Hello.
I am 14.5 years old, weighing 60 kg (135 lbs) and I am currently using my electric bikes for my commutes, which are from 4-7 km long rides, a total of typically 15-20 km a day.
I wanted to switch to bike without a motor, and I have a few questions:

1. I dont want to get sweaty, since I'd be riding to school. I can I do that?
2. I do a lot of sports, including 6 hours of surfing in some days. does the cycling take a lot of energy?
3. What type of bike should I buy, considering mostly road and sidewalk terrain, and how much should I invest and how would it make difference ?

Thanks a lot!

1. How sweaty you would get depends on how warm it is and how hard you're working. Riding slower means you would sweat less but if it's hot out, you have a long way to ride or you have big hills to climb you might get sweaty even if you're riding relatively slowly.

2. This is related to #1 . Generally you work as hard as you want to, but long steep hills are going to be hard regardless. The distances you mention don't seem too bad. If you're athletic I don't think you'd find riding a bike to be very hard, especially after you got used to it.

3. If the roads are smooth you have lots of options but it still depends on how much you want/need to carry with you and again, hills. A lot is just personal preference, especially when it comes to shorter distances. You don't mention whether you male or female. The only reason I mention that is a 14.5 year old girl may not get a lot taller where a 14.5 boy still has some growing to do. I wouldn't spend a ton of money on a bike that may not fit you in 2 years.

By the way, I've seen people in Hawaii ride with surfboards mounted to their bikes.

Thank you.
As for 1, I really want to hit the high speeds, but I guess my ride for school is only 3 km so I can relatively ride fast without getting sweaty.
3. I would like to carry with me a lock, a backpack and sometimes a surfboard, which I mount on the bike
I am a male, so how much should I invest on my bike, assuming a budget of around 800$ for a second hand bike?

To be honest I'm a little hesitant to recommend a particular dollar amount. I don't know what your financial situation is and what other things you may want to save your money for. $800 would seem like more than enough and I'd be inclined to spend less since the bike make only last you a few years before you outgrow it. I'm also not sure what's available in your area for second hand bikes.

For reference though my son needed a new bike when he was about a year younger than you. We said we would pay for half. It was up to him to save the rest. He ended up getting a new fixed gear bike for about $300 (USD). For a new fixed gear bike, I wouldn't have wanted him to spend much less. I think that's around the minimum (give or take $50) for a decent quality fixie.

That kind of bike may or may not make sense for you. We live in an area that's pretty flat and he never carries more than a backpack with him. He's 15 now and I expect he'll get at least another year out of it before he outgrows it.

I would find somebody local who knows about bikes before buying something 2nd hand and as far as how much to spend, I'd consult a parent/trusted relative who knows a little more about your financial situation.

I should also make it clear that I don't want you to share your financial situation on this forum. I'd definitely want my teenage son to be very careful about what sort of information he was posting about himself.

To get an idea of what kind of bikes other people have used for what you have in mind, go to google images and search for "surfboard on a bike". You'll see some expensive fat tire bikes and some cheap cruisers. All would probably get the job done for you. Fatter tires with some tread are going to work better in the sand but will slow you down a bit on the street.

most any bike would do for those short routes. A mountain bike with slick tires might be the best. I just got a cheap single speed for my commute, and it works best for me, but what works for me may not work for you.

Basic recommendations: By from a bike store. The will be able to size the bike for you (which is critical), sell you something that won't fall apart in a couple of months, and often offer free service or good discounts on service to keep the bike running well. Besides, name brands have good resale value on craigs list.

That's a really short ride. You will get sweaty on hot summer days (>75F), but a change of clothes and some deodorant will handle that.

A backpack is going to make your back sweaty no matter what. I'd lean towards a rear rack and panniers instead.

Don't worry about energy levels. Biking is the most efficient human-powered transport, and I'm sure your legs are strong enough from surfing to absorb a short ride.

If you're riding to the beach, you may want to look at hybrids or even mountain bikes. Sand and road bike tires don't mix well.

You can control the amount of energy cycling takes yourself by setting your pace accordingly.

I don't mind getting sweaty as I ride. I dry off a while after I arrive. The more you sweat, the more you get used to it.

By the way, where are you? Canada, Europe, somewhere else?

Thank you all very much! I wanted to see what is the price where bikes don't get significantly better.
I wont be exactly driving in the sand, but the road may have really small amount of sand on it.

I am from Israel, and it can get quite hot in here.