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Old 11-19-05, 11:37 AM   #1
Guy Yinon
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Front derailer on a twenty ?

Hi !
Might sound crazy, but did someone tried to install a front derailer on a Raleigh Twenty conversion ?
Thanks !
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Old 11-19-05, 11:57 AM   #2
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Cheg on this forum has one fitted that acts as simple as a chainguide to avoid chain-drops from the different feed angles from his rear derailleur; I don't think anyone else has managed it. I think the problem is mainly due to the lack of space between the top edge of the chainwheel - (esp with a big 52t or bigger) and where the top-tube hits the downtube.

Perhaps a simpler idea would be to get a SRAM dual drive which combines (I think) a seven speed cassette with a 3 speed hub to do the same sort of job without a front derailleur. Mind you - how many gears do you need! I had a seven speed SRAM Spectro hub which had as many ratios as I needed. I now ride fixed though haha so my view may be biased!

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Old 11-19-05, 12:22 PM   #3
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You can get derailleurs where the clamp is located below the pivot point for the cage as well as "e-type" derailleurs that mount without a clamp, instead using the bottom bracket (requires an e-type cartridge bottom bracket).

I suspect you could get this to work. I don't think I have any more room on my bike versus a '20 but it has a Deore derailleur with the low-clamp. See: http://www.ncf.ca/~af895/bike/big/KHS_folded_frame.jpg

Food for thought!

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Old 11-19-05, 03:09 PM   #4
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Hi Guy. Does this thread mean you got the Twenty?
This picture from Guy Bouchard's site (http://www.guybouchard.ca/twenty.htm) shows a Twenty with a double and a front der so I guess it's possible.



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Old 11-19-05, 05:16 PM   #5
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As LittlePixel said, I have a Shimano Alivio front derailer on my Twenty that is used as a chainguide. The clamp is below the pivot point so I can get it high enough to clear up to a 58 chainring. The clamp is too big for the tube but I stuck a piece of innertube under it to make up the difference. That works since it's not used for shifting and there is little side load on the derailer.

I have thought about making it a functional derailer but I can't figure out how to route the cable. Normally it would go under the bottom bracket through a guide. I could do that but it would be tough to fold and unfold without messing up the cable tension. Here is a picture of the positioning:



The SRAM 3x7 hub works very well in place of multiple chainrings but it's a bit heavy and somewhat less efficient than direct gearing when the hub is not in the 1:1 ratio. Right now the bike is set up for Florida so it has a straight 7 speed rear wheel. I don't need the range or the weight down there:



http://home.comcast.net/~cheg01/r20.html
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Old 11-19-05, 05:59 PM   #6
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Quote:
Originally Posted by cheg
I have thought about making it a functional derailer but I can't figure out how to route the cable. Normally it would go under the bottom bracket through a guide. I could do that but it would be tough to fold and unfold without messing up the cable tension.
i think i once saw someone that put the shifter on the seat post... perhaps it wasn't a twenty, but whatever the folder, it solved the cable-messing-with-the-fold problem. it'd be like a suicide shift on an old harley or something.
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Old 11-19-05, 06:52 PM   #7
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@ Littlepixel, am the proces of getting the S-ram 7 speed hub. I am getting it because i would love to make my 20 into a do (nearly) everything machine including some lightly loaded touring up inclines. How was you experience with the S-Ram? Did you like it or not? Any recommendations for the front chain ring to use with it. Is 44 teeth Ok? (I have no clue) I think i might need higher ratios as i am not a great climber at all and rarely go over 40 Kp/h. Quite some people complain about the S-Ram's first and second gear being somewhat inefficient/mushy. Do you concur? Any other insights on this hub/20 combo are greatly appreciated. Thanks!
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Old 11-20-05, 09:46 AM   #8
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v1ince... My experience with the SRAM 7 is all good.The only drag was getting my LBS to build the wheel - they didn't have short spokes nor a cutter for long ones so it took them a while to finish the job. But it was a good one when completed.

So no bad experiences with it whatsoever. It was as simple as spreading the rear triangle, popping in the wheel, putting on the chain and shifter and off I go!. No fidding with cable tensions, no dropped gears or anything. It's apparently a little loud (tick-tick) for some people but I didn't mind it one bit.

