Securing a bicycle saddle to a bike

Slightly off top­ic, but I thought it would be worth shar­ing my attempt at what might seam the tri­fling prob­lem of secur­ing a bike seat or saddle to a bike.

Brooks saddle

As many cyc­lists will know, seats or saddles can be a real tar­get for thieves — I’ve had at least two stolen. The trouble is good saddles can get a reas­on­able price on the black mar­ket. If you’re in Lon­don, just pop down to Brick Lane on a Sunday and you’ll find the coveted and pricey Brooks saddles being flogged for 10s of £s.

To save myself the cost — not to say the uncom­fort­able ride home, saddle-less — I’ve been look­ing into ways to bet­ter secure my saddle. The crude option is to use some way of lock­ing the saddle to the frame, like a small lock or part of a bike chain (see here for ideas). At the more expens­ive end there are ded­ic­ated bolts/nuts you can buy with per­son­al­ised ‘keys’, such as the Saddle Lock from Atomic22 (~£29) and options from Pit­Lock (although it’s not clear they have some­thing to bolt the seat to the seat post). These look good, but they’re quite expens­ive and I’ve found if dif­fi­cult to tell which options will fit my bike’s seat-post and saddle.

A solu­tion I’ve come up with is to use a com­bin­a­tion of a gen­er­ic secur­ity bolt and nut. I’ve found both on an online shop called Secur­ity Safety Products.

Locking the seat to the seat post

First I chose a secur­ity bolt to replace the one that attaches my saddle to the seat post. To do that I meas­ured the gauge (width) and length of the cur­rent bolt and then bought the cor­res­pond­ing secur­ity bolt and appro­pri­ate secur­ity screw.

bicycle-security bolt + screw

bicycle-security bolt gauge bicycle-security bolt length

I went for the M8 (8mm thread width) by 50mm long “Pin Hex But­ton head Mach.Screw” (M8x50mm), and the H50 secur­ity screw (the web­site tells you which screw you need).


bicycle-security bolt and seat

What you get are 10 bolts (min­im­um order) and a small screw driver insert with a spe­cial fit­ting. The lat­ter as the web­site explains “
All I had to do is replace the ori­gin­al bolt that secures your saddle to the seat post, with the new secur­ity bolt.

Locking the seat and seat post to the bike frame

original seat post nut

To secure the seat post to the bike I found a M8 secur­ity nut that fit the exist­ing seat-post bolt, again on the Secur­ity Safety Products site. You can see from the pic­ture on the left that the ori­gin­al nut was a stand­ard well-used bolt.

Also, you need to buy the spe­cific drive sock­et that fits the secur­ity nut — for me, this was a “Remov­able Secur­ity Nut 1/2 drive sock­et KM8R”.  Not sure why, but this is pretty expens­ive at £17.99, so it may be worth look­ing for oth­er options here.

The fit­ting is pretty straight­for­ward. Use a stand­ard span­ner to unscrew the ori­gin­al nut and then the drive sock­et (attached to a sock­et ratchet or wrench) to screw on the new bolt.


IMG_3747 IMG_3736

A few general comments

The down­side with this solu­tion is you can only buy a min­im­um of 10 bolts and 10 nuts, but at £14.22 and £7.90 per pack (respect­ively), it’s not too pain­ful. Don’t for­get to factor in the cost of the secur­ity screw and drive sock­et though which in my case was £3.58 and £17.99. Also, although Secur­ity Safety Products provide a good ser­vice, their postal charges are quite steep.

Of course, noth­ing is failsafe, and this idea is vul­ner­able to thieves hav­ing the right fit­tings — I don’t think that’s likely, though, not until they read this post any­way.

Nat­ur­ally, this idea won’t work with all seat and seat post fit­tings. It could work with dif­fer­ent arrange­ments though, just make sure to get the right gauged nuts and bolts and that you’ve got enough room to tighten them with a screw diver or span­ner.

If you’ve read this far and you think you need a M8 bolt or nut (and live close to East Lon­don) drop me a line. I’ll prob­ably have spares of both.


Screw driver with replace­able fit­ting.
This kind of thing.

3 thoughts on “Securing a bicycle saddle to a bike

  1. Saw this post and just wondered if you are the same Alec taylor of Fly­ing Scot Bicycle 455k if so please get back to me , if you would like to know its his­tory from 1962 to 1979.

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