Raleigh Twenty: Fork / Stem ponderances

So, my original plan has kind’ve failed.  The threadless headset I bought is just too tall, meaning one of the locknuts won’t fit.  Further investigation indicates that people usually saw off part of the head tube to make this kind of alteration work.  That’s not something I’m prepared to do!

I’m almost glad, however, as the alternative is to replace the entire fork and put on a new threaded headset and a proper quill stem. It’ll look way better than the original fork, and apparently it’ll improve handling a bit.  Also, I won’t have to file down the dropouts in order to get the front wheel to fit.  Unfortunately, the only source I’ve found for a replacement fork has currently sold out, so I’ve been investigating alternatives.  There’s lots, so why not share what I’ve found?

Option 1: Replace the headset only.
This was my original plan, as it’s cheap!  Merely buy a 1″ threadless headset that has the lowest profile top race that you can find.  The original nylon headset (if you can call it that) is only about 6mm tall, so I’m not sure if it’s actually possible to buy a headset that small.  If it’s much larger, then you might have to live without one of your locknuts, or you might have to shorten the head tube by cutting part of it off.

I had an extra thought about the dangers of removing a locknut..  are two locknuts really necessary on a Raleigh Twenty? The fork/headset configuration bears more resemblance to a threadless setup than a threaded setup, in that the QR adjuster clamps onto the fork in the same way as a threadless stem clamps onto a fork.  The difference is that there’s nowhere to put a star nut thingy on an R20, so there are locknuts instead.  Also, I found this on Sheldon Brown’s website, where he uses a seat clamp to hold a fork in place.  It’s probably not good enough for most bikes, but for a bike that’s only going to be used now and again, for short distances, going very slowly, and on fairly flat surfaces, then it seems like quite a viable solution!  I think I’d upgrade the R20 QR to a seat clamp, however.

edit: I suppose the QR could be omitted, rather than a locknut, which would mean buying a new stem.  You have to be careful using quill stems in the original fork, because if the stem wedge applies pressure to the slotted area, it can split the fork!

Pros: Cheap! Get to keep adjustability of handlebars.
Cons: Might need to shorten the head tube, otherwise locknut dubiousness. Have to use the original fork.

Option 2: Replace the fork, headset, and stem.
It is possible to buy forks that have steerer tubes that’re even longer than the original R20 fork, in rigid or suspension styles. Something to do with recumbents using them.  Unless it’s an actual R20 fork, the thread on the forks are standard, so any threaded 1″ headset will fit.  A new fork will mean that the stem will also need replacing, as the fork won’t have a slot cut out of it to allow the stem to be gripped by the quick release.  The steerer tube might need cutting if it’s too long (not as scary as cutting the frame itself).

Pros: New, better made fork, with modern dropout spacing. You might even find one with brazed-on brake fittings or suspension!
Cons: Potentially quite expensive (estimate for my plan is £40). Will probably need to cut the steerer. Un-adjustable stem height.

Option 3: Use a short fork with a steerer extender, new headset, and new stem.
As forks with long steerers are a bit pricey, you could use a normal fork with a steerer extender, if you can find one.  Most extenders that are on sale are threadless extenders, which makes things a little weird, but there are 1″ quill extenders, that basically bolt on a bit more tube on top of the steerer using a quill wedge.  The ones on ebay are called handlebar risers, and add 100mm, which is enough to make a standard BMX fork usable. They’re not threaded, though, so I’m not sure how useful they’ll actually be.

Pros: Can use any 20″ fork you want
Cons: Same as option 2, plus I’m not sure how useful a riser is.

After thinking about the locknuts, I think I’ll go back to the original plan.  I’m still really tempted to replace the fork completely (mainly because BMX forks are so much cooler!), but it’s £40 that I don’t really have at the moment..  £23 for the fork, at least £8 for the stem, £10-ish for a headset.  Compare that to the £4 I spent on the headset, and £10 tops for a BMX seat clamp.

ooh, and I really need to get around to measuring the head tube length and steerer length!  😛

UPDATE: Steerer and head tube measured!  235mm and 186mm, respectively. I couldn’t find my proper steel rule, so I had to use a giant wobbly one, so give or take a mm or two.   I’ll add them to the measurements on the previous post.


Raleigh Twenty: That headset

Have you ever pondered doing something, decided to look it up online, and found lots of semi-answers that don’t give you the full picture?  Yeah, me too!  Annoying, isn’t it?

Bicycle articles are particularly bad, because they almost always assume that you have the bike in front of you, and that you know what you’re doing.  I don’t!  I’m at work, and my bike knowledge may be above average, but I’m still pretty noobish.

