Mountain bike style hybrid or mountain bike?

[Lucycw]

Hi all, I'm new here and am trying to make a decision about a new bike! I've been riding a women's Decathlon RockRider 5.0 and am now looking to upgrade. The type of riding I do is really a 50% split of trails along the river and road. The trail along the river is a mix of gravel/dodgy tarmac/muddy grass/mud and in some places are very bumpy and I really feel them on my Rockrider. I haven't done any specific mountain bike trails because I'm not very confident but we live pretty much next door to Swinley Forest so there's a possibility that I may work up the courage to have a go in the future! I would say my preference is riding off road but only marginally - I'm pretty happy with both. Also, I'm doing the Palace to Palace bike ride in October which is all on road.

So that brings me to my question - hybrid or mountain bike? I've been looking at hybrids at the sporty end because the trails I ride on would be too much for a road type hybrid. So I've looked at the Specialized Ariel Sport Disc - http://www.evanscycles.com/products...sc-step-thru-2014-womens-hybrid-bike-ec041318 and recently was shown the Marin San Anselmo - http://www.marinbikes.com/gb/bikes/description/2014-san-anselmo-ds3 which to be honest I probably prefer to the Specialized just going by feel/comfort alone. The sales guy informed me that the only difference between these and a mountain bike is the wheels will be better on the road. Is this right or are there other differences?
Would I be right to buy a hybrid of this style or am I better buying a mountain bike and then potentially putting a tyre on that's more road friendly? To be honest, I need all the help I can get keeping up with my boyfriend, particularly on the hills (though this has improved as I've cycled more)! Any recommendations on a bike to suit my riding? Ideally I'm looking at the £500-600 mark and can get vouchers from work to buy at Evans or Halfords at 10% off, though I'm willing to buy from anywhere for the right bike.

 

[raleighnut]

Avoid suspension for climbing on roads, other than that its just down to wheel size so just go for what you feel comfy with, tyres can be had for either size/style and in lots of widths. Fatter-comfy Thinner -faster and most are tough enough for off road usage.

 

[KneesUp]

My two pen'eth is not to get too hung up on descriptions. Either of those bikes will cope perfectly well with the trails. I ride a 1990 MTB which was considered quite good when it was new, but isn't so different from your Rockrider 5.0 - no suspension, 21 gears, nice solid frame. It was good enough to ride off road in 1990, so it's good enough now. Unless you are very powerful or racing, the bikes you have listed will cope perfectly well with the uses you propose. A full MTB will be tougher, but for most people riding off-road I'd imagine that they will be tougher than they need to be.

Equally a good MTB will be fine on road. I used to commute along almost the same route as a friend when we were both young and fit. He on his steel Bontrager MTB with flat bars and road slicks, me on my Reynolds road bike with drop bars - and there really wasn't much in it over 5 miles, and I'm not sure there would have been too much in it if we'd gone further - the same friend used to enjoy tagging along (and keeping pace with) the training runs of the local cycling clubs on their mountain bikes. It's the rider that makes the big difference.

For hills you want to be taking as little weight as possible, which would be another point in favour of the hybrid.

 

[Lucycw]

Thank you for your help! I think I'll go for the Marin then and focus on improving my own riding. I'm already making an effort to practice on climbs near me and am seeing an improvement!