Rudge 'Bi-Frame' -a 'Proper' Folding Bike....?

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Bazzr
Posts: 2
Joined: 25 Jun 2019, 12:19am

Re: Rudge 'Bi-Frame' -a 'Proper' Folding Bike....?

Postby Bazzr » 25 Jun 2019, 12:35am

Hi folks, just thought I'd add to this as I've got a biframe. Brought it in about 91 as a bike to get to work on for £70. Was a 18 speed with oval chainrings. It was unused between 98 and 2015. When I pulled it out of the shed. The majority of the components were shot. I decided it would be piontless to return it to original, as I have other modern bikes that would do the job better. So a single speed it was.
Baz
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Brucey
Posts: 36116
Joined: 4 Jan 2012, 6:25pm

Re: Rudge 'Bi-Frame' -a 'Proper' Folding Bike....?

Postby Brucey » 25 Jun 2019, 12:50am

nice!
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fastpedaller
Posts: 2140
Joined: 10 Jul 2014, 1:12pm
Location: Norfolk

Re: Rudge 'Bi-Frame' -a 'Proper' Folding Bike....?

Postby fastpedaller » 25 Jun 2019, 10:29am

That looks good. I did consider the simplicity of single speed for mine, but decided (as I take the wheels out to fold it and transport in the boot or caravan to car shows) that a derailleur made it easier re chain dropping off. I have only 5 speeds (using unused or little-used spare shimano sprockets) onto a freehub with suitable spacers.

random37
Posts: 1945
Joined: 19 Sep 2008, 4:41pm

Re: Rudge 'Bi-Frame' -a 'Proper' Folding Bike....?

Postby random37 » 25 Jun 2019, 10:43am

Regarding bottom brackets on these and singlespeed conversions.
Mine is still on the original bottom bracket, which I suspect won't be good enough for another rebuild. There is the problem with the seat tube intruding into the shell.
The quality of cup & cone bottom brackets is pretty poor these days. So come rebuild time, I am considering using a Euro BB from a BMX like this:
http://www.alansbmx.com/1654373/product ... indle.aspx
Probably heavier than an MTB one. But who cares?
Has anyone fitted anything like this? It looks like it would fit, but I know very little about BMX. As far as I know, Euro BBs are the same thread/diameter/width as conventional BBs on modern bikes.

Bazzr
Posts: 2
Joined: 25 Jun 2019, 12:19am

Re: Rudge 'Bi-Frame' -a 'Proper' Folding Bike....?

Postby Bazzr » 25 Jun 2019, 11:16pm

Hi randam37,
I didn't come across the problem with the seat tube conflicting with the shell of the BB bearings because I have used the modern external type deor bearings and chainset that current in 2015. Same thread and same width so the modern parts solved a problem I didn't no I could of had - few. I have managed to mix modern stuff with old quite well with this bike. My only issue with it is. I used tiagra brake levers which I chose because they are adaptable to all brake caliper types. I don't think the cable pull ratio is enough for these old (dia comp) canterlevers. I think that the modern canterlevers must have a different pull ratio. But hay ho, the brakes weren't much better on the original levers.
Baz

Brucey
Posts: 36116
Joined: 4 Jan 2012, 6:25pm

Re: Rudge 'Bi-Frame' -a 'Proper' Folding Bike....?

Postby Brucey » 25 Jun 2019, 11:36pm

random37 wrote:Regarding bottom brackets on these and singlespeed conversions.
Mine is still on the original bottom bracket, which I suspect won't be good enough for another rebuild. There is the problem with the seat tube intruding into the shell.
The quality of cup & cone bottom brackets is pretty poor these days. So come rebuild time, I am considering using a Euro BB from a BMX like this:
http://www.alansbmx.com/1654373/product ... indle.aspx
Probably heavier than an MTB one. But who cares?
Has anyone fitted anything like this? It looks like it would fit, but I know very little about BMX. As far as I know, Euro BBs are the same thread/diameter/width as conventional BBs on modern bikes.


its an interesting thought, but you either need to use BMX cranks to fit the BMX spindle or to replace the spindle with something else. IIRC BMX spindles come in 19, 20, and 22mm types, but not all are possible inside a BSC threaded bottom bracket shell. BTW the standard BMX spindles appear to be ~145mm long, which means you probably have a minimum width across the pedal mountings of at least 155mm, thus this scheme isn't for those that favour low Q. The BMX bottom brackets allow for different shell widths by spacing the cranks away from the bearings by using a stack of spacers; this allows the chainline and the bearing preload to be fine-tuned.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

random37
Posts: 1945
Joined: 19 Sep 2008, 4:41pm

Re: Rudge 'Bi-Frame' -a 'Proper' Folding Bike....?

