First ride on the new bike...

[ufkacbln]

A bike like this is simply a marketing person's idea of what cyclists will buy

A "real cyclists" we know that this will be a series of compromises and fudges

It is simply an empty canvas awaiting your additions to make it into a masterpiece!

 

[Pat "5mph"]

@John the Canuck hit it on the nail regarding the sliding down from the saddle.
I had the same on my first hybrid, actually searched on here for a solution, the spirit level on the saddle answer came up, problem solved
About the brake, I know what you mean, having a bike with disk brakes now.
If the v-brakes are set up correctly (no touching the tyre, wheel properly in drop outs) the "juddery" feeling you get is because you're not a smooth front brake operator
I also find that when my rims are too clean smooth front braking with vs takes more of an effort.

 

[TheJDog]

Front Brake, make sure the front of the pads touch the rim 0.5 - 1mm before the back.

By which he means the front of the pad towards the back of the bike. This way you get a water clearing effect when it's wet, too.

 

[Globalti]

Where does the front brake cable attach to the bike? Can you post a photo? If the mount is high up and there's a lot of bare cable it could be that you are suffering the classic cyclocross bike brake judder problem. Distortion in the forks under braking causes the bake to release, which allows the fork to spring back, causing the brake to grab again, distort, and so on in an endless cycle of juddering. There are ways of curing this but we need a picture or at least a link to a manufacturer's pic of the bike.

 

[Brandane]

Where does the front brake cable attach to the bike? Can you post a photo? If the mount is high up and there's a lot of bare cable it could be that you are suffering the classic cyclocross bike brake judder problem. Distortion in the forks under braking causes the bake to release, which allows the fork to spring back, causing the brake to grab again, distort, and so on in an endless cycle of juddering. There are ways of curing this but we need a picture or at least a link to a manufacturer's pic of the bike.

A fellow Tricross owner, IIRC?!
Mine was not bad from new; I think my version (2010 model) was improved by the fitting of a cable guide bracket at the top of the fork. Further improvement was made by fitting Koolstop dual compound pads.
@ScotiaLass , my top tip for adjusting the "toe-in" setting as suggested by @cosmicbike - loosen off brake shoe then place a 5p coin between rim and the rearmost part of the pad, while lining pad up with the rim. Pull the brake lever to keep it all in place while tightening the shoe/pad in position. The coin will ensure the rear of the pad is about 1mm further from the rim than the front end. An assistant can be handy for this unless you have 3 hands!
Personally I have always found the toe-in solution a bit hit and miss. Koolstop pads (salmons or dual compound, NOT the black ones!) on the other hand have been more successful at curing judder, squealing, and improving brake performance.

 

[KneesUp]

If it continues to give you back pain, you could swap the stem for a longer one thus making the saddle to handlebar measurement a bit longer?