SPECIALIZED BIKE SIZE GUIDE

How Specialized bikes are sized: S-Sizing, letters and frame numbers

Three systems, three different logics behind them. This is the part most riders get stuck on, so it’s worth a few minutes.

S-Sizing on Specialized mountain bikes and e-MTBs

Specialized moved its mountain bikes to S1 through to S6, and the S number is not tied to your leg length in the way old bike frame sizes were. Seat tubes are kept short right across the range, so most riders physically fit on two or three sizes. The size you pick sets the character of the ride rather than deciding if you fit at all.

• Smaller S number: shorter reach and a shorter wheelbase. The bike flicks around faster and feels playful on tight, twisty trails.
• Bigger S number: longer front end and a longer wheelbase. The bike sits calmer at speed and holds a line better on steep, rough descents.

The rule we give people in store: ride tight woodland singletrack and like throwing the bike about, size down. Ride fast open descents, rocky trails or long cross-country days, size up.

Riders who size up usually want a shorter stem to bring the bars back, and riders who size down often want a longer dropper post. Both are quick swaps, and we sort them at the point of sale.

You’ll find S-Sizing on the Specialized mountain bikes at the trail and cross-country end of the range, including Stumpjumper, and on the Turbo Levo. Specialized has been rolling it across more models each season, so check the geometry chart on the model you’re looking at.

Letter sizes (XS to XXL) on Specialized hybrids and e-bikes

These behave the way people expect, and they are the same letter sizes used across hybrid bikes generally. One frame per height band, read straight off the bicycle size guide charts above.

One thing worth adding for step-through and low-entry frames like the Sirrus step-through and parts of the Turbo Vado range. With no top tube in the way, standover stops being the limiting factor, so reach and saddle height do the deciding instead. A borderline rider can often take the smaller frame on a step-through and be perfectly comfortable on it.

Number sizes on Specialized road bikes

If you’re sizing a Specialized road bike, the names are different again. A 54cm Specialized road frame does not have a 54cm seat tube. Modern compact geometry dropped the top tube at the back, and the number stayed on as a size label from the days of level top tubes.

The measurement that tells you how a road bike will fit is reach. So don’t line up a 54cm Specialized against a 54cm from another brand and assume they’ll feel the same, because they very often won’t. Compare reach and stack instead.

What each measurement on a bike frame size chart means

Read this as a bicycle measurements guide as much as a size chart. Once these terms make sense, every bike dimensions chart on the internet becomes usable, including the geometry tables on Specialized’s own product pages.

Reach. The horizontal distance from the bottom bracket to the top of the head tube. This is how stretched out you’ll be, and on modern bikes it matters more than any other single number.

Stack. The vertical distance from the bottom bracket to the top of the head tube. More stack puts you in a taller, more upright position. Less stack drops you lower and more aerodynamic.

Seat tube length. The old way of labelling frame size, and the reason road bikes still carry numbers. Useful for checking seatpost insertion, less useful for working out fit.

Effective top tube. The horizontal distance from the head tube to the seatpost. Handy as a bike length chart when you’re comparing an older bike against a new one.

Standover height. How high the top tube sits when you straddle the bike with both feet on the ground. This is a safety number.

Wheelbase. The distance between the two axles. Longer is steadier at speed, shorter turns in quicker.

Head tube angle. A lower number means slacker, which calms the steering down on descents. A higher number means steeper and sharper handling.

Read any bike chart frame size as a starting point rather than a ruling. Specialized publishes a full bicycle frame size chart on every product page, and our team will happily read one through with you over the phone or in store.

Between two sizes on a Specialized bike? How to choose

Most people land here because their height sits on the line between two rows. What follows is what we’d tell you across the counter.

Road bikes. Default to the smaller size. A slightly short frame can be stretched out with a longer stem and a setback seatpost. A frame that’s too long can’t be shortened much before the steering starts feeling odd. Go smaller if you’re new to drop bars, if you have short arms for your height, or if touching your toes is a struggle. Go larger if you’re an experienced rider with a long torso who wants the position low and stretched.

Mountain bikes. Riding style decides it, as covered in the S-Sizing section above. Check dropper post length before you commit, because a tall rider on a smaller S size can run out of seatpost insertion depth.

Hybrids and commuters. Standover and comfort win. If you’ll be putting a foot down at traffic lights all day, the extra clearance on the smaller size is worth having.

