MTB Groupsets

Most bottom brackets make knocking or clicking noises when the start to get towards the end of their life. If there is play / movement in the cranks (push the crank inwards towards the frame) and there is no more pre-load adjustment then it is time to replace.To get the best performance and lifespan from your bottom bracket don't over tighten the pre-load adjuster - this puts extra  load on their bearings and will cause wear quicker, the pre-load adjuster should be just tight enough to eliminate play / movement.

This is much discussed! There are good and bad points for both 1x and 2x systems. 1x is simpler, usually a little lighter, there is no gear overlap, and it is very easy to get used to. 1x drivetrains are proving very popular, most bikes are now 1x and it is fast becoming the ‘norm’. The downsides are the gaps between sprockets can sometimes be felt, particularly on climbs, rear cassettes are also heavier because they incorporate bigger sprockets (however this is offset with no front derailleur, shifter and chainring reducing weight). 2x offers more gear choices, however changing between front chainrings can be tricky in very muddy conditions and 2x is heavier and adds to maintenance.

This really depends on what type of riding you are planning on doing. For most cross country / general mountain bike riders, somewhere between 100 – 120mm suspension is fine for the majority of riding.If you are hitting jumps hard and taking on more challenging terrain,140mm plus will help smooth things out.

We have written a mountain bike size guide which is packed with useful information and tips on sizing.

Read our Ultimate Mountain Bike Size Guide here.

Yes and no. Because the hydraulic brake is a closed system, once they are set up, they should not require much servicing at all. If you regularly use the brakes in filthy weather or in deep mud, braking could wear rotors prematurely because of the mud and grit on the pads grinding into the rotor.

Yes. Manufacturers have made fitting pedals relatively straight forward. Pedal threads are 9/16" 20TPI, this is the standard. There are a couple of things worth remembering fitting pedals; Firstly the left (non drive-side) pedal has a reverse thread (It screws in the opposite way to regular screw threads. Secondly, add a dab of grease onto the crank or pedal thread before screwing in. Removing un greased pedals from cranks can be very, very difficult. 

Yes. Providing stock is available, you can select options such as crank length, cassette ratio, bottom bracket type and derailleur cage length, this allows a good level of customisation for your new build.

Yes, it is more cost effective to buy a full groupset rather than individual components. Buying a groupset from Merlin allows component options too (providing stock is available), so it is also easier to get exactly what you would like.

This is a largely personal choice on which most bike riders have an opinion. Different manufacturers provide their own options for all types of bike riding, each manufacturer has their own particular slant on each component and the technology of how they integrate together. While some riders prefer the solid clunk of Campagnolo, others prefer the cutting edge technology of Sram Wifi or the smooth, effortless performance of Shimano. Campagnolo supplied the winning (disc brake) groupset for the 2021 TDF winner, Tadej Pogacar (UAE Team), recent Shimano and Sram wins suggest that at the top end of road racing at least, there isn't too much to choose between manfacturers.

This depends on how long your legs are, typically taller people have longer legs. Smaller riders would be better suited to shorter 165 - 170mm cranks, average size riders usually go for 172.5 - 175mm and larger riders usually choose 175 - 180mm. Cranks are available in 2.5mm increments from 165mm to 180mm although some sizes can be more difficult to find, especially at the shorter and longer extremes..

It is usually cheaper to buy a full bike because the manufacturer has the economies of scale purchasing components, and they can usually do this more cost effectively than the individual. However! If you want a specific build that the manufacturer doesn’t offer or if you want to use your existing wheels or components you have sitting collecting dust in the garage, it may well be cheaper to build your own.

This depends on the groupset and the chainset. The big groupset manufacturers recommend using all their components in a groupset, however some smaller manufacturers such as Hope, Rotor and DMR make chainsets which integrate with various different groupsets.

No. Bottom bracket shells in framesets vary hugely, depending on your bike / frameset manufacturer. They vary in both diameter, width and also in how they fit the frameset. Some are threaded (Italian or BSA British Thread) and some are pressfit. The best way to ensure a new bottom bracket will fit, is to look at your bike's existing bottom bracket and try to match. Check online for fit and compatibility if you are still unsure.

This depends on a lot of factors. If you ride only in dry weather, using a wide range of gears, your chain and cassette are kept clean & lubed (replace the chain when it gets worn), you could easily see over 10'000 miles on a road bike cassette. At the other extreme if you ride in wet, gloopy, muddy conditions, only use a few sprockets and never clean & lube, you could chew through a cassette in very little time at all. Most riders fall between these two extremes, keeping your bike's cassette and chain clean and lubricated is the best way to ensure a longer life, particularly if you ride a lot off road.

We always recommend following manufacturers instructions for fitting any component. The Youtube channels of Park Tools and GCN Tech have very indepth and comprehensive advice for completing all sorts of jobs on bikes, these are also worth watching particularly if you are inexperienced or unsure.

No. Chains vary depending on how many speeds (sprockets) the chain is manufactured to be used with. 8 speed chains, for example, are much wider than 11 speed chains, this is because the gaps between the sprockets on an 11 speed cassette are much smaller than those on an 8 speed cassette. Most manufactures recommend using their own cassettes and chains together, however specialist manufacturers such as KMC and Wippermann produce very high quality, long lasting chains.

If you are replacing a like-for-like chainring, choosing the chainring should be relatively straight-forward. If you are aiming to match chainrings for a specific crank, chainrings have a couple of things to consider. Firsly the number of 'arms' on the right hand crank arm usually 5 or 4. The bolt circle diameter (BCD) is the measurement of a circle diameter which passes through the centre of all 4 or 5 bolt holes. If you are unsure google your bike's crank BCD.

The number of teeth on the chainring also needs a little thinking about, particularly if you are running 1X transmission.