So, when trying to find out how to upgrade the nylon headset of the Raleigh Twenty, I was getting annoyed by not knowing the full story.  After doing some measurements last night, and having a proper look at what everything does, maybe I can redress the balance myself!  🙂

Firstly, I’d better describe how it all works.  It’s not quite the same as a normal fork and stem, because it has a quick release for the stem.  The fork steerer has a long slot cut out of it, which allows it to be compressed by the QR, just like how a seat tube is compressed by a seat clamp.  The stem, which is just a basic tube, can therefore be gripped in the same way as a seat post.  The steerer is extra long, and the QR fits under the locknuts.  It’s quite a nice arrangement, really!

Here be the measurements, from top to bottom. Measuring tubes can be a bit tricky, so give or take a millimeter:

  • Handlebar OD (where it’s clamped) = 15/16″ / 23.8mm
  • Stem OD = 7/8″ / 22mm
  • Stem height = 9 7/8″ / 250mm (no minimum insert line, because it’s supposed to be tethered to the front brake with a rigid wire)
  • Upper locknut height = 3/8″ / 9.6mm
  • Lower locknut height = 3/32″ / 8mm
  • Stem QR height = 5/8″ / 16.1mm
  • Lamp clamp height = 1/16″ / 2mm
  • Nylon bush protective cap height = 1/32″ / 1mm
  • Nylon bush lip height = 3/32″ / 3mm
  • Nylon bush ID = 1″ / 25.4mm
  • Nylon bush OD = 1 1/8″ / 29.8mm
  • Fork steerer height (inc thread) = 9 3/16″ / 235mm
  • Fork thread height = 3/4″ / 19mm (Raleigh 26TPI thread)
  • Fork steerer OD = 1″ / 25.4mm
  • Fork steerer ID = 7/8″ / 22mm
  • Head tube ID = 1 1/8″ / 30mm
  • Head tube OD = 1 5/16″ / 33.1mm
  • Head tube height = 7 3/32″ / 186mm

I was only using a digital calliper, which wasn’t long enough to measure the head tube height, and I haven’t got any measurements regarding the lower race or crown race.  My measurements were coming out all over the place on those, so thought it best not to include them.  If I ever decide to replace the fork (quite likely!), I’ll get them measured.

My intention is to replace the nylon bushing with the top half of a 1″ threadless headset.  There’s no issues with diameters, but there is an issue with heights.  The bushing, including cap, is only 4mm tall, and you can also add the 2mm from the pointless lamp holder, but the exposed top of most threadless headsets is taller than that. For example; the threadless headset that I randomly bought is about 10mm tall, which would mean the upper locknut would be only half attached. :s

However, all is not lost!  It just so happens that BMX seat clamps have a diameter of 25.4mm – the same diameter as the steerer tube.  That means I could potentially ditch the tall original QR and replace it with a much shorter seat QR and possibly a couple of spacers. The only problem is knowing how tall the BMX clamps are, as that measurement is never mentioned, and they come in a range of heights.  I might have to brave the BMX section of Evans, and have a look for myself!  😮

UPDATE: Evans have a rubbish BMX section! Also, it turns out that only old 80s seat clamps are suitable for the job.  The old standard was 22.2mm seat tubes, whereas they’re now 25.4mm.  It makes searching for a clamp rather tricky.  The old clamps are all quite chunky, though, and most are actually taller than the existing QR.  gah!

I also measured the seat tube, but it rather illustrates how I can get things wrong with the callipers.  I measured 28mm ID and 32mm OD, but apparently all Raleigh Twenties have a 28.6mm seatpost.  Hmph!  The seat post is 315mm high (top to bottom) .

UPDATE 17/10/13: Added a few more measurements.

Raleigh Twenty update

Some parts have arrived for the Raleigh Twenty, and I thought I’d share what the bike might be turning into.  First off, here’s a pic of the frame and crankset, all by itself:

So far, so slightly rusty!  I’m not sure what’s going on with the crank arm alignment.  Hopefully it’s just a case of loose cotter pins, rather than badly aligned and impossible to remove cotter pins.  😛

The shopping list so far is:

  • 20″ Acorn mag wheels (cream), inc coaster brake and 18T freewheel.
  • Inner tubes
  • Primo V-Monster tyres
  • Tange threadless headset (hopefully using the top half to replace the nylon bushing)
  • Eastern Bikes clear black pedals

I’m still waiting for the pedals and tyres, but here’s what it sort-of looks like so far (ignore the mess!):

So, it’s kind’ve a foldable BMX!  🙂

This weekend, I’ll be trying to strip the paint, as there’s too much bubbling to leave it on.  I have no idea what colour to paint it with.. I was tempted to resurrect the rat look project (rust(s)hopper!), but rusty shopper bikes are hardly a rarity, and it’ll probably just look like I’ve really let it slip.  😦

Raleigh Twenty: The Plan!

