New S5EX Brommie NiTi Special :-)

[chriscross1966]

Once I've finished off the next couple of planned bikes for which I have most of the components to hand, (a T3 that will be getting an 8-speed Sturmey hub and a nice crank and a drop-bar conversion on an M3 with a lot of Campagnolo bits as a 14-speed derailleur bike) I might well revisit this. With some re-engineering I could rebuild a steel rear frame triangle to accommodate even larger chainrings, but on a better chain line, from memory a normal bottom bracket height will allow around 104t chainring. It will need cut outs in the rig to accept folding, but it would be an interesting challenge...

 

[Kell]

When your chainring is as big as your wheels, I think you'll have gone too far.

Would 104T be bigger than 16"?

 

[T4tomo]

I like the black and silver look and the bars, but the chain ring just looks daft to me.

I cant think of a reason why you would want large chain rings and large sprocket over something more normal sized to give equivalent gearing.

 

[Cycleops]

Puts me in mind of Rowan and Martins Laugh in back in the late sixties/seventies? When that WW2 German soldier popped up saying:

 

[TheDoctor]

Normally 'Because I can!' is a perfectly reasonable response to any question that starts 'Why'.
In this case, I do begin to wonder.
I could get my M12R up to a 114" gear by fitting a standard double (53T outer) and swapping the small rear sprocket for a 12T.
I could still pedal that at 60+mph. Just.
60mph on a Brompton would scare me witless. 45mph was dodgy enough!

 

[Ridgeways]

I could get my M12R up to a 114" gear by fitting a standard double (53T outer) and swapping the small rear sprocket for a 12T.

I once geared my Bickerton with a 120" plus set up, but I rarely got a chance to use it, and the extra width of cassette made changes too troublesome. That was using my 68 tooth chainwheel together with a Moulton 9 tooth sprocket.

 

[chriscross1966]

When your chainring is as big as your wheels, I think you'll have gone too far.

Would 104T be bigger than 16"?

Ermm... possibly, quick calculation... Yes... I'm running 28-349 tyres so my rolling diameter is a shade under 16" and a 104 chainring is 16 7/8"..

 

[chriscross1966]

I like the black and silver look and the bars, but the chain ring just looks daft to me.

I cant think of a reason why you would want large chain rings and large sprocket over something more normal sized to give equivalent gearing.

Each to his own I guess, I personally like big chainrings :-)

 

[chriscross1966]

Puts me in mind of Rowan and Martins Laugh in back in the late sixties/seventies? When that WW2 German soldier popped up saying:

View attachment 372366

If I wanted sensible I'd leave them stock.... but I can't help myself... I've got a Moulton mini that is going to be getting a carbon-fibre Campagnolo crank in the near future...

 

[chriscross1966]

Normally 'Because I can!' is a perfectly reasonable response to any question that starts 'Why'.
In this case, I do begin to wonder.
I could get my M12R up to a 114" gear by fitting a standard double (53T outer) and swapping the small rear sprocket for a 12T.
I could still pedal that at 60+mph. Just.
60mph on a Brompton would scare me witless. 45mph was dodgy enough!

I'm a fairly low cadence kind of guy, the current gearing on my 11-speed is from under 30 at the bottom to over 120 at the top, that top gear doesn't see much use... I'm plannin gon gearing down a bit as I do the shopping on that bike and it would be helpful if it had some lower gears, I could add the trailer to it... The 8-speed I want to keep low anyway, but weirdly because the Sturmey hub starts from 1:1 you need to run (to my eyes) tiny front rings to do that... it'll probably end up at around 34:20 on a Campagnolo Mirage Compact (one of the old Ultratorque ones)... the 14-speed goes back to big rings again, a set of Specialities TA 61/46 TT chainrings on an old Campagnolo Victory chainset they'll be running the unfortunately non-campy 11-28 7-speed freewheel........

 

[TheDoctor]

Oh, far be it from me to decry someone else's bike setup. I mean, I wouldn't do it that way, but that doesn't mean you're wrong, it just means we ain't the same
If it works, it's right. For varying values of right.

 

[Fab Foodie]

Hi @chriscross1966
Still interested in the bar set-up. Is it possible to see some photos of the bars when folded?
Would longer bullhorns fit?

 

[chriscross1966]

Hi @chriscross1966
Still interested in the bar set-up. Is it possible to see some photos of the bars when folded?
Would longer bullhorns fit?

I'll dig some out. Apparently if you fit longer bull horns they will wrap round the wheel, I wanted to keep the cockpit fairly narrow. Old mountain bike 48cm or bigger should get you there though... you'll probably end up having to run fairly skinny tyres, Kojaks, not Marathons...

 

[chriscross1966]

Viewed from above to show fold and extended handlebar clip setup

Persephone folded

• chriscross1966
• 14 Sep 2017

 

[chriscross1966]

Viewed from above to show fold and extended handlebar clip setup

Persephone folded

• chriscross1966
• 14 Sep 2017

That's an aftermarket carbon fibre clip and a 30mm extension in the mushroom made from a stainless tube nut and a grubscrew (plenty of loctite)