Squeaky Brompton

[quixoticgeek]

My Brompton has gone all Dutch and developed a squeak. I think it's coming from either the hinge, Bottom Bracket, or suspension block.

Before I start randomly applying oil to anything that moves, is there anything on a Brompton that would be damaged by the application of lube (aside from the obvious of handlbar grips, saddle, tyres, and brake surfaces)?

J

[grams]

The suspension block is known for getting squeaky over time.

I don’t think there’s anywhere on a bike where a sensible person might consider putting grease that would cause it harm, but I’m not a mind reader.

[Kim]

I think it's coming from either the hinge, Bottom Bracket, or suspension block.

According to the universal law of squeaky bicycles, that means it's probably not coming from the hinge, bottom bracket or suspension block.

My favourite misdiagnosed squeak (which was happening approximately every 3 crank rotations, causing me to investigate the chain) turned out to be coming from my lungs.  Good luck!

[Jurek]

Apply furniture polish, rather than grease, to the suspension block to achieve squeak-be-gone.

[rogerzilla]

Remove bolt from suspension block.  Slather in silicone grease.  Refit.  It usually works.

[drossall]

Mine's more of a constant rattle. It developed immediately I renewed the hinge bushes last weekend. Wasn't there before

At first I was sure it was the transmission, till I stopped pedalling and the noise carried on just the same. I haven't found anything loose yet and, as I said, it didn't happen till I fitted the bushes.

Looking closely, I can see that the bolt through the suspension block butts up against the bolt through the seat lever. Could they be rattling? I've been trying to find a really good photo of how they look normally, and they seem to sit pretty close anyway.

I've tried a bit of grease. I can try it more thoroughly, but not convinced that will fix a rattle. Trying to work out whether to just try ordering a new block.

[LittleWheelsandBig]

You mean how the suspension block bolt contacts the rear clip? That is normal but usually there is enough weight that they never lose contact with each other, except over big bumps.

https://brilliantbikes.co.uk/820-thickbox_default/brompton-rear-frame-clip-retrokit.jpg

[rogerzilla]

The very stiff JK rear block (which, generally, I like a lot) loses contact a bit more frequently as there is so little squish.

I'm convinced the block's primary purpose is to provide a quiet temporary interface, rather than for suspension.  Why would you design a bike with rear suspension only?

[LittleWheelsandBig]

Because there is no extra effort in creating rear suspension when the frame design already requires a swingarm pivot.

[drossall]

I'd assumed that the suspension also helped to reduce hinge wear, which is why one review on the SJS site of the stiff JK block worries about increasing that. Any thoughts? Otherwise, I like the idea, although I'll probably try to cure my rattle first! I'll have another look this weekend.

[Kim]

Why would you design a bike with rear suspension only?

Makes sense (and is therefore common) on recumbents to reduce BRANE-rattling, but I agree the Brompton's is a side-effect of the fold.  If you did it properly it would be a Birdy.

[drossall]

Well a short test ride suggests that I may have fixed it. Embarrassing really.

I pulled and poked at the rear end, looking for a cause, and found that the wheel itself seemed to creak, and the spokes were not as taut as I'd expect. I blame the wheel builder (me). This bike has had a bit of attention recently - as well as the hinge, I've replaced the seat sleeve and also built new rims onto the hubs. Looks as though I got them a bit slack - it's impossible to say whether they'd loosened further because of not being tensioned enough to hold fast.

So I tightened them all up and voila! The sound of silence. Well, as much silence as you ever get with a Brompton.

Thanks for the comments. Several brains are often better than one on these things.