Well, the Raleigh Twenty is a proper project, and no mistake! There is much to do. As it’s so quirky, I feel that I should keep up the updates regarding what I do to it. Maybe someone on the interweb will find my dabbling useful!

Normally, I like to take loads of photos of a bike that I’ve just bought. It helps me plan anything that I might want to change, and reminds me of what used to be on it. This time, however, I got straight down to taking it apart, and I didn’t stop to take photos. I was on a mission to get as much off of the bike as possible! Why? Well, despite having smaller wheels and having less tubing than any of my other bikes, it is by far the heaviest bike that I now own, and I wanted to find out where all the weight was coming from, and also make sure that I hadn’t just bought a complete and utter dud.

The weird thing about the weight was that it appeared to be mostly distributed toward the back of the bike, whereas I would’ve thought the chunky main tube and hinge would’ve been the center of the weight. It turned out that this was due to the rear wheel, with it’s Sturmey Archer 3 speed hub and steel rims. I reckon the wheel must weigh about 2kg! Everything else was fairly lightweight. The handlebar, despite being a massive steel 70’s thing, was lighter than the original handlebar from the ALX89! One thing I haven’t checked, that I think will also be contributing a lot of weight, is the steel crankset. It’s about the only thing that hasn’t been removed, due to the need for hammering.

The bike itself seems to be in good condition. There’s some missing paint here and there, and some small bits of rust, but overall it’s pretty good. This is, however, completely irrelevant, as I intend to replace almost every single part!

So, onto the plan..

The frame
The paintwork is a bit ratty, and the blue colour isn’t great. The metallic blue is mottled, so it looks like it’s been painted with hammerite. I don’t think it is hammerite, as the decals are all original, but I figure that if it already looks hammerited, then I may as well make it actually hammerited, but in a nicer shade. 🙂

The wheels
The wheels are currently 20 x 1 3/8 (451), and made entirely of steel. 451 tyres are expensive, and new wheels are hard to get hold of, so I’m not replacing them with 451s – I’m replacing them them with 20 x 1.75 (406) BMX wheels. Despite both claiming to be 20″ wheels, neither are, and the BMX wheels are smaller enough to cause brake reach issues. I’ll come to that in a bit.

Due to the weight of the SA hub, the bike will be singlespeed. That’ll also reduce cabling, which is a bit messy on the Twenty.

I’m unsure about what tyres to fit. I’m hoping I can find a way to get 20×2.2 tyres on it.

The brakes
I’ve got a couple of options with the brakes.. I can keep the original calliper brakes, and make some drop bolts so that they can reach the new 406 rims, or I can try to find a kit that’ll allow me to fit V or cantilever brakes. Additionally, I could fit a rear wheel that has a coaster brake, which would completely remove all rear cabling. I wouldn’t consider it on a full-on commuter, but this thing is only supposed to go a few miles every now and again, so a coaster might be a neat solution!

The drivetrain
Currently, the bike has a steel cottered crankset. It’s Raleigh, so the threading is all wrong, but I already have a solution for that, leftover from when I was experimenting with the Cobra – I’ve got a square taper spindle that will fit inside a Raleigh bottom bracket and cups! That means that I can fit any crankset I like, and I can ditch the horrible cottered nonsense.

Oh, I’m also ditching the pedals, but I don’t think I’m going to spend a lot on them. I’ll probably get some plastic platform pedals. I don’t know what gearing to go for, however. As I’ll probably be ill, I guess I’ll go for something undemanding.

The seat
A new seatpost, seat clamp, and seat are definitely in order. The seatpost is apparently 28.6mm, which naturally doesn’t match any spare seatpost that I own. I have a 27.2mm seatpost somewhere, so maybe I’ll just buy a shim.

The headset
The biggest issue with the headset is that it’s really only half a headset. The bottom is normal, but the top is a greased nylon bushing with a chrome cap on top of it. The handlebar adjuster sits on top of the cap, and then there’s a couple of locknuts on top of that. The bushing adds resistance to the steering, so that you have to physically turn it to steer it. You can’t ride no-handed, or push the bike along while holding onto the seat.

If the original fork, handlebar, and stem are to be kept, the usual solution to this problem is to fit a threadless 1″ headset, but I’m tempted to replace the fork with a straight BMX-ish fork (it needs a longer steerer than any BMX, so I think the one I’m looking at is actually a recumbent fork). This will improve steering, and allow a normal threaded headset, but would mean I couldn’t use the original adjustable stem. That could be problematic, as I don’t think standard stems are made in quite the same lengths. I need to do more research! It turns out lots of people make high stems! Yay!

So, not much to do, really!