I'd say especially in the Netherlands you would probably find a 44t front wheel a bit low and find yourself not scooting along as fast as you want. The 1st and second gears are very low so you can afford to get a pretty big chainwheel upfront and still have usable low gears for hills (if you can find any ), and a nice top 'speedster' gear for downhills and flats. When I first fitted mine it had a 52t front running to a 16t rear but I found I wanted more speed and less need for lower ratios so ended up moving to 53t front and 14 rear which was a lot more suited to my needs. (This means a fabulous 37mph topout going down a local hill haha wheee!)

Basically I'm saying I think you'll find 44t might just seem a little low; Bear in mind also you can't get a rear sprocket of less than 14 on the rear (I tried a 12t - the sprocket is smaller than the casing of the hub though and means the chain will not feed into the teeth properly...)

OhI read recently on here somewhere that they are about to launch a 9speed hub... Might be worth a little wait?

(link and pic)
http://www.velovision.co.uk/cgi-bin/...l?storynum=739

Last edited by LittlePixel; 11-20-05 at 10:02 AM.
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Old 11-20-05, 12:28 PM   #9
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I think that Sram - Shimano - SA are good options but I like the idea that cassete hub is MUCH cheaper and very simple to use - My only problem is finding a rear hub with the right axle to fit the twenty rear dopouts - Any idea ? (I dont want to hassle with the dropouts if its not necessary)
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Old 11-20-05, 02:24 PM   #10
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SJSC sell this Shimano 7sp HG 36h hub with 130 OLN (which I believe can be easily re-spaced to the Twenty's rear OLN).


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Old 11-20-05, 08:27 PM   #11
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Hey Littlepixel and others. Thanks very much for those most informative replies and I candy. Drool @ the 9 speed, it does look very classy. However i am getting a very good deal on the 7 speed and i imagine the 9 speed will be a lot more costly and it remains to be seen if it will perform well/be around to stay.

@ Pixel, are you holding on to your 7 speed or going to sell it?

Cassete is cool too for sure, but for now i really want to try the S-Ram hub. I love that you can have a symmetrical bulletproof wheel and few vulnerable bits sticking out. But the day may come that i decide i need more gears or just want to try ders, not just yet though.

I do hope to do some touring on the 7 speed, maybe even into france though i suspect i will not make it up steeper mountains or even slightly steep mountains with the 7 speed. Though i may just change the ratios drastically for such a trip which then perhaps would allow me make it. I want to be a tourer (when i grow up like that late and great guy with the webpage on touring/bikes. I can't think of the name right now. But his approach to touring, simple gear, not trying to go super fast but enjoying the ride, good preperation etc.

Edit: His name is/was Ken Kifer. A true hero in my book.

Last edited by v1nce; 11-23-05 at 07:27 AM.
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Old 11-21-05, 08:24 AM   #12
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Quote:
Originally Posted by v1nce
@ Pixel, are you holding on to your 7 speed or going to sell it?
It's just in the cellar at home at the moment but I think I'm gonna keep it so I can turn my Twenty back into something more flexible should my commute change or I decide to take it on a few long rides etc...

I'm acutally tempted to build up another twenty - maybe a non folding one and do a really proper job of making it a fixie - phil wood hubs/bb; carbon forks, and disc or drum front brakes so the lovely black rims I get don't get scuffed. (hehe red paint, black rims, slicks, ferrari headbadge - this bike would RULE.

But that's all a dream right now. The one I have is sweet enough. I just want to build something new. Anyone know where I can get some Rolf wheels like on Dahon Speed bikes in the UK?
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Old 11-24-05, 09:59 AM   #13
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The 20 has a steel frame.
Why not cold-set the rear triangle to 135 OLN?
http://sheldonbrown.com/frame-spacing.html
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Old 11-27-05, 10:29 AM   #14
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Quote:
Originally Posted by LittlePixel
Anyone know where I can get some Rolf wheels like on Dahon Speed bikes in the UK?
Hi LittlePixel,

Hopefully you could find a retailer to order them, on the Dahon website, here:

http://www.dahon.co.uk/ukdealers.htm

Or you may be able to find a LBS that could get them via Fisher Outdoor, here:

http://www.fisheroutdoor.co.uk/public/index.php

Good Luck,

Andy.
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Old 11-27-05, 08:30 PM   #15
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Ta for link... Ooh look they have listings for those new Dahon Hammerhead non-folding roadbikes
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