Cycling UK Forum

waveydavey wrote:I would seriouly like to see hte tandem!

Here you go:
http://www.foldingcyclist.com/Montague-TriFrame-Tandem-folding-bike.html

I can't decide whether that is the work of a genius or a madman.

Either way I like it .

I think the tandem was sold on this forum a couple of years ago. By a man in Kent, eddiewakling?? No idea where it went.

its pretty wacky that.... I can't say I think much of the cable routing for the rear brake but overall it looks a pretty good effort really.

cheers

If they had put the rear brake at the front of the seat stays the rear triangle would have fitted properly into the front one. It may have given heal problems.

I would like to thank "cycle tramp" for his complimentary review of my modified Montague BiFrame, which I used on Sustrans long distance rides back in the good old days of John Grimshaw in charge.

The original bike, which I bought new, was a cheap (£260 then) steel mountain bike that was a travesty of the name "Rudge", but it folded.

It now has pannier racks front and rear (and still folds), mudguards, 50x559 Schwalbe tyres, dynamo lights, drum brakes and North Road bars, which makes it for me a sturdy on/off road tourer that will carry full camping gear and tackle rough Sustrans routes and sandy back roads in Poland, as well as carrying a full load back from the farmers market. It will fold in half, which might be enough to count as "luggage" on a ship or train, but it makes quite a clumsy lump. Naturally, anyone with a bit of imagination could build the basic frame up into the bike that fits their personal ideal. However I mostly use a Brompton or a Fold-It for lighter touring, including camping.

Would you be kind enough to post some photos of your bike JamesGreig? I am looking for inspiration for the upgrading of my Rudge Biframe. Thanks.

Even later spotting of this thread... I have had one of these from new since the 1980's. It has been used regularly on commutes and long distance rides, on and off road, with very little maintenance. My daughter used it at university and then it was handed back. I have replaced the bar grips and not much else since setting it up with rack, mudguards etc. all those years ago. The handiest thing about the frame is just to bend it round a split fold rear seat in the back of a car. It now has panniers on with tools in for clearing the local cycle paths, including a broom that can also be taken apart easily . When you ride it people think you are an impoverished cyclist, not a classic design aficionado and no-one has ever tried to steal it!

Front mech clearance issues.
I am in the process of a parts upgrade and changed the crank set from the original SR Sakae Oval Tech (48,38,28 teeth chain rings) to a Shimano crank set (normal round chain rings, 46,36, 24 teeth). The small chain rings on the Shimano crank set means the front mech has to sit lower down to get the correct clearance. However, due to it being a braz-on mounting, the front mech will not go down far enough. The braze-on could be ground off and a clamp on mech be used but I suspect the braze-on mount was used to compensate for the shallow seat tube angle. I would be interested to hear if anyone has experienced this issue and how they solved it. Any suggestions would be gratefully received. Thank you.

the front mech mounting is an odd one for sure; it is at a funny angle to the tube it is on, presumably to allow for the offset between the BB and seat tube. Anyway you can't use a standard band-on mech because it will sit at entirely the wrong angle.

I think you have at least three options;

1) buy a mech that is meant for smaller chainrings; such things do (or at least did) exist

2) buy/make an adaptor

3) extend the extant mount by (welding) so that the mech can be mounted lower down.

When I got my Bi-Frame, someone had already cut the braze-on off, so I had to fabricate a new bracket and weld it on. It wasn't too big a deal to do that, but it would have been easier to extend a bracket that was already there, for sure.

cheers

I've replaced the chainset with a standard triple as well (probably a 48 big ring). The mech (original I think - Suntour) is right down at the bottom of the braze-on and could probably do with being a bit lower but shifts relatively well.

Interesting that the oval chainset was original, I assumed it had been added later on mine.

I was planning to try a band-on mech at some point so thanks for the point about seat-tube angle Brucey - hadn't considered that.

Thanks Brucey. I am expecting that I will have to do some metal work to sort this out. I have read some blogs on adding a front mech to small wheel folding bikes which also have odd seat tube angles. In those instances a band mounted bracket was used with the addition of a tapered spacer between the bracket and the front mech to give the correct angle.

Thenothwind. All the blue Bi-Frames I have seen have been fitted with Oval Tech bottom brackets. The white coloured Bi-Frames have had much cheaper components and round chain rings.

I think that if you are contemplating a band-on mount plus a tapered adaptor, it would surely be less work to make an adapter to fit onto the extant mount....?

The only tricky bit is using a CSK screw (or something) in the adaptor if needs be, if the head would otherwise foul the extant mech mount.

cheers

As far as I am aware, the tapered shim was an off the shelf component to in theory, assuming the correct angle shims are available, no metal working would be involved. Yes, the problem with making an adapter bracket to fit the existing braze-on bracket is the mounting screw and accommodating the depth of the head without it further compromising the position and angle of the mech.

I think I may have solved the problem and with the minimum of effort. I have elongated the slot in braze-on with a file which has allowed the mech to sit at the correct height. The angle was not quite right so I have shimmed the mounting above the clamp screw with a piece of aluminium drinks can in 3 layers. It is working with the bike on the work stand but I have not yet ridden bike with the new set-up.

simple is good! Fingers crossed...

cheers