I have a Halfords Carrera Vengeance 2011/12 bike:

Carrera Vengeance Mountain Bike 2011/2012 The Carrera Vengeance Mountain Bike will have you powering up steep hills and across rugged trails in no time. It has a Suntour XCM-V3 suspension fork which soaks up bumps like a sponge, and its SRAM 24-speed gears will make the afore-mentioned hills a piece of cake.

Approximate Weight (KG): 14.6kg

Forks: Suntour XCM-V3

Frame Material: Alloy

Front Brake: Tektro IO Mechanical disc brake

Number of Gears: 24

Rear Brake: Tektro IO Mechanical disc brake

Wheel Size: 26"

Cassette: 11-32T

Chainset: SRAM S200 3.0 chainset

Fork Lock-out: No

Fork travel: 100mm

Frame Colour: Satin Gunmetal

Front Mech: Shimano FD-M190

Gear Shifters: SRAM X4 trigger shifters

Gender: Mens

Handle Bars: Alloy oversize riser bars (30mm rise) (31.8mm diameter)

Headset: Semi integrated

Hubs: Alloy with Q/R

Pedals: Wellgo alloy platform

Quick Release Front Wheel: Yes

Quick Release Rear Wheel: Yes

Rear Mech: SRAM X4 rear mech

Rims: Double wall alloy rims

Saddle: Carrera

Seatpost: 350mm Alloy 31.6

Stem: Ahead aluminium stem

Suspension: Front

Tyres: Kenda Tyres

But the gears are quite bad IMHO. It takes a lot of force to switch gears. I'd also prefer bigger cranks as I pedal on roads a lot. I'm perfectly happy with the brakes and the fork.

I'm looking to buying a set online, e.g. from https://www.merlincycles.com/groupsets-81168/ , but they come in a million sizes. How do I find one that will fit my bike?

1 Answer 1


ANSWER This is a bad idea.

Your bike has 24 gears total, so its probably a 3x8. Thats three front chainrings and 8 cogs on the rear.

You could get more road speed by having a smaller small on the back, or a larger large on the front. However the default rear cassette is 11-32 and 11 is as small as they go. Your specs don't say what the front chainrings are, but on a triple MTB they're likely 26/36/46 tooth, or similar. If you put a 50 tooth front chainring on, then the FD has to be able to get there. Most simply can't handle more teeth.

If I were you I'd look at the gear cables and see that they're moving okay through the outers. The inner wires should be shiny and slide easily. A new set of inner/outers will cost you a lot less than a group and should help sort your shifting. Also measure your chain for wear (ie stretch) and if its over 1% elongated, replace it and the rear cassette if it is worn or starts skipping.

You ride on the road a lot, perhaps you could consider a dedicated road bike? If you've got the budget to buy a new groupset, you're within spitting distance of a complete road bike anyway. And then your N is 2.

Summary: You're on a hiding to nothing doing expensive part upgrades on almost any bike.

  • 1
    Thank you very much Criggie. The thing is I like this bike and can afford to pay 2-300 pounds for an upgrade. May 12, 2016 at 6:45

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