E-bikes. Size down when you’re borderline. A Turbo Vado or a Turbo Levo carries a lot more weight than a normal bike, and being able to plant both feet flat at a stop makes an enormous difference to how confident it feels. Worth thinking about how you’ll lift it onto a rack or up a step, too.

A few things that push the decision either way:

• Long arms or a long body for your height, size up.
• Short reach, or wrist and shoulder trouble, size down.
• Coming off a bike you loved? Bring us its reach measurement, and we’ll match it. It’s the most reliable shortcut there is.

How to check the fit once you’re on the bike

Five checks, in the order we do them in store.

1. Standover clearance. Straddle the bike with both feet flat. Aim for 2 to 3cm of clearance on a road bike and 5 to 10cm on a mountain bike, where you’re more likely to be stepping off in a hurry. Skip this one on a step-through frame.
2. Saddle height. Put your heel on the pedal at its lowest point. Your leg should be straight with your hips level, no rocking side to side. Move to the ball of your foot and you’ll have the right amount of bend. For a starting number, saddle height measured from the centre of the bottom bracket to the top of the saddle works out at roughly 0.883 times your inside leg in centimetres.
3. Knee position. With the cranks level, drop a plumb line from the front of your kneecap. It should fall through the pedal axle or thereabouts. Slide the saddle forwards or backwards on its rails to sort it.
4. Reach. Hands on the bars, elbows slightly bent, shoulders relaxed and down. If you’re locking your elbows out or shrugging up towards your ears, the reach is too long. If your knees clip your elbows as you pedal, it’s too short.
5. Bar height. New riders and anyone with a stiff back should start with the bars higher than they think. On a road bike we can move spacers under the stem or flip the stem to lift the front end without changing frame size at all.

A bike that fits should feel comfortable inside ten minutes. Anything that doesn’t feel right after that is usually a contact point we can change, rather than a sign you need a different frame.

Why your Specialized size changes across the range

Take a rider at 178cm with an 82cm inside leg. Run through the charts above and here’s what comes out:

• Road (Tarmac, Roubaix, Allez, Diverge): 56cm
• Sirrus hybrid: Large
• Turbo Vado e-bike: Large
• Rockhopper: right on the Medium and Large line
• Stumpjumper: anywhere from S3 to S5, depending on how they like to ride

Same body, five different answers. Each discipline puts you in a different position on the bike, so the same rider needs a different frame to reach each one. Your road size doesn’t carry across to your mountain bike, and neither carries across to a step-through commuter. Read each bicycle frame size guide on its own terms.

Women’s fit on Specialized bikes

Specialized retired its women’s specific frames a few years back and now sells everything as unisex. Every frame in the charts above fits any rider, and there’s no separate women’s geometry to hunt for.

What changed instead was the spec. The smaller frames come with a wider, shorter saddle and narrower handlebars as standard, because those parts suit the riders most likely to be on that size. There is some personal preference involved: a woman on a large frame may want a saddle swap, and a man on a small frame sometimes wants the same change in reverse. The frame size is right, the contact points might need a look.

Here’s what we change and why:

• Saddle width, to match your sit bone spacing. We can measure this in store.
• Handlebar width, to match your shoulders rather than the box the bike came in.
• Crank length, which takes pressure off the hips for riders with shorter legs.
• Stem length, to bring the bars closer or push them further out.
• Brake lever reach, adjusted in for smaller hands so you can brake from the drops with confidence.

If you’d rather have a frame designed around female-specific geometry from the ground up, the Liv range is worth a look and we stock it. It is also worth browsing our ladies and womens bikes and our mountain bikes for women.

More sizing help here: Women’s Hybrid Bike Sizing Guide and Women’s Mountain Bike Sizing Guide.

How to size a Specialized kids bike

Kids bikes are sized by wheel diameter rather than frame size, so a 20in wheel bike is a size in itself. The age ranges on any cycle size guide are a rough steer, because two nine-year-olds can be 15cm apart in height.

Measure your child’s inside leg the same way you’d measure your own, then use these checks:

• First pedal bike: they should sit on the saddle with both feet flat on the floor. That’s what gives a nervous rider the confidence to stop.
• Once they’re riding confidently: tiptoes on the floor is fine, and it gives them a much better pedalling position.
• Standover: they need clearance over the top tube so they can step off quickly without catching themselves. This is the one we won’t budge on.
• Room to grow: one size up is sensible if they’re near the top of a band. Two sizes up isn’t, because a bike they can’t control is a bike they stop wanting to ride.

Balance bikes work differently again. There are no pedals to reach, so saddle height is the only measurement that counts, and you want it low enough that they can walk the bike along flat-footed.

