Cycling UK Forum

Thanks Brucey. I will report back when I have given it a good test.

Revival of old thread alert!
I think the Rudge Bi-frame is a great idea. I notice the seat tube was described as 'very laid back' or similar...... do we know what the REAL angle is though? ie it's not the angle of the tube that matters, but the angle of the line that joins the centre of the bottom bracket to (pretty much) the centre of the seatpin. This is 'variable' because the seatpin will extend along the line of the seat tube, but I hope it makes sense. The key point being that the bottom bracket (being behind the seat tube) gives us a steeper angle than it would indicate by looking at the seat tube.

like you say the angle isn't really a fixed angle, because the seat tube doesn't pass through the centre of the BB.

I've never tried to measure the angle per se but I do know that to get the saddle in the right place wrt to the BB (as measured using a plumb-line and a ruler to the saddle nose) I need to have the saddle well forward. I presently have a standard (i.e. non-microadjust, steel) clip set the wrong way round (i.e. forwards of it) on a plain steel seat pin to get the saddle in the right place.

Maybe a triathlon-specific seat pin would work, but it is a funny diameter. I think an inline post might just work but I don't think it would be kind to the saddle rails and it would not work with every saddle; AFAICT the saddle would be as far forwards as it would go. Maybe a VK adapter used the wrong way round?

Whilst the arrangement I have is working OK there is not that much incentive to improve it TBH.

cheers

Thanks for the very swift response. If one comes up nearby I may well be tempted. I wonder how easy (difficult) it would be to convert (maybe 2 bikes?) to make one like this. It could be a useful way to modify it to take a cartridge bb, however I can see the seat tube angle needs to be shallow in order to get the fold to work.

I have idly thought about doing the same thing; the rudge frame is much heavier than it needs to be (for my use) and you could easily make the same thing about two or three lbs lighter, I reckon.

However there are issues; the funny seat angle and the weird BB position are to allow the rear triangle to fold into the main triangle. Whilst it looks as if a compact rear triangle would fold into a conventional main triangle, you would have the chainstays above the BB (so would clash with the small ring/chain perhaps) and they would be at the wrong angle to the DT, obstructing the fold, unless you make the seat tube a funny angle. If you have a large rear wheel and a smaller front one, the angles work out better but that is a very different bike and certainly not one you can easily make by cutting up a couple of ordinary ones.

One mad idea I had was to allow a separate chainstay clamp and seatstay clamp to slide up and down the seat tube and to have the joints to/between the clamps/stays pivoted. This would perhaps allow the stays to fold into the main triangle even with a conventional layout of the main triangle. You would need to find a way of stopping the clamps from sliding on the seat tube in service though.

cheers

A bit more digging has revealed that in the USA the Montague Bi-Frame design was also sold as

- BMW 'Active Line' (RRP of 995USD... )
- Schwinn
- A special version was also made for the Atlanta Olympics

BMW version (with 700C wheels?)


Yellow BMW version (26" wheels)

note top tube cable routing; different to other BiFrame models

Schwinn version

the rear dropouts look very similar to the ones on black rudge branded bikes

[img]transmission%20is%20shimano%20200GS[/img]

BMW Atlanta version


some more info here
http://blog.graywriterrv.com/?p=856

There was also a Fuji Marlboro bike sold in the USA

which may also be a Montague design. Once the seat pin is pulled out the bike folds around a vertical axis including the joint onto the top tube.


[edit; note that both the Fuji and 'Olympic' designs have no seat tube that is continuous with the front part of the frame. This will probably mean a marked reduction in torsional stiffness is likely in these frames.]

