Bike frame locks: tyre clearance and fitting
A bike frame lock, also known as a ring lock or horseshoe lock, stays mounted above the rear wheel and locks it in a single movement, for a coffee or a quick errand. Before choosing, take two measurements: the spacing of the seat stays, for fitting, and the width of the tyre with its mudguard, which the opening of the hoop must clear.
How does a bike frame lock work, and when is it enough?
The hoop passes through the rear wheel and stops it turning: nobody can ride off or push the bike away. On the other hand, nothing prevents the bike from being lifted and carried off. A frame lock is therefore best kept for brief stops within sight, or complemented with a plug-in chain that links the bike to a fixed point. For long stays, it accompanies a high-level D-lock or chain.
Hoop opening and fitting: the measurements to take
The opening must clear the tyre and the mudguard with a little margin. On this page, it ranges from 58 mm on the Axa Solid Plus to 63 mm on the XLC Fantomas II, 72.5 mm on the Axa Atlas Large, 75 mm on the Trelock RS 480, and up to 92 mm on the Axa Imenso and the Trelock RS 481, designed for the wide tyres of e-bikes and cargo bikes.
Fitting depends on the frame: threaded mounts on the seat stays of many city bikes and e-bikes, clamps otherwise. Manufacturers state the spacing accepted, from 89 to 112 mm for the Trelock RS 480, for example. Check that the lock gets in the way of neither the brake nor the rear rack.
Bike frame lock with a plug-in chain or cable: securing the bike
Most frame locks accept a plug-in chain or cable, whose end locks into their own lock: a single key locks the wheel and attaches the bike to a post. Axa pairs the Imenso with the UPI cable or the ULC chain, Trelock supplies the RS 430 with the ZR 355 chain, and XLC the Fantomas II with a 180 cm cable. Kryptonite plug-in chains and cables also fit Axa frame locks.
Captive key, child safety, spare key
With a captive key, the key only comes out of the lock when it is closed; with a removable key, it can also be taken out when the lock is open. Models with a child safety feature, such as the Axa Solid Plus or the XLC Fantomas II, cannot be closed while the wheel is turning. Finally, note down the key number: Axa reproduces keys when ordered online.
Other bike locks
For a longer stay, combine the frame lock with a D-lock or a chain lock. To secure the front wheel, a cable lock is enough, and the bike locks category presents every type.
Bike frame lock brands
Abus designed the Amparo 4750XL for bikes with wide wheel clearance.
Axa fits the Solid Plus with a 58 mm opening, an anti-drill plate and a child safety feature; the Imenso offers a 92 mm opening for wide mudguards.
Kryptonite offers its frame lock with a removable or a captive key, compatible with its own plug-in chains and cables as well as with Axa's.
XLC, a components brand of the Winora group, supplies the Fantomas II with a 180 cm cable; its hardened steel hoop accepts tyres up to 63 mm.
Trelock, a German manufacturer, specifies the mounting spacing and tyre clearance for each model, from 75 mm on the RS 480 to 92 mm on the RS 481, and sells the RS 430 with its plug-in chain.
Bike frame locks on sale
Frame locks from replaced ranges end up in equipment clearance, and new ones in new arrivals. The summer sales are a good opportunity to equip your holiday bike.
Frequently asked questions
Will my bike take a frame lock?
Look at the seat stays: two threaded mounts make fitting easier, otherwise a model with clamps usually works. Then measure their spacing and the width of the tyre.
Can a frame lock close while you are riding?
On models with a child safety feature, no: the bolt cannot engage while the wheel is turning. On the others, get into the habit of removing the key before setting off, which a captive-key lock requires anyway.
Removable key or captive key?
A captive key stops you from forgetting to lock and from losing the key on the way. A removable key lets you keep it on you at all times. The choice makes no difference to the resistance.
What opening do you need for an e-bike or a cargo bike?
Their wide tyres and mudguards often need 75 to 92 mm. Measure at the widest point, mudguard included, with a few millimetres of margin.
Can you use another brand's plug-in chain?
Generally not: the end piece must match the lock exactly. Kryptonite plug-ins are the exception with Axa frame locks; otherwise, stay within the manufacturer's range.
