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Old 05-07-08, 11:08 AM   #1
RelapseBike
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Wheel and Gearing setup for R20

After a brief affair with a cheap HON folder, I am now the owner of a Raligh Twenty; or will if it ever arrives. I want to build a relatively speedy commuter/shopper/late night booty call transportation. It also has to be something with which I can pack up and skip town. I want to do it right the first time, taking hills, and long rides I may only occasionaly encounter into consideration. I am also trying to do it with as many used parts (to match my heart). Here are my wheel/gear considerations.

OPTION 1:
Buy some light 451's, skinnyish tires, and a five-9 speed
Shimano cassette. My concern is that the wheels will not support grocery shopping, as well as system maintenance.

OPTION 2
Buy a set of 24" wheels (24x 2.125) with a Nexus Inter-3 hub, try to stretch skinnier tires and tubes over them, and then run a double/triple chain ring with front derailleur.

Option 3
My cyclist roommate has a set of 26's with 1 3/8" street tires and a 9 speed cassette.

Which way sounds best for my needs? If it matters, I'm 5' 7.5", and 150lbs.

What size chain ring should I use?

What length crank arms?

I know I will probably have to have the rear spread a little, maybe modify the head tube and/or new fork, perhaps some welding of derailleur hangers, rear brake bracket work (although the 24" option comes with coaster brake, so I'd only run a front caliper) and add some lighter parts. I want to use standard parts, so I think I'll need to have the bottom bracket rethreaded.

I also want to go with drop bars and STI Shifters.

Am I asking too much (at least too many questions)? Do I know what I am talking about in he first place? I know y'all do, so help.

I know personal preference will play into how I get down. However, you can bowl with a soccer ball, and run in high heels, but there are general rules as to how things are done.

Thanks-
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Old 05-07-08, 11:18 AM   #2
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Quote:
Originally Posted by RelapseBike View Post
OPTION 1:
Buy some light 451's, skinnyish tires, and a five-9 speed
Shimano cassette. My concern is that the wheels will not support grocery shopping, as well as system maintenance.
UK twenties always had 451's so it shouldn't be a problem - small wheels are darn strong and modern aero or deep v type rims are pretty bombproof whatever the width profile.


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OPTION 2
Buy a set of 24" wheels (24x 2.125) with a Nexus Inter-3 hub, try to stretch skinnier tires and tubes over them, and then run a double/triple chain ring with front derailleur.
24s are the wheel choice of the moment!
Not sure about getting rims that wide though - If you're gonna put skinny tyres on why not get skinny rims. FWIW: there are two 24" sizes in common use; 509 on youth mtbs and 520 which are used on Airnimals and a better source for more road type tyres.

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Option 3
My cyclist roommate has a set of 26's with 1 3/8" street tires and a 9 speed cassette.
Too wide. Tyres won't clear stays; Also - using a 559 (26") on the front will make the whole front rise up and give you a very 'old-style' roadster steering angle which may not be to your taste.

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What size chain ring should I use?
The bigger the wheels, the smaller the chainring you'll need to compensate. Perhaps you need to do a bit of research about gear inches - work out what you like on a 'normal' sized bike then transpose that to the wheel-size you want to work out the optimal chainring size for that setup.

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What length crank arms?
I run 170mm ones on my Twenty with 406s - they are a little low and 165s would be better. Every wheel size you go up - the crank length becomes less of an issue as the BB rises with every mm of added wheel height.

Sounds like it'll be an interesting build!
lttlpxl
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Old 05-07-08, 11:28 AM   #3
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I have a made in USSR bicycle very similar in geometry to the R20. I am using 451 mm rims in a road single speed drive train and I am very pleased with this size wheel. I am now the proud owner of two R20 frames that I am slowly transforming into "modern" bicycles. Again, I will use 451 mm rims. There are 451 mm BMX racing wheels, so I suppose they are strong enough to carry groceries

http://www.sun-ringle.com/contentpages/bmx/rims.php5

You also have 20 x 1 3/8 tyres that are wide enough to support some extra weight and at the same time skinny for confortable road riding.

http://aebike.com/page.cfm?PageID=30...ils&sku=TR2697

About crank length, I would go from 170 mm.