This one



has been heavily modified; I barely recognised it.

cheers

more photos (some rounded up from other threads);

someone's project from retrobike;

based around a 'small' black frame. IIRC he calls it a 'Rudge Bi-Plane'.... Note lack of mudguard clearance if >2" tyres are fitted.

a small black one with some non-standard parts


a standard condition 'blue one' (large size)




small size blue one

fitted with rack, that will prevent it from folding...

large size blue one, with non-standard forks I think


another blue one (advertised on LFGSS several years ago)



allegedly has similar parts to 'the black ones'

Suntour Accushift XCE derailleurs and gears (3x7)
SR Sakae 'Ovaltech' Biopace-style chainrings
Joytech hubs/Araya rims
Dia-Compe levers and cantis

Note the 'blue ones' have shorter dropouts (of better quality) than the black ones (which have pressed steel rear dropouts), but the black ones would convert to a SS/IGH more easily.

cheers

disguised as a normal bike


large black frame

note long slotted dropouts

large black frame unfolded

and folded


details of montague/BMW 700C model (note different rear brake hanger)

Montague started producing BMW branded bikes in 1992

Schwinn advertisement (1991)


montague 'tri-frame' tandem (two hinges.... )




SS converted Schwinn montague (yes the green transfers are standard with that frame colour; makes the black rudges look tasteful, no..?)

I'm thinking V brakes would make a good alternative to the standard cantis - can anyone suggest why that's not a good idea?

Not a bad idea, per se. But the cable routing on mine is odd, for the folds.

I think I will put my Maguras on it when the old brakes stop. Cable routing is less important. I like the idea of it being singlespeed too.

fastpedaller wrote:I'm thinking V brakes would make a good alternative to the standard cantis - can anyone suggest why that's not a good idea?

the black Schwinn with the lurid green transfers has V brakes; doesn't look too bad to me. Bosses are set to the correct spacing etc.

Slight worry is if the brakes are left unhooked when the bike is folded; they will stick out more than cantis and maybe interfere with something (eg the down tube perhaps with the front brakes). Another worry is if the cable housing for the rear brake takes a set and alters the centring of the rear brake.

cheers

well I'm not cured yet; I just bought another one; it came up local to me and wasn't too much money so I had it. It is large frame size black one, a bit tatty but low mileage and with pretty much all original parts on it, apart from the brakes I think which are the cheapest and nastiest C-star cantis in glorious pressed steel. I don't remember these being originally fitted...???

Not quite sure what I'm going to do with it but I have previously wondered if a large frame size might suit me better and have improved ride quality vs a small frame size (which I have already, another black one). If I can round up enough parts then I shall build them both up 'the same' (including tyres etc) and be able to ride them back to back for comparison purposes.

The frame is about thirty years overdue for a shot of grease; it only folds with some difficulty, but it will come right, I am sure.

cheers

Funny you should say about another one......... I've been on the lookout for one for about a year, and recently bought one (other thread). A friend's Father-In-Law had one but wouldn't part with it and (I'm sure your ahead of me here), so it looks like I may also have two soon. The one I got recently was advertised as 19'5 inches, but is actually 21.5 inches (search me how the seller measured 19.5), but not critical.

owners manual here

http://www.retrobike.co.uk/gallery2/d/87102-2/ARCHIVE_Biframe_Owners_Manual.pdf

slightly different owner's manual here

http://www.veterancycleclublibrary.org.uk/ncl/pics/Rudge%20Bi-frame%20Manual%201992%20(V-CC%20Library).pdf
supplied in Jan 1992, together with a white BiFrame

NB the manual above also has pictures of the (now well used) bike the manual came with.



1991 was when Schwinn first offered the Montague design for sale. Not sure when the Rudge version first appeared?

[edit; this page http://www.classicrendezvous.com/British_isles/Rudge_main.htm suggests ~1989, which is what I remember too; the first ones had SunTour 6s indexed gearing; couple of years later and they had moved on to 7s gearing.]

[edit this page http://www.foldsoc.co.uk/offroad.html mentions that Tony Hadland uses a BiFrame for offroading, in preference to other folding bikes.]

The BiFrame folding design is known as the 'concentrus' system, and was patented in 1987
http://patft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=5975551.PN.&OS=PN/5975551&RS=PN/5975551

cheers

there is one on e-bay at present

https://www.ebay.co.uk/itm/173678347101

slightly above average asking price, but then again it looks in good shape too, so maybe that is OK. It is a blue one in the large frame size.

cheers