Full chart here: Children’s bikes size chart

What we change in store to fine-tune your Specialized fit

A frame size gets you close. These are the parts we swap or adjust to close the gap, and they’re the reason two riders of the same height can both be comfortable on the same bike.

• Stem length and angle, for reach and bar height
• Saddle, for width and shape
• Seatpost setback, for knee position over the pedal
• Handlebar width, plus bar drop and reach on road bikes
• Crank length, for shorter legs and hip comfort
• Brake lever reach, for smaller hands
• Spacers under the stem, to raise or lower the front end

This is where nearly 50 years of putting people on bikes shows up. A chart can tell you that a 178cm rider takes a 56cm road frame. It can’t tell you that your shoulders want 40cm bars instead of 42cm, or that your knee sits 2cm forward of where it should. That’s what a fitting session is for.

Come and sit on the bikes at one of our stores, take one out on the road, and we’ll set it up around you before it leaves. If you order online and the size turns out wrong, get in touch and we’ll sort it.

Frequently Asked Questions

What size Specialized bike do I need for my height?

Measure your height with your shoes off, then read it against the chart for the model you want above. As a rough steer, a 175cm rider is usually a Medium or Large hybrid, a 56cm road bike, and an S3 or S4 mountain bike. The exact answer depends on the model, so use the charts rather than a single number.

How do I measure my inside leg for a bike?

Stand against a wall with your shoes off and your feet 15cm apart. Pull a hardback book up between your legs with firm pressure, spine upward, keeping it level. Mark the wall at the top of the spine and measure down to the floor. That’s your inside leg, and it’s what settles things when you’re between two sizes.

What do S1, S2, S3, S4, S5 and S6 mean on a Specialized bike?

They’re Specialized’s mountain bike sizes. The number changes reach and wheelbase rather than seat tube height, so most riders fit on two or three of them. A lower number handles quicker on tight trails. A higher number is steadier at speed and on steep descents. Pick by riding style rather than by height alone.

Is a 56cm Specialized road frame the same as a Medium?

Roughly, yes. Specialized labels road bikes with numbers and mountain bikes with S sizes, so there’s no direct swap between the two. A 56cm road frame suits about the same height range as a Large hybrid, though the riding position is far lower and longer.

I’m between two Specialized sizes. Should I go up or down?

On a road bike, go down. A short frame can be stretched with a longer stem, and a long one can’t easily be shortened. On an e-bike, go down as well, because being able to put both feet flat on a heavy bike matters. On a mountain bike, size down for playful handling and up for stability. On a hybrid, go with the one that gives you better standover.

What size Specialised Rockhopper do I need?

The Rockhopper runs from Extra Small through to Extra Extra Large, covering riders from about 148cm to 200cm. Use the Rockhopper chart above, and note that the wheel size changes with the frame size across the range, with smaller frames on smaller wheels to keep the handling right. Some people spell it Specialised Rockhopper with an s, and it’s the same bike either way.

Does Specialized sizing match Giant, Trek or Whyte?

No, and this trips people up regularly. A Medium from one brand can be 20mm different in reach to a Medium from another. Compare reach and stack numbers from each brand’s geometry chart rather than trusting the letter or the number on the frame.

Are Specialized bikes still made in women’s sizes?

Specialized dropped its women’s specific frames and moved the whole range to unisex sizing. The smaller sizes tend to come with narrower bars as standard. If you’re a woman on a larger frame, a saddle swap is usually all it takes to get comfortable. Talk to us about options.

Do Specialized e-bikes use the same size chart as normal bikes?

Close, and there are separate charts for Specialized electric bikes above because the bands shift slightly. The bigger difference is the advice: on a heavier e-bike, err towards the smaller size so you can plant both feet at a stop.

How much standover clearance should I have?

Around 2 to 3cm on a road bike and 5 to 10cm on a mountain bike, measured with both feet flat and the bike upright between your legs. Step-through frames don’t need the check at all.

What size Specialized bike should I buy for my child?

Go by wheel size and their inside leg rather than their age. On a first pedal bike they should reach the floor with both feet flat. Once they’re confident, tiptoes is fine. Never size up more than one step, however tempting the growing room looks.

What happens if I order the wrong size online?

Before you order, it’s worth sending us your height and inside leg with the model you’re after, and we’ll confirm the size for you first.

Still not sure? Come and see us, or browse the full range of Specialized bikes and the road bikes we stock alongside them.