your pedaling preference.

Yes they are. But there are some bikes called “cruisers” that have one gear ratio like back in the old days and are pretty cool if there aren’t many big hills where you ride. Doesn’t get any more plain than that.

Technically you could remove the front derailleur (“friction system”) but as has been pointed out, you will severely limit your gearing options. Personally, I have a 21-speed mountain bike, but never use six of them since that would make my chain flex sideways too far, and there are a few more that are iffy for that reason. In your case, you would be turning your 10-speed into a three-speed.

Given that I have lived most of my life in hilly places, I find it less of a hassle to fix an errant front derailleur or shifter than to find one chainring that will work on level pavement and killer hills. At least you don’t throw mud into the mix… or do you? I could never abide by only having one chainring, or even two; I need three rings and at least six cogs on the rear (18 speeds) since I hit a range of stuff.

But that is me. There are people who swear by “fixies” that have only one gear, no freewheel (the pedals are always moving as long as the wheels are turning) and many have no brakes, relying on the rider’s legs stopping the pedals and therefore the wheels and hopefully the bike. You don’t see them near the hilly parts of town very often and those fixie riders that do hit the hills are in great athletic condition.

So, to answer your question of whether that part is necessary, it depends. What shape are you in? What sort of riding do you do? Over what terrain? Is there a happy medium between your preference for simplicity and your riding needs?

@All Thank you for your input. I know it’s obvious I don’t really know what I’m doing. That’s what the point of this bike is for. I want to learn and you’ve all helped me quite a bit :)

With a little TLC to those derailleurs and chain ,they will be smooth as butter. It is nice to be able to change gears when riding. You can’t really mess up anything by experimenting on which gear ratio to use when. Soon you will figure out your favorite setting and use it more than the rest with a variation up or down from that one. One of mankind’s best inventions.

Correct, @woodcutter, and it doesn’t take much TLC either. I have rarely had to do anything to the front derailleur on any of my bikes beyond the occasional dousing in WD-40 or other spray lube. Maybe the occasional tweak on the cable adjuster to compensate for cable stretch if you have some form of index shifter (friction shifters don’t need that) a couple of times a year. Pretty low maintenance really.

Rear derailleurs are a little more time-consuming since they tend to be used more often and thus fall out of adjustment more frequently. I find myself tweaking the adjuster nuts on my rear shifter (I have grip shifters) about every other month. It takes about five minutes to get perfect. Combine that with the two minutes it takes every 4–6 months to adjust the front and we’re talking…. well, not long at all. I spend far more time lubing.

I find that the most essential skill really is how to true a rim. Sure, you can spend a kajillion dollars on carbon fiber rims that never warp though they occasionally shatter but most people wind up with rims that have adjustable spokes and occasionally get a little warped. This can lead to worn brakes, handling issues (wobbling), and just plain badness. Some people will adjust the rim so it’s straight but not bother making the tensions even so it’ll warp again (probably worse than before) within a few miles. I managed to bend a rim about five inches sideways after something stupid, yet within twenty minutes, I had it nearly laser straight and true, and evenly tensioned to stay that way.
It really isn’t hard to do right if you know a couple simple tricks. The big trick is to just spin the wheel and let the spokes tap your fingernail of something so that they make a sound, not unlike tuning a guitar. Too high a sound meant too much tension and you might pull the nut through the hole in the rim. Too low is too loose; the rim won’t hold shape. If the tone is constant, so is the tension and all is good. If the tone varies, the tensions are uneven and you’ll have issues.
The lesser trick about rims is knowing which spokes to adjust and by how much. Simply put, there isn’t any rim warpage that can be suitably fixed by adjusting only one spoke. It’s hard to describe as it’s really one of those cases where a picture is worth a thousand words.