Postby random37 » 26 Jun 2019, 8:23am

My understanding is the Euro BB is the same size as an MTB bottom bracket (actually, there are two different shell widths). There are larger sizes (Mid and Spanish), which would require a different size frame.
A BMX crank is what I'd use. You can get square spindles, but the crank it has now could be useful somewhere else.
What appeals is the ease of adjusting chainline with spacers. As the next iteration of mine will either be 3- or single- speed, it is quite appealing. My understanding is it might be hard to replicate the chainline of an MTB singlespeed hub with many standard BMX cranks, but I won't be running particularly fat tyres so clearance isn't an issue. Probably just an el cheapo freewheel hub built without dish. I need to have a look what's in my parts bin.
Watch this space!

fastpedaller
Posts: 2140
Joined: 10 Jul 2014, 1:12pm
Location: Norfolk

Re: Rudge 'Bi-Frame' -a 'Proper' Folding Bike....?

Postby fastpedaller » 26 Jun 2019, 9:05am

My Rudge Bi-Frame has a Shimano cartridge Square Taper BB - There was just enough clearance (the ID label came off in the process :lol: )

Brucey
Posts: 36116
Joined: 4 Jan 2012, 6:25pm

Re: Rudge 'Bi-Frame' -a 'Proper' Folding Bike....?

Postby Brucey » 26 Jun 2019, 9:24am

re the BMX bearings; I dunno how strong or long-lasting those BMX bottom bracket bearings really are; BMXers probably have a different expectation from other riders. The cartridge bearings themselves have to be fairly thin section bearings (and I'm not sure they are an industrial standard size either) and I would assume that the load rating of each bearing isn't very high; there are two bearings side by side in each cup and the balls in them can't be much more than 3mm diameter. The ability of these bearings to share the load properly is limited by

a) the tolerance of the bearings (SKF usually supply similar bearings in matched pairs, and suggest that the load rating/life is reduced if an unmatched pair is used) and
b) the alignment tolerance of the BB shell; even with 'perfect bearings' if the BB shell isn't perfectly aligned the bearings won't share the load properly.

Similar considerations apply to quite a few bottom bracket systems and often unseen design features are included which mitigate such problems; for example in HT-II bottom bracket bearings, the cartridge bearings are mounted in a seating that allows the bearing to articulate very slightly should the need arise. Where this isn't possible (e.g. in ISIS bottom brackets) you end up with multiple rows of tiny balls that make for similarly problematic sealing/ load sharing and (usually) a relatively short life. I suppose one way of looking at it is if your envisaged use of the bike matches that of a BMX bike you might be alright...?

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

random37
Posts: 1945
Joined: 19 Sep 2008, 4:41pm

Re: Rudge 'Bi-Frame' -a 'Proper' Folding Bike....?

Postby random37 » 26 Jun 2019, 9:29am

My assumption is almost anything would be better than the cheap tat available in cup and cone land these days.
Expect a new post when the need arises.

Brucey
Posts: 36116
Joined: 4 Jan 2012, 6:25pm

Re: Rudge 'Bi-Frame' -a 'Proper' Folding Bike....?

Postby Brucey » 26 Jun 2019, 9:53am

you might be right, but I also note that

a) very many frames are built with imperfectly aligned BB threads which does not auger well for that bearing arrangement and
b) the 'cheap tat' is almost invariably treated as cheap tat and thus the seeds of doom are in the thing when it is installed.

On the latter point the same is true of lots of cheap hubs too. However given decent setup and lubrication, many fairly inexpensive hubs can have perfectly acceptable service lives.

On the BB front there is no way to know exactly what you are buying (and YMMV too) but I've taken cheap three-piece BBs, installed them using loose balls, good quality grease, and good adjustment, and they have worked OK. Certainly comparable with or better than the performance/lifetime I get from cheap BBs which use cartridge bearings.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

fastpedaller
Posts: 2140
Joined: 10 Jul 2014, 1:12pm
Location: Norfolk

Re: Rudge 'Bi-Frame' -a 'Proper' Folding Bike....?

Postby fastpedaller » 26 Jun 2019, 11:11am

fastpedaller wrote:My Rudge Bi-Frame has a Shimano cartridge Square Taper BB - There was just enough clearance (the ID label came off in the process :lol: )


I add that mine is also a blue one, and although the colour isn't important :D it appears it has a bearing (no pun intended) on the timing of the frame's production and associated small design changes - It may be that blue ones like mine will all accept a Shimano ST cartridge?