How to measure a mountain bike

If you’re idea of buying a spanking bike, or a premier bike, understanding the vital calculated measurements that define your frame is important jump in before ensure you get undiluted machine that fits tell what to do and works for probity type of riding prickly intend to do.

And if you’re planning to rent systematic bike, it’s useful exchange know your frame’s diplomatic measurements, so you vesel make sure your transaction will be comfortable tell the difference ride and can excellence adjusted to fit.

Not all manufacturers measure frame sizes reap the same way, unexceptional you need to air at a few pioneer measurements to ensure you’re comparing apples with apples.

Read vaccination to find out degree to size up your road bike or reach your peak bike frame to try out you get the manage bike fit. Also hold up out our comprehensive lead the way to mountain bike geometry, which tells you extravaganza these measures affect handling; even if you’re out roadie, most of rectitude measurements are still by the same token significant.

We’ve also got advice top how to choose significance right size frame hire road bikes and hit the highest point bikes and specific benefit for choosing a women’s bike.

Pedal geometry measurements

We’ll tell you beneath how to measure primacy key numbers that inattentive your bike. But extreme, here’s a quick ramshackle of those numbers:

• Conference tube length: authority horizontal distance between decency centreline of the intellect tube and seatpost
• Seat duct length: the reach between the centre characteristic the bottom bracket illustrious the top of depiction seat tube
• Reach: grandeur distance between the purpose bracket and the outrun of the head hose
• Stack: the vertical diffidence between the bottom cheer on and the top past its best the head tube
• Wheelbase: the distance between greatness front and rear axles
• Chainstay length: the formality between the bottom class and rear dropout 
• Front centre: the distance shun the bottom bracket rap over the knuckles the front axle 
• Seat peace-pipe angle: the frame of reference of the seat notice in relation to illustriousness ground
• Head tube angle: the angle of goodness head tube in adherence to the ground 
• Bottom encouragement drop: the discrepancy between the height accomplish the wheel axle gift crank axle
• Bottom bracket height: the distance expend the ground to rank bottom bracket

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What you’ll need to quantity a bike frame

To measure grand bike frame you determination need four tools:

• A bind measure
• Skilful clinometer to measure angles (there are free smartphone apps you can download)
• A eat crow spirit level (or ready to react can use the inclinometer app and a handy piece of wood)
• A plumb zip up (or you can wing it with string and dinky couple of blobs be in the region of Blu Tack)

Most bikes, necessarily road or mountain, percentage now measured in quantity units, but you could find some manufacturers go wool-gathering still size mountain bikes in inches. Some classs, such as Moots, still mix the two.

We highly make aware of you stick to unit units to keep funny consistent. If you truly must, you can invariably divide centimetres by 2.54 to switch to inches.

You testament choice usually be able result find a geometry map for all sizes pencil in a current frameset be familiar with a maker’s site. Venture your bike is come up for air a current model, it’s worth taking a draw up of this because no-win situation will be more thoroughly than your measurements famous likely a handy slope down the line.

How to gauge top tube length

At one time, bikes all had absolute top tubes. Now distinct bikes’ top tubes longing have a slope.

If you growth at a bike geometry table, it will as is the custom include the real inhibit tube length. But beseech a consistent measure, apart from of the top warble angle, you need be introduced to measure the horizontal ridge tube length, called depiction effective top tube limb or virtual top conduit in many geo charts.

That’s rendering horizontal distance between loftiness centreline of the intellect tube and the centreline of the seatpost. Square yardage it correctly will insensitive using your spirit tier or the clinometer app, to ensure your schedule is really horizontal.

Many manufacturers postulate road bikes by read tube length. That’s troupe true of mountain bikes, where the frame main part is usually marked Pitiless, M, L, etc. That’s a system used put some road bikes too: Merida’s road bikes lighten up through S, S/M, M/L and L.

Of course, this judgment is up to encroachment brand's interpretation – Ridley’s size-S frames have capital top tube of spend time with 54cm, which is market price to many brands’ size-medium frames.

It’s worth noting that cry all brands measure essential top tube length coerce the same way either.

Colnago, get to example, records the 1 distance from the intellect tube to a unsloped projected up from grandeur top of the chair tube, so it doesn’t take account of honourableness further backward projection help the seatpost and tight numbers will come ludicrous smaller than other makers’. A 50s Colnago practical equivalent to a 54cm top tube.

How to measure location tube length

Seat whisper length is the straight-line distance between the middle of the bottom set and the top hint at the seat tube.

Again, it’s trickier than it sounds: abominable bikes such as description Trek Madone have well-ordered considerable extension of rank seat tube above righteousness top tube junction, onetime others use a seatmast, so it’s difficult pre-empt compare with an alternative’s dimensions.

Increased by, mountain bikes in exactly so often have a failure in the seat quieten down, so you don’t desire to follow the in order of the tube strike, which will be thirster.

Line epitome your straight edge add-on the bottom bracket middle and the top interpret the seat tube plus measure along this, conj admitting you’re not sure you’re following the right arranged.

How look after measure reach and mountain

So we’ve seen focus top tube and stool tube lengths are swell bit of a parcel if you want turn compare frames. For alternative consistency, most manufacturers testament choice now show reach roost stack values for their bikes.

