Folding Bikes - Front derailleur on Downtube NS

I am planning to add a front derailleur to my Downtube NS. I added a triple crank a while ago and have been shifting with my foot. My idea is to bolt or weld a tube against the front edge of the seat stay to hold the derailleur bracket, hopefully of the same diameter as the bracket uses. Then attach a friction shifter to the downtube with just a short cable to the derailleur.I am hesitating though as I am not sure if I have considered everything and don't want to screw it up. Any thoughts or ideas would be appreciated.

The NS has either a 34.9 or 40 mm seat tube diameter. Why not use a braze on clamp to mount the front derailer?

I believe that the Dahon clamp is 40 mm.

be sure you're using a wide enough BB axle as the fat seat tube will move the FD out more than a regular tubing size MTB or road bike.

dahon speed FD clamp is 40.1~40.3mm, so close enough.

since the seat tube is slightly behind the BB, it might have an issue with getting the FD into the optimal position.

another problem is having a proper cable stop and cable that can be routed to make that bend. from the BB to somewhere up top.

you'll just have to pioneer it and find out if no one else has done it.

Got the same problem. What about the front der`s that is atached to some sort of bracket held by the "lockring" of the BB? Think you often find them on cheapo MTB and hybrids, and not for the big sized crank wheels that is used on folders. Been thinking of this for some time. should be a great solution for folders I think!

never seen it, do you have a pic?

never seen it, do you have a pic?

in line with the question above, and not to move away from the OP, i am also trying to put a FD on my dahon. has anyone tried the braze on with 34.9 mm clamp ? will it work for me also. cmcanulty - pls advise me also if you were able to do this. pics would be nice, just in case you have luck in doing this. as you know up until now i haven't been able to add a FD on my dahon. i was able to put my double chainring crank (52/39T) with a hallowtech II BB but no FD yet.

thanks,
vic

34.9mm won't work with dahon as it uses 40.1mm. the seat post is 34mm OD however.

you just have to get a caliper measuring tool or similar to find out what you have.
as I understand it, the older dahons have something else, but all the recent ones are quite similar.
http://www.bikeforums.net/showpost.php?p=9022483&postcount=10

I am thinking I need to add a tube to position it correctly, I have been dragging my feet on this as I am so unsure of best way even though I do lots of rebuilding.

Looks like I must tae a picture or two tomorrow.

34.9mm won't work with dahon as it uses 40.1mm. the seat post is 34mm OD however.

you just have to get a caliper measuring tool or similar to find out what you have.
as I understand it, the older dahons have something else, but all the recent ones are quite similar.
http://www.bikeforums.net/showpost.php?p=9022483&postcount=10

i did measure it and it's coming out to be 38.1mm, now would the 4mm difference be a deal breaker ??? or can i still force it and use 34.8 FD clamp ?

34.8mm clamp won't fit 38.1mm. 0.2mm is about the biggest difference you can use for smaller band to clamp around something larger than it's designed for.

you can however use a rubber, plastic or metal shim with the 40.1mm clamp.

Sorry I am slow. This type of bracket I found only in the size (chainring size) of MTB`s or Hybrids, I think this is a good system to use on folders, so somebody should make them in the bigger sizes!


This is how it looks:



You lock it in place with the BB:



Here it is on a bike, not so easy to see:

Sorry I am slow. This type of bracket I found only in the size (chainring size) of MTB`s or Hybrids, I think this is a good system to use on folders, so somebody should make them in the bigger sizes!


This is how it looks:

[IMG]

You lock it in place with the BB:

[IMG]

Here it is on a bike, not so easy to see:

[IMG]
that looks like a great solution. It looks like it's short for use with MTB chainring sizes, but it's hard to tell from the pics.

that looks like a great solution. It looks like it's short for use with MTB chainring sizes, but it's hard to tell from the pics.

It is small. If it was bigger it would be on my folder already, but i am thinking maybe it could be modifyed. It is found on cheap bikes.

It is small. If it was bigger it would be on my folder already, but i am thinking maybe it could be modifyed. It is found on cheap bikes.

it is really small. this is what my LBS told me to use on my folder. it's too much work just to install it and you need so much elbow grease. i decided to make a pass on his recommendation. if i were you i wouldn't even consider using this on your folder. the only viable solution is to get the adaptor from thor.

thanks,
vic

it is really small. this is what my LBS told me to use on my folder. it's too much work just to install it and you need so much elbow grease. i decided to make a pass on his recommendation. if i were you i wouldn't even consider using this on your folder. the only viable solution is to get the adaptor from thor.

thanks,
vic

No adaptor from Thor (or anybody else) is going to fit on my folder. Not at all worryed about the work, just the size- or the mod.

No adaptor from Thor (or anybody else) is going to fit on my folder. Not at all worryed about the work, just the size- or the mod.

have you checked with thor ? send him an email as i recall from the previous post that they were able to fit thor's clamp to an NS. anyway the one on the picture is what my LBS sold me for $10. but i returned it as i am worried about the work. you could try it though and do let me know if it works. i ordered a suntour with 34.8 clamp size and figure this might be an easy adjustment and i will experiment if i can do it. otherwise it will be a cheap experiment as i am getting the suntour FD for about $5.

thanks,
vic

the thor clamp will fit with a shim.

The bike I call a folder is actually a detatchable. The two parts is joined where the front der should have been and therefor there is absolutely no way for my two (similar) bikes. I am sure the solution you suggest, with or without shim is great for many folders but not mine.

This is how it looks. Different bike but same system.



The part abowe the BB shell, under the "joint" is much smaller than it looks in this picture.

well, in that case there is SRAM dual drive or hammer schmidt. Although, I don't think the hammer schmidt works too well with 16" and 20" wheels.