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Old 03-25-09, 01:06 PM   #1
parcoju
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Oh the joy of 26 TPI

I have just gotten back to tinkering with my twenty after a hectic quarter of tests, papers, and all that is college life, but have once again run into the same problem I ran into months before:

the bottom bracket

I tried not one, but two spindles in the hopes that I could reuse the cups, to no avail. I tried various bearing-spinndle combinations, to no avail.

I have in my possession a Shimano UN72, but after much hammering, I think I messed up the bearings. It does not turn freely.

I thought about the Phil Wood retaining rings, but $47 + shipping is quite steep.

....

But all is not lost! I went to my LBS (one of many!) http://www.richardscyclery.com/ and they said that they could reface the bottom bracket from 76mm to 73 and retap it to 24 TPI easily. Just out of curiosity, I think I'll ask what will happen if it is refaced to 68mm......

So now I pose a question to all those who have gone before me with the Raleigh Twenty Bottom Bracket:

Retap or not to retap, that is the question!
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Old 03-25-09, 01:25 PM   #2
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Retap and face it down to 73mm. You'll be glad you did. Then you can use any old cartridge BB, and your BB problems will be over.

Or, if you're a cheapskate like me, you could modify a cartridge BB to fit with some grinding and filing:

Raleigh 20 BB
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Old 03-25-09, 01:44 PM   #3
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I went the retap and reface way, to 68mm. Works fine. I would love to put the old cranks back on though, but am unsure how to put a cottered crank on, or rather where to get a suitable one.
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Old 03-25-09, 03:13 PM   #4
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I refaced my BB down to 68 (I think i took the sides down slightly asymmetrically so that my chain line would end up nice and straight) then used a 24TPI plastic cupped cartridge unit.

I think I used a *** or Kenitx unit for a brompton unit either 113mm or 119mm long (fairly cheap).

I had to remove a little of the thread on each cup (I used a lathe but a file would work) to allow the cups to screw down to their shoulders rather than bottoming on the thread.

It's worked a treat.

Good luck!
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Old 03-25-09, 06:47 PM   #5
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I got lucky with my 1970 Moulton MK3 (made by Raleigh). The bottom bracket and cups all came apart without damage. I cleaned them and re-installed them. I even got lucky and get some very nice vintage Stronglight cottered cranks (from another BF poster) sent to me.

If I hadn't been so lucky, I would surely have re-tapped them. The availability of parts is so much better. Those old Stronglight cranks are sooooo heavy, although they look soooo good .
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Old 03-25-09, 07:51 PM   #6
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I'm in the process of rebuilding my R20s AGAIN , and I have the un72 & Phil rings set up. My problem is the spindles are way too long at 127mm so I can't get a good straight chainline for my two SA8 hubs. I've been thinking of buying expensive Phil BBs, but if you guys who have rethreaded to 24tpi believe that it is strong enough to take it, then I might go that way.
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Old 03-25-09, 08:40 PM   #7
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There are many reasons why I would much rather retap to 68mm instead of 73

-more new threads = more engagement
-ability to use shorter spindles, which leads to
-lots of chainline adjustability
-lower q factor
(I'm really digging the IRD Tange 68 x103 bottom bracket combined with 150mm Odyssey Black Widow Euros. 126mm Q-Factor! )

Reasons against:
the frame is no longer "original"

But then again, I've already respaced the fork and rear dropouts...what's rethreading the bottom bracket gonna hurt?
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Old 03-25-09, 09:46 PM   #8
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I also suggest tapping and facing down to 73 mm. I did it and works perfectly. But do not do it like me. I used force rather than brains. I took two Tange cups, and I forced them through the existing threads. Lots of oil, time and force (the lever I used to force the cups in, was about 1 meter long!) to do it. One of the cups did not go straight at the biginning and was a hell of a job to fix the all stuff right.

Now I have a second R20 frame and I will go to the LBS to do it right.
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Old 03-26-09, 12:33 PM   #9
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im on the same situation kinda stuck ...i ve got 3 UN72 of diff lenghts and the 26tpi phil wood rings and finally the phil wood tool

i tried using the phil rings but its not going smooth....too tight for some reason and i did not want to force it and im sure its riding the threads as it does almost half way but gets too tight...the original 26tpi CUPS goes in no problem the phil rings now has some very minor damage to the threads and i did not want to go further...i wanted to have someone re-thread the BB but no LBS has a 26tpi Tapping/rethreading tool.