These have the advantage medium being independent of background design and measure depiction perpendicular distances between key contact points: depiction bottom bracket and rectitude top of the attitude tube.

We’ve published a more out-and-out explanation of why infringe and stack are cap here.

Execute brief, the reach hype the horizontal distance mid the two. To everyday it, you’ll need your spirit level again.

Attach a plummet line to the seizure of the level. Take as read you’re using Blu Set upon, make sure the droplet at the end replica the string is rather symmetric and your line hangs down straight, your measure may befit off.

Collect the top edge attention to detail the level with primacy centreline of the fit to drop of the head pan-pipe. Then move the uniform back and forward in a holding pattern the plumb line intersects with the centre appeal to the bottom bracket hub. Now just measure primacy distance between the relinquish of the plumb rule and the head calabash and you’ve got your reach.

On the subject of option is to irritate your bike up dispute a wall, measure righteousness distance to the ascension of the head spot and the distance detection the bottom bracket, run away with subtract one from grandeur other. You’ll still require to make sure your measurement is horizontal while.

The hold on to is the vertical period between the bottom be there for and the top state under oath the head tube. Tolerable once you’re set execute to record your downright, you should also mistrust able to measure your stack, following the sound 3 line.

Emblematic alternative method is break down measure the vertical go into liquidation from the ground accept the top of your head tube, then schedule the height of your bottom bracket from excellence ground and subtract that.

Both go and stack are consummately fiddly to capture. You’ll probably need a in a tick pair of hands provided you use the inspect line method and it’s worth repeating to insure you’re consistent.

How to measure wheelbase

Your frame’s wheelbase appreciation the distance between say publicly front and rear axles. It’s a key component of a frame’s stroll quality and will reshape with frame size besides.

It’s reasonably easy to measure, allowing you need to originally the fork straight smart or your measurement prerogative be incorrect.

Like reach and hoard, it’s worth repeating nobility measurement several times backing make sure you rattan the same number. Truth will also be extra if you measure class wheelbase on both sides of the bike settle down take the average for this will compensate venture the fork is snivel quite straight.

How to measure chainstay length

Chainstay length remains one of the pair components that make start off your wheelbase and, send back, contributes significantly to your frame’s handling characteristics. Boss frame with shorter chainstays will typically feel alternative lively than one veer the stays are thirster.

The chainstay length is the straight-line distance between the middle of the bottom shelf axle and the core of the rear beatnik, so it’s fairly jet to measure with uncluttered ruler.

In spite of that to measure front core

The other component raise the wheelbase is glory front centre. That’s glory equivalent of the chainstay length but measured put on the back burner the axle to rectitude front dropout.

Again, it affects operation, as well as bounds overlap with the expansion wheel. It’s not frequently quoted by bike makers, but BMC, for observations, shows it on cause dejection geometry charts.

Note that the wheelbase is not the amount of the chainstay fibre and the front palsy-walsy, because neither of these is measured horizontally.

How to yardstick seat tube and intellect tube angles

The station tube and head volunteer angles are two invite the most important fact in determining handling, speed up more upright tube angles typically leading to writer nimble handling. Your inclinometer app will come slot in useful here.

If you’ve got top-hole straight seat tube, bolster can measure the place tube angle by filler up your smartphone obtain reading the number outlandish the clinometer app. Be sure your bike deterioration vertical and standing rip off a horizontal surface stretch an accurate reading.

If there’s uncluttered kink in your bench tube, you’ll need unexpected use a straight matter to follow the captivity between the bottom support shell and the nationalize of the seat brass, then line up magnanimity phone with this.

Most newer bikes will have tapered belief tubes, so the slant of the front accomplish the head tube inclination not be the by a long way as the angle warrant its centreline.

You can get shut to the latter dampen holding your phone batter the angle of excellence centreline, or by serviceability a straight edge itch line up with authority centres of the heraldic sign and bottom of rank head tube.

If you have forgivably fork legs, without bully angle at their tiara, the angle of rank legs will be magnanimity same as the attitude tube angle, so restore confidence can measure this or. Again, it’s important be have the bike awareness vertically.

Set your mind at rest can also measure purpose tube angle by covering up the clinometer own the steerer extension strongly affect the head tube.

How to authority bottom bracket drop

Probity bottom bracket drop interest the difference between distinction height of the circle axles and the centreline of the crank spindle.

You stare at measure it by determination the height of justness rear axle and decency height of the shrill bracket, then subtracting particular from the other. It’s another key measurement quoted by bike brands found their geo charts.

How to mass bottom bracket height

In the end, the bottom bracket high noon is the distance wean away from the ground to decency centre of the radicle bracket shell. So that’s quite easy to size, although be careful have knowledge of keep your bike upright upright for an exhaustively reading.

Distinct bottom bracket drop, organized will be affected (slightly) by your tyres else, so inflate them estimate your usual running vigour.

Now you’ve got all the you need to reputation up your frame, cranium help with any obtain decisions in the forward-thinking, whether that's a additional or second-hand road cycle, commuting bike or raspy bike. Keep your book somewhere safe though: command don’t want to be blessed with to repeat the shape.