Seatylock Size Guide 2026: Pick the Lock Length, U-Lock and Mount That Fit Your Bike
The rack outside the grocery store is a fat steel post. The one at the train station is a wavy hoop. Your e-bike has a down tube as thick as a forearm and a battery in the way. And the lock you bought online? It closes around the frame, but not around the frame and the post. That's a sizing problem, not a security problem, and it's the most common reason a good lock ends up in a drawer.
Seatylock is blunt about it on its own product pages: it designs locks "to fit most bicycles," but choosing the right model for your bike's "structure & geometry is customer's sole responsibility." So we did the homework. Using Seatylock's published lengths, weights and fit notes in October 2026, here's how to match a Seatylock lock to your bike, your racks and the way you carry things.
Who This Guide Is For
- E-bike owners with thick tubes, big batteries and wide tires.
- Commuters who lock to whatever is outside the office: posts, hoops, railings.
- Scooter and small-bike riders who need something compact.
- Riders without bottle-cage mounts wondering where a lock can even live.
Fit Question 1: How Much Loop Do You Need?
A lock's reach is the thing you feel every single day. Seatylock lists every Foldylock by its locking length, so you can pick by the objects you actually lock to:
| Lock | Locking length | Price | Fits best when… |
|---|---|---|---|
| Foldylock Mini / Clipster | 75 cm | $85 / $80 | You lock frame-to-hoop at short stops, or ride a scooter |
| Foldylock Compact / Pride | 85 cm | $95 | Standard city racks and slim posts |
| Foldylock Forever | 90 cm | $135 | Busy areas and e-bikes, per the brand |
| Foldylock 95cm | 95 cm | $105 | A little more reach without stepping to 100 cm |
| Foldylock Classic | 100 cm | $125 | Thicker posts, or frame plus a wheel |
| Foldylock Elite | 110 cm | $145 | Trees, wide poles, railings and chunky e-bike frames |
A simple test before you buy: wrap a piece of string around your frame and the post you use most, then measure the string. Add a few centimetres of slack. That's your minimum locking length.
Fit Question 2: U-Lock Size vs. Your Frame
U-locks trade reach for rigidity. Seatylock's FAQ says the main difference between its Mason models is "shackle size and structure," and its alternate product names (Mason 14CM, 18CM, 22CM and 30CM) hint at how the numbers scale.
- Mason 140 ($75): "compact and lightweight," for quick stops and city commuting.
- Mason 180 ($80): the FAQ's pick "for most commuters" as a balance of security, size and weight.
- Mason 220 ($85) and 300 ($90): larger locking areas with a pentagonal crossbar; the FAQ recommends them for high-value e-bikes or overnight parking. The 300's listing graphic calls it the "widest clearance" in its category.
Smaller shackles leave less empty space inside the U, which Seatylock's own locking advice favors because it makes leverage attacks harder. Bigger shackles fit around thick e-bike tubes and wide tires. If you ride a fat-tire bike, measure tube plus post before choosing the 140.
Find the Seatylock Size for Your Bike →
Fit Question 3: Where Will the Lock Ride?
- Bottle-cage screws: every Foldylock case mounts here. Seatylock says to mount it with the opening facing up so the lock clicks fully into place.
- No bottle-cage screws: each Foldylock includes two mounting straps, and a $10 Plastic Bands Mounting Kit fits all of Seatylock's folding locks.
- E-bike batteries in the way: check that the case doesn't block battery removal or a water bottle before you tighten anything.
- U-locks: Masons don't include a bracket. The $15 U-Lock Mounting Bracket fits all Seatylock U-locks and "a wide range of frame widths," per the listing.
- Nowhere on the frame: the Clipster ($80) clips onto a belt or bag strap instead.
Fit Question 4: Chains for Odd Shapes
Chains wrap around things nothing rigid can: lampposts with flared bases, fence posts, a scooter's stem. Viking chains come in 90, 110 and 140 cm lengths. Viking Silver ($65, $70, $80) uses 7 mm square links; Viking Gold ($100, $110, $125) steps up to 10 mm links and carries a Gold rating, according to Seatylock. The FAQ says Vikings also work for light scooters, but recommends a heavier dedicated lock for motorcycles.
Seatylock Locks by Size
Prices seen on seatylock.com in October 2026 (USD).
Prices change often; the brand's site always shows the current price.
Fit Question 5: The Parts That Bolt On
Seatylock's X Lock hardware has the strictest fit rules of all, because it replaces parts of the bike itself:
- Seatpost Clamp ($30): for 28.6, 30, 31.8 and 35 mm seat tubes. Measure yours (it's often printed on the old clamp).
- Axle Nuts ($25): for solid-axle wheels, in 3/8 + 3/8 or M9 + M10 kits.
- Axle Bolts ($35): replacements for quick-release axles.
Quick Match: Your Bike, Your Lock
| If you ride… | Start with | Why |
|---|---|---|
| A slim road or city bike | Foldylock Compact or Mason 180 | Enough reach for standard racks without extra weight |
| An e-bike | Foldylock Forever, Elite, or Mason 220/300 | The brand's picks for high-value bikes and longer stops |
| A scooter | Foldylock Mini or a Viking chain | Compact loop or flexible chain around the stem |
| A bike with no mounts | Clipster, or any Foldylock with straps | Wearable, or strapped to the frame |
| Two bikes at home | A "2 units key alike" pack | One key for both, bought together |
Check Today's Seatylock Prices →
Sizing FAQ
Which Foldylock is longest?
The Foldylock Elite, at 110 cm. The Classic is 100 cm and the Mini and Clipster are 75 cm.
Will a Foldylock fit a frame with no bottle-cage mounts?
Yes. Every Foldylock includes two mounting straps, and Seatylock sells a $10 band kit that fits all its folding locks.
Which Mason should I get for an e-bike?
Seatylock's FAQ recommends the Mason 220 or 300 for high-value e-bikes or overnight parking.
What if I pick the wrong size?
Unused items in original packaging can be returned within 14 days of delivery for a refund or store credit, so test the fit without riding with it.
The Bottom Line
The right Seatylock is the one that closes around your frame and your usual post with a little to spare, and rides somewhere that doesn't get in your way. Measure with a piece of string, check your mounts, pick the length, then see our Seatylock deals page before you order. US shipping is free.
How we wrote this: SweatproofGear researched Seatylock using its official website, FAQ, product listings, spec graphics and policies in October 2026. Lengths, weights and ratings are as stated by the brand. We haven't personally tested these products and we don't invent ratings or discount codes. We may earn a commission if you buy through our links, at no extra cost to you.