Last edited by caotropheus; 05-07-08 at 11:39 AM.
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Old 05-07-08, 01:29 PM   #4
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Thanks to both of you. LittlePixel, you're rides are serious. You're work and love of the Twenty puts you among the ranks of S.Brown. For your 520mm mockups, did you only use Photoshop? If so, what filters made them look so well drawn?
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Old 05-07-08, 02:47 PM   #5
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Your work and love of the Twenty puts you among the ranks of S.Brown.
Well I don't know about that but thanks for the positive words. It's nice to see so many Twenty fans on the forums these days...

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For your 520mm mockups, did you only use Photoshop? If so, what filters made them look so well drawn?
Heh... I wish there was a 'Make my Raleigh Twenty look cool' filter... but sadly not - Maybe in the upcoming CS4 version?
Seriously though - I've been a hardened user of Photoshop for about 15 years now for my day job (makes me feel old) so knocking out the odd dream-bike is sort of second nature. They're made with composits of a stripped 20 frame someone posted as an image on here a few years back, Airnimal Wheels/drivetrain/fork and other component images sourced with Google Image search.

I 'cut' them out using layer masks and then the whole thing is colourised using non-destructive colour overlays if that makes any sense? I kinda 'think' natively in Photoshop these days so it's hard to relay every exact step of the process... I welcome more virtual bikes on the forum though...

Huw
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Old 05-07-08, 07:17 PM   #6
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9 spd rear cluster will not fit.
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Old 05-08-08, 12:38 AM   #7
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Well, it would if you cold-set the back end, wouldn't it?
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Old 05-08-08, 07:32 AM   #8
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Well, it would if you cold-set the back end, wouldn't it?
No, I don't think there would be enough clearance, even if you did that, Sammyboy, you can only widen them so much.
I read awhile ago a post about someone struggling to get a 7 spd cluster to work because the chain was too close to the chainstay, so he could only use 6 gears. If it works, then count me in.....
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Old 05-08-08, 07:46 AM   #9
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There are some who will grind the chainstay. Some grind it and then weld it back in for strength (there used to be fotos of this on lil pix's R-20 Wiki site, Im not sure where it went )...
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Old 05-08-08, 09:14 AM   #10
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No, I don't think there would be enough clearance, even if you did that, Sammyboy, you can only widen them so much.
I read awhile ago a post about someone struggling to get a 7 spd cluster to work because the chain was too close to the chainstay, so he could only use 6 gears. If it works, then count me in.....
I think that was me. I didn't do the work myself, but my LBS guy can do all kinds of great stuff with a welding torch. He does custom work in the winter, when business is slow. He cut out part of the seatstay and filled it back in, good as new. He actually said that even though this method is plenty strong, in hind sight he should have recommended to me to take of the rear brace/brake mount, open up the space, and tack on a new brake mount. It would have been a more elegant solution. Since having this done, I was able to source a part that allows me to use an 8 speed casette on my SRAM 3x7 and I now can use all 24 speeds to my heart's content!

Juan
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Old 05-08-08, 10:23 AM   #11
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Make it elevated chianstay like a Chopper. Hide the stay behind a chainguard
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Old 05-08-08, 01:39 PM   #12
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Well how's bout this to add to the mix. I "found" an SA 8 speed internal attached to a near new DT VIII H. Thinking of transferring parts (hub/maybe fork, although it looks a bit short) to the R20. Is this a good idea?
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Old 05-08-08, 02:45 PM   #13
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juan,

Would you mind posting a pic of your bike because I've been thinking about the sram 3x7 as a future rebuild on a R20?
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