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Mech Ontop Of Chainstay...


David

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I seem to remember ages ago a few people coming up with crazy ideas of putting the rear mech above the chainstay so you dont bash it while riding. I think someone said there would be a problem with shifting as more chain would be wrapped around the cassette?? Basically im looknig for more info on it as I am planning on designing a street frame for my A2 DT cwk but I need to solve a problem which currently exists with frames. (I am thinking about the problem of bending mech hangers)

Any help is very much appreciated.

Thanks

Dave

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Well i don't know if its any help, but Im sure someone said that it would be difficult to use just a normal tensioner on the chain because when you pedal you tighten the chain on the top and it....does something... :S I think maybe you need to (first of all find out what the hell im going on about) solve this problem of just a normal tensioner before working out a mech :)

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When you pedal you apply all the force through the top part of the chain, creating the tension. Thats why one single speed bikes its always the bottom parts that slaps around. So because of this it wouldnt work, if it did Im sure Shimano would have done it...

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Why dont you try a dropped chainstay idea like on that onza proto?

I think the only reason they scrapped the idea was because it got silly dabs in uci comps,

which isnt going to be a problem on a street bike...

Im not intirely sure why they dropped the chainstay in the first place?? Ill look for a pic...

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or you could try a hightened chainstay like that of the new ali c/koxx design to eliminate chainstay bashage and to allow for chain removal without the need for a tool. You could then buils it and let me know whether its possible to sidehop onto the chain on it and snap the b*****d chain ;) .... been bugging me for ages :(

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It hasn't been abandoned yet.

The chief reason for dropping the stays was so that the chain tensioners could be brought "inboard" and stop them being slapped up by landing on them. It also removes any problems with the width/height/positioning of chainstays between the chain and gives a nice chain line. Other things still need to be considered but that's the way it goes...

Personally I thought the second one (which Mark has currently) looks a lot nicer than the first because of the CNC part after the bottom bracket continuing in line with the down tube.

Removing the chain without a link tool was just a side issue, not the reason it was tried in the first place.

Regarding looking for problems to solve, I'm sure everyone could supply you with one if they thought about it; there are usually things I think of while riding but which are forgotten quickly.

If you can conveniently get to Coventry you should visit the transport museum, which has a fantastic number of bicycles which might give you some inspiration. Alternatively there are some books, but they aren't usually easily found. Names if required...

The only way to put the changer on the top would be to pedal backwards (like people have said the chain needs to be in tension between chainring and sprocket). There has been one gearing method which gave you one gear when pedalling forward and another when pedalling backwards... how many gears did you need?

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