Independent comparisons. We may earn from shop links. More info

Threadlocker for bike bolts

Updated: October 2026

A crank bolt or a fairing screw works loose, and you still need to undo it at the next service. Threadlocker for bike bolts, and for the same kind of car fastener, is a medium-strength liquid on a metal thread you will see again. It is not a substitute for the torque in the manual. UK reviews in this set name the jobs. They do not clear the brakes. The bottle rows sit on the [threadlocker medium strength comparison](/hub/diy-supplies/threadlocker-medium-strength). Peter F. read those reviews and the listings on 15 October 2026. No torque figure below is yours. A qualifying purchase through our links can earn us a commission at no extra cost to you.

A crank bolt or a fairing screw works loose, and you still need to undo it at the next service.

Our top picks

Vigorder Vigorder blue 50 ml

Best overall

Vigorder Vigorder blue 50 ml
9.6/10about £7.99
View offer
Bäder Bäder B243Eco blue 10 ml

Preis-Tipp

Bäder Bäder B243Eco blue 10 ml
9.4/10about £5.39
View offer
kintsukuroi kintsukuroi blue 50 ml

Alternative

kintsukuroi kintsukuroi blue 50 ml
9.0/10about £8.88
View offer
On this page
  1. 1.Bolts that walk loose
  2. 2.Rotors and calipers are not the same decision
  3. 3.Do not lock the wrong material
  4. 4.Leave it if you cannot torque it

Bolts that walk loose

The UK texts in this set are specific, and they are still anecdotes. Vigorder’s file mentions a fairing and a mountain bike. The shared Flintronic texts mention a crank bolt, MT10 disc bolts and a mobility scooter. Bäder’s reviews mention a Vespa clutch, BMW calipers and a KTM. kintsukuroi has a caliper-bolt review. The pattern is a vibrating metal fastener the owner expected to undo. Park Tool’s medium-strength TLR-1 is sold for bottom-bracket cups, disc-rotor bolts and stem bolts, and described as service-removable. TLR-1 is not an ASIN here. Halfords sells the high-strength TLR-2. That is the bottle you do not want on a bolt you will service. The colour choice is on blue vs red threadlocker. If you still need one medium-only bottle, the conditional pick is on the best medium strength threadlocker page.

Rotors and calipers are not the same decision

A disc-rotor bolt and a brake-caliper bolt are both near the brake, and they are not the same decision. Park Tool treats medium-strength locker as service-removable on rotor bolts that do not already carry a locking treatment, and warns that grease can migrate onto the rotor. Wipe off any squeeze-out before it reaches the disc. A caliper bolt is where a UK review stops being evidence. Bäder’s file and kintsukuroi’s file mention calipers. One Saab workshop table, for a particular 9-3, specifies Loctite 242 and a torque. That is not the figure for your car or your bike. If the manual is silent, or you cannot hold the torque, leave the caliper alone. The same limit covers steering and suspension. The sequence, including the 24-hour cure, is on how to apply threadlocker.
Vigorder Vigorder blue 50 ml

Testsieger

Vigorder Vigorder blue 50 ml
9.6/10about £7.99
View offer

Do not lock the wrong material

A bolt that threads into plastic is a known way to spin a captive nut. Motocross guidance says not to lock bolts into a plastic tank. Realth’s compatible-material cell says Plastic. That cell does not make a plastic boss safe. Permatex says its medium blue is not for plastics. Vigorder’s bullet says metal threads only. The material checks that are not bike-specific are on the medium strength threadlocker buying guide. Carbon and titanium need the maker’s note. Park Tool says its medium bottle is not for titanium. None of that is a reason to switch to red. A red bottle in the same pack turns a fairing screw into a heat job.

Leave it if you cannot torque it

The professional stop is brakes, steering, wheel studs and suspension. Those joints follow the vehicle manual. If you cannot apply the grade and the torque it names, a shop should. A stuck high-strength lock near fuel, paint or a sensor is the same stop, as is any joint that holds pressure, fuel or brake fluid. Henkel’s published 243 figures are for a test on M10 steel, not for your crank. If you cannot find the torque, stop there. Put the red bottle back unless the manual asks for a permanent grade.

Common questions

Can you use medium threadlocker on a bike crank bolt?
Yes, if it is a metal thread you will service and the maker has not forbidden it. A shared Flintronic text mentions a crank bolt, and Park Tool lists service-removable uses for its own medium-strength bottle, which is not one of these ASINs. Clean old residue, use a few drops, and wait for full cure. It is the wrong product if the bolt threads into plastic or the manual specifies grease or a permanent grade.
What about disc-rotor bolts?
Medium strength is the grade Park Tool describes for rotor bolts that do not already have a locking treatment, because you still remove them to service the disc. Keep grease off those bolts. It can contaminate the rotor. Wipe away squeeze-out. High strength is not the default. If your bike’s manual bans locker on that bolt, the manual wins over a UK review of an MT10.
Can you lock brake caliper bolts with the blue bottle?
Only when the vehicle manual names a removable grade and a torque you can apply. UK reviews mention BMW calipers and caliper bolts. A Saab workshop page shows that one maker specified Loctite 242 and a torque on a particular model. That is not your car’s figure. A review is not a roadworthiness test. If the manual is silent, or you cannot torque the bolt, leave it to a professional.
Should every bolt on the bike get threadlocker?
No. Lock the ones that walk loose and that you will undo, where the manual allows a removable grade. Leave pivots, greased threads and bolts that already have a locking patch. Old residue has to come off or the torque reading lies. A bottle on every fastener is how a plastic insert gets a captive nut spun in its boss. Medium strength is a targeted fix, not a wash for the whole bike.
What if the bolt goes into plastic?
Do not use these lockers. Permatex excludes plastics. Vigorder says metal threads only. A plastic cell on a listing, such as Realth’s, is not approval for a plastic tank or a moulded boss. Threadlocker in that hole can spin the captive nut instead of holding the screw. If the insert is already damaged, a professional repair of the boss comes before any liquid.

Related pages

Threadlocker medium strength

Best medium strength threadlocker for a bolt you undo

Blue vs red threadlocker for a bolt you will service

Medium strength threadlocker buying guide for a bolt

How to apply threadlocker so the bolt still comes apart

Sources

Henkel, the Health and Safety Executive, ISO 10964 and the Consumer Rights Act 2015, plus the amazon.co.uk listings read on 15 October 2026. Prices move. Nothing was torque-tested in a lab.

  1. Henkel UK, LOCTITE 243 (retrieved 15 October 2026)
  2. Henkel UK, choosing a threadlocker (retrieved 15 October 2026)
  3. Henkel GB SDS 817149, 11 June 2026 (retrieved 15 October 2026)
  4. HSE, GB CLP (retrieved 15 October 2026)
  5. HSE, COSHH (retrieved 15 October 2026)
  6. ISO 10964:1993 (retrieved 15 October 2026)
  7. Consumer Rights Act 2015 (retrieved 15 October 2026)
  8. Permatex medium strength threadlocker blue (retrieved 15 October 2026)
  9. amazon.co.uk listings, example Bäder B0CFR456YL (retrieved 15 October 2026)