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-   -   Raleigh Twenty cold-set to 135 (http://www.bikeforums.net/folding-bikes/926904-raleigh-twenty-cold-set-135-a.html)

Rob_E 12-20-13 04:04 PM

Raleigh Twenty cold-set to 135
 
I'm just wondering. I had always planned on eventually putting a Sturmey-Archer 8 speed hub in there as that was the widest range IGH that would fit. But then I found a good deal on a hub with a wider range, and I'm tempted, but if it doesn't fit in the bike, or if I destroy the bike in the process, then I guess it's not really a great deal.

I asked over in Raleigh Twenty land, but there are a few Twenty riders here, too, so I thought I'd see if anyone has tried this.

rhenning 12-20-13 04:34 PM

Because the chain and seat stays are so short I wouldn't go that far. You would really have to realign the dropouts because of the sharp angle the stays would be at. If you have a frame builder/good bike shop near you I would ask their opinion and maybe even have them do it. Roger

fietsbob 12-20-13 04:51 PM

You accept a repaint? hot set would be heating the tubes to almost brazing temperature...
bend of course would be where heat softens it, it will be stiff again, cooled .

Apparently The S-A 8 can lose some left end axle parts, nuts and spacers for thinner ones
so less than 135 is required.

social suicide 12-21-13 02:05 PM

SA XRF-8 is 120mm and I think the R20 is spaced at 114 so no cold set is needed. Sixty-fiver I think has cold set his 20. From what I've read, cold set only!

Rob_E 12-21-13 02:22 PM

Yes, I know I can squeeze a Sturmey 8 speed in. I just wondered if anyone had success getting a wider hub in there.

LittlePixel 12-21-13 06:17 PM

I fitted a SRAM Spectro S7 (OLN 135 I think) in there no bother - I cold set the stays in the time-honoured Sheldon Brown way - using a length of 2x4 wood, and not a little bravery but it worked out fine.
Steel is very strong and very forgiving so don't be shy!

Despite what Rhenning is saying up there—the angle difference at the dropouts in widening the stays from 115 to 135mm will be negligible and hardly move the dropouts from their parallel positioning;
Yes - you could have a go at straightening them with a vice or molegrips to be more 'proper' with the mod, but I really don't think there's a need for this - as long as the nuts of the hub can grip onto steel then you're golden.

Fitting wider hubs can be a problem on Twentys if it's a cassette hub as often the smallest sprocket can foul the chainstay (not designed for derailleurs) but with pretty much any flavour of planetary hub there really shouldn't be any problems of clearance for the chain or sprocket.

Sixty Fiver 12-21-13 06:38 PM

The issue with the Raleigh Twenty and cold setting is that if you use a cassette the drive side seat stay will interfere with the chain as it runs on the smallest cog, the bike was never designed for this.

http://www.ravingbikefiend.com/bikep...11forrest5.JPG

I initially cold set and flattened the seat stay where it meets the dropout to eliminate this interference and then decided to rebuild the rear triangle with new stays and dropouts with a 130 spacing to handle the derailleur drive.

http://www.ravingbikefiend.com/bikep...estpowder7.JPG

http://www.ravingbikefiend.com/bikep...13forrest1.JPG

Using an IGH would not cause any issues due the chain line being centred.

Rob_E 12-21-13 06:52 PM

It's good to hear from some folks who actually tried it. I want to put an IGH in there, so I have hope that clearance won't be an issue. Did you both do this without breaking/replacing the bridges of the rear triangle? I'm trying to figure out how much I can get away with without involving a frame builder or welder. Long term I'd love to do more extensive mods (brake posts would be wonderful), but short term I want to get it at least functional on my own.

Sixty Fiver 12-21-13 10:49 PM

Quote:

Originally Posted by Rob_E (Post 16349723)
It's good to hear from some folks who actually tried it. I want to put an IGH in there, so I have hope that clearance won't be an issue. Did you both do this without breaking/replacing the bridges of the rear triangle? I'm trying to figure out how much I can get away with without involving a frame builder or welder. Long term I'd love to do more extensive mods (brake posts would be wonderful), but short term I want to get it at least functional on my own.

Cold setting is not that difficult although I say that as a frame builder and this is something that is a common part of the job.

Going from 114 to 135 is quite a change although the R20 frame's high tensile frame takes to bending quite well... alignment of the dropouts is most crucial and with the right tool only takes a few minutes.

Running the IGH will make things so much easier... with cassettes and freewheels you often have to lock out the smallest cog so that you get chain clearance... when I fattened the seat stay on my R20 this was done with heat as the frame was going to get powder coated and you can see what it looked like before with all the modifications.

If you are worried about the bridges these can be clamped to prevent the stays from bending higher up and causing any possible issue with the bridges.

Rob_E 12-21-13 11:27 PM

Quote:

Originally Posted by Sixty Fiver (Post 16350129)
If you are worried about the bridges these can be clamped to prevent the stays from bending higher up and causing any possible issue with the bridges.