I dread retapping it to 24tpi but let me know if your successful with LBS rethreading it i might just go that way and use the UN72 24tpi aluminum rings
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Old 03-26-09, 02:26 PM   #10
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My R20 was retapped about 3-4 years ago and has held up well to thousands of miles of use. It's a no brainer fix, unless your keeping your R20 original.
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Old 03-26-09, 04:38 PM   #11
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Originally Posted by juan162 View Post
My R20 was retapped about 3-4 years ago and has held up well to thousands of miles of use. It's a no brainer fix, unless your keeping your R20 original.
Juan162,

I use my R20 for commuting, the occassional Sat morn hammerfest and fully loaded touring, so given the extra stresses of the last two uses, do you still think re-threading it to 24tpi would stand up?
I'm not talking about pootling here.
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Old 03-26-09, 04:54 PM   #12
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Juan162,

I use my R20 for commuting, the occassional Sat morn hammerfest and fully loaded touring, so given the extra stresses of the last two uses, do you still think re-threading it to 24tpi would stand up?
I'm not talking about pootling here.
You use your R20 in a hammerfest?!!

I'd pay to see that! You are one tough sonuvabeech!
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Old 03-27-09, 05:28 AM   #13
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You use your R20 in a hammerfest?!!

I'd pay to see that! You are one tough sonuvabeech!

Well, let me clarify that..... About a year ago I took it to my Sat morn ride which is one step down from the elite riders, (who I used to ride with), It's about 80kms with moderate pace bunch riding, a 14km undulating section of helter skelter with a sprint thrown in, then a bit more rolling , followed by a hill climb attack, then add a punishing grind to another sprint, finally finishing with some spinning to warm down. On that ride I was asked two things before we started:
1. You're not bringing that thing are you?
2: Aren't those small wheels slow?
I was able to lead out in sprints, attack, chase down and work at the front on this ride, I think proving the R20 could match them gave me special powers that day

A few months ago I took it to the ride again, forgetting that the overall fitness and speed of the bunch had increased markedly........I will not go in to detail about that ride, suffice to say, I'll use it for commuting and touring for the future....
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Old 03-27-09, 09:36 AM   #14
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Juan162,

I use my R20 for commuting, the occassional Sat morn hammerfest and fully loaded touring, so given the extra stresses of the last two uses, do you still think re-threading it to 24tpi would stand up?
I'm not talking about pootling here.
Hi stevegor,

I do think it is up to the stresses you are talking about. While I don't race, I've done serious miles on it and at a pretty good pace, too. I'm not all that fast, but at my fittest I was doing 3 rides a week - 2 shorter rides between 25-30 miles and one longer at around 50 mile. Again, though not very fast, I still averaged about 16-18 mph so it's not like I was pootling around, either (not that there is anything wrong with pootling!). These rides included serious climbing where I was putting real stress on the BB as well as other parts of the bike. I haven't seen any signs of failure in my BB, nor did my LBS guy,feel like it would be a problem. It should be noted that my LBS guy is a framebuilder, does quite a bit of work on bikes for serious roadies, and was the one who actually recommended the rethreading to me.

In the end, you just have to ask yourself if you think it's worth the risk of altering your frame. To me, it's an unqualified 'yes!' To another, it may be too much of a risk.

Juan
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Old 03-27-09, 02:45 PM   #15
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Mine is no longer original... I had it retapped to 24 tpi when I installed a new crankset. Upgrading a Raleigh Twenty isn't all that hard. Sure, you can get Phil Wood but its an expensive solution when there is a cheaper solution at hand.
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Old 03-28-09, 03:29 PM   #16
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Mine is no longer original... I had it retapped to 24 tpi when I installed a new crankset. Upgrading a Raleigh Twenty isn't all that hard. Sure, you can get Phil Wood but its an expensive solution when there is a cheaper solution at hand.

Just checked up the prices for Phil BBs....$133au for the cheapest up to $350au for the best, now that is a major investment for an old R20!!
Thing is, I've already got 2 sets of Phil rings, it's just that my UN72 spindles are too long. I wonder how much re tapping to 24tpi and new BBs would cost?

Unless anyone has some UN72 bbs with shorter spindles they want to sell??
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Old 03-29-09, 11:23 PM   #17
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I would like to hear about people's experiences with refacing the BB shell to 68mm. This seems to make the most sense to me because it would give you more (new) threads of engagement in previously unused parts of the shell.

This seems like its going to be a plan A for me, as the shop owner has expressed his great confidence that this would work. He's been welding and brazing bikes together since high school and he has a whole laundry list of credentials, from teaching bicycle repair in Cal State University Long Beach, to RAAM, to even the Olympics!

http://www.richardscyclery.com/about.shtml

Yeah, I'm pretty sure this should really be a plan A.
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Old 03-30-09, 10:39 PM   #18
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Im for standard 68mm BB shell size as there are lots of BB choices available plus as you mentioned it would carve out new threads on the shell which is a plus.

I might have to take my bike there as well to get it done.

i've just recently acquired a RALEIGH crankset by SR

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Old 04-04-09, 11:34 AM   #19
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Ok...on my one other R20 non folding I did not have the same issues I had with the Phil Wood Rings threading in....so got the project done yesterday

using a UN72 probably a 68 x 115

http://farm4.static.flickr.com/3631/...5fe40806_o.jpg
http://farm4.static.flickr.com/3554/...922b4dc1_o.jpg

Last edited by EM42; 04-04-09 at 11:48 AM.
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