As redbike says avoid Mechanical Disk brakes, V-brakes are better if set up correctly. But if you want to ride through the winter good discs make a difference. Before I had discs I finished many a winter ride walking downhill as my brake pads had disappeared!
I have the 4300 with v's, and although the stopping power is actually very good, I wish I had gone for discs...at the time I thought I could just upgrade and go straight to hydraulics, but completely forgot that the hubs are not disc ready and that all the shifters would need changing as the current ones are combined brake/gear shifters, so it's not really worth it for a bike at that price...
AFAIC it's worth spending the extra money, even if the discs you get are only mechanical - then again, I suppose it depends what you want to use the bike for...
PS it's a great little bike, I love mine to bits - he's just had a new fork for christmas, really good ride!
I agree with punky, not all mech disc brakes are poor- the avid range is generally regarded quite well, and I've had Shimano mech disc brakes that are effective. They just need more adjusting than hydro systems as they usually only have one moving pad. The main reason for agreeing tho' is the ease of upgrading, as you already have disc hubs and wont need to upgrade the wheels straight away and may well find that the mech brakes suit you just fine.
Thank you everyone for the helpful hints and ideas.I have been from Staffs to Los Angeles reading the reviews in mountain bike threads.A decision has been made i will go for 4300 with v brakes £300.This bike will be used mainly on tow paths and local paths around waterways.Never intended to go serious mtb.To answer Bonji i wish to extend my leg it felt as though i was putting too much pressure on the knees,something i wish to avoid after having two ops one one knee already.Now just have to get the money out of the household budget.
Single pot hydraulic
Double pot ( or more ) hydraulic.
Mechanical ones usethe same brake cable that a V-brake would use. Generally cheaper and performance generally on a par with a good set of V-brakes. You can get more advanced ones whose power is better than V's, but at that price for them, you start to enter entry level hydraulic prices. Generally, with a mechanical you generally have 1 pad side that moves under cable pull, and the other pad side static. the static side pad ( normally the spoke side ) can have its distance from the disc adjusted by means of an allen key, so you need to run it quite close to the disc ( which can cause scuffing ) . The moving side then gets pushed against the disc, and then against the static pad to clamp. This slightly bends the disc as it does so and I found that in some cases this lead to uneven wear of the pads ( a little like toeing in brake pads would cause uneven wear ) and that you did need to fettle with the distance to get it right. The upside of mechanica discs is that they are simple and cheap.
Single Pot Hydraulic.
Basically the same as mechanical really. the hydraulics move only one side the pads and the other remains static. Power will be better than that of mechanical V's, but you still have the issue of slightly bending the disc. One of the most common used to be Hayes 'Solo' 9's
Dual Pot ( or more ) hydraulic.
These are the real deal. Instead of 1 moving side and 1 static side, you have a caliper piston on both sides pushing both pads against the disc in an even manner. This means that the pads clamp the disc without bending it and equal force and wear on each side. There are a ton of different versions from the various manufacturers and its a hugely debated topic. Even the base model versions from the likes of Shimano nowadays are outstanding compared to V-brakes ( personally speaking from experience ) .
Each make also tends to have a slightly different feel to the way the brakes work as well. Generally I found that Hayes brakes have quite an ON/OFF feel to them. The power ramps up really sharply as you pull on the levers. At the other end of the scale, Hope brakes in comparison have a softer feel to the them where you need to pull the lever a longer distance ( not necessarily harder pull, just longer travel ) to get the same power of braking. This is good when your wanting to feather the brakes and kill speed in a variable controlled manner as opposed to an all out stop. Inbetween those is Shimano. Not as harsh as Hayes, but not as mushy as Hopes. ( dont get me wrong about hope though .... pull that lever and the anchors are well and truly on )
You've already decided, but I'd suggest, that it may be worth waiting and buying an aftermarket upgrade to disc brakes. PLaces like CRC and the like often do deals on full hydraulic systems ( dual pot calipers ) and these are likely to be a better long term fit.
Errr, no. Definately not a gimmick, the cable ones on cheap supermarket bikes maybe..... But I really wouldn't fancy riding the trails without my disc brakes now. The power, reliability and mostly maintenance free issues also help! I've had discs pinging while they cooled down, and steam coming off them when wet. There is nothing wrong with Vee brakes when set up well, but they are not a match for disc brakes.
I will agree that the very cheap mechanical discs are gimmicky.
However, I don't agree that discs in general are just for weekenders. On wet muddy trails discs are significantly better. Definitely not a gimmick and definitely worth while. Having got used to the power and modulation of high end hydraulic discs I certainly wont be switching back to V's in a hurry.
I suppose quite a bit depends on where you're riding. On a dry ride along a family trail / canal side then you probably wont notice any advantages over V's. But if you're riding down a steep muddy trail thats so wet it looks like a river then discs are worth every penny.
Hydraulic discs are definitely better, but I did manage to MTB for 10 years or so with V brakes/ cantis. I don't think they should be your first priority on a cheaper MTB - focus on the frame and wheels as they will have more effect on how it rides.