I just ask because it was suggested that it might be necessary to remove and replace the bridges. If the cold setting has been done without worrying about the bridges, I may give it a try. If removing and replacing the bridges are an issue, the I'm back to finding a frame builder.

Rob_E 04-07-14 08:54 AM

1 Attachment(s)
I just came across this thread when looking for a solution to my brake problem.

I just wanted to update and say that, at least so far, this seems to have been a success. I cold-set the rear triangle to 135mm. I put in a wheel with a Nuvinci hub built into it. Been commuting on it for a week and all is well. The real test will be some longer trips I have planned in the coming months, but so far, so good.

On remaining problem is a rear brake. I thought I'd just get the roller brake version of the Nuvinci and avoid any brake compatibility issues, but with the roller brake on the hub, the wheel no longer fits. The roller brake hits the chain stay. Possibly some more bending, and then straightening of the rear dropouts would make it work, but I feel like I'm already at the limits of what I'm comfortable doing to this frame, so I'll be looking at other brake options for the time.

But so far getting the modern hub into this old frame has been a success.

http://bikeforums.net/attachment.php...hmentid=373300

Sixty Fiver 04-07-14 09:47 AM

Quote:

Originally Posted by Rob_E (Post 16648989)
I just came across this thread when looking for a solution to my brake problem.

I just wanted to update and say that, at least so far, this seems to have been a success. I cold-set the rear triangle to 135mm. I put in a wheel with a Nuvinci hub built into it. Been commuting on it for a week and all is well. The real test will be some longer trips I have planned in the coming months, but so far, so good.

On remaining problem is a rear brake. I thought I'd just get the roller brake version of the Nuvinci and avoid any brake compatibility issues, but with the roller brake on the hub, the wheel no longer fits. The roller brake hits the chain stay. Possibly some more bending, and then straightening of the rear dropouts would make it work, but I feel like I'm already at the limits of what I'm comfortable doing to this frame, so I'll be looking at other brake options for the time.

But so far getting the modern hub into this old frame has been a success.

http://bikeforums.net/attachment.php...hmentid=373300

This is why I decided to rebuild my P20 but then, I have the tools and skills to cut up a frame and put it back together.

The seat stays on the Twenty were never designed to accommodate a derailleur gear or a hub brake like the one on the NuVinci and are rather fat with no offset or taper.

With a derailleur gear the outermost cog sits too close to the seat stay and the chain will rub, the solution is to modify the seat stay (heat is required) or re-space to add 5 mm of clearance on the drive side... or not use the outermost cog to give proper clearance.

Adding 21mm is possible, as said one needs to make sure this does not compromise the bridges and this will put a good deal of tensile stress into the frame.

Internal gear hubs do not present the same issues with chain clearance and on a 20, an IGH makes good sense.

fietsbob 04-07-14 09:52 AM

Constrain the width at the bridges and the brazing wont be as stressed as the bending will be further back ..

Rob_E 04-07-14 09:53 AM

Yeah, chain clearance was fine. Largely because the shifting mechanism sits between the dropout and the cog, keeping the cog far enough away from dropout.

On the other side, the roller brake almost fits, but it bulges out at the brake arm, and the brake arm by necessity has to run parallel to the chainstay. Otherwise it might work.

Sixty Fiver 04-07-14 09:58 AM

Quote:

Originally Posted by Rob_E (Post 16649218)
Yeah, chain clearance was fine. Largely because the shifting mechanism sits between the dropout and the cog, keeping the cog far enough away from dropout.

On the other side, the roller brake almost fits, but it bulges out at the brake arm, and the brake arm by necessity has to run parallel to the chainstay. Otherwise it might work.

Sounds like it it needs an offset mount to compensate for the chainstay angle ?

Rob_E 04-07-14 10:26 AM

Quote:

Originally Posted by Sixty Fiver (Post 16649242)
Sounds like it it needs an offset mount to compensate for the chainstay angle ?

I don't know what you mean by an offset mount. If you mean an something to move the mounting position of the brake arm to the chainstay than I'm not sure that'll do it, but I will have to look closer. Alternative brakes for an R20 with 406 wheels seem hard to come by, figuring out the roller brake would really be nice.

The main body of the roller brake has a bulge that's wide enough to hit the chainstay if I rotate the brake arm to anywhere near the chainstay. If I were to position the brake arm straight down, at a 90 degree angle to the chainstay, it might work, but attaching it to chainstay could be problematic, as could getting the brake line enter the brake line from below the bike.

It may be possible to make it work. It might even be that a different roller brake would work. But last night when I was trying to get it set up for the morning commute, it was frustrating me, and I gave up so that I could have the bike together and functional this morning. I may give it another shot and try to imagine a solution, but I'm afraid I'll trying to figure out a drop bolt/caliper brake solution if I want rear brakes.


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