I have owned a Nomad Mk2 for several years. My bike is configured with comfort bars and I'm my position for riding is considered "relaxed" by Thorn standards. Because of arthritis in my lower back I would like to get into a more upright or "very relaxed" riding position. What do I need to do to make that happen? Is it just a matter of installing a longer fork tube? Please advise! Thanks in advance.
You need a systematic approach. Ironically, the maximum adjustment available is also one of the cheapest in components, but is tricky in understanding and applying the engineering.
A. COMPONENTS IN COMMON IN ALL SUGGESTIONS
1. North Road handlebars. These have an upsweep in the middle and the grips are swept back towards you. These are the most ergonomic bars available. I use ones by Kalloy that come on upmarket bikes and are thrown off because the ignorant owners want something more fashionable and inevitably less ergonomic; ask at your local poncey dealers of bikes for the price of a preloved BMW.
2. A wider saddle. If you already suffer from arthritis, it had better be a Brooks. The B67 is okay for many people but the ne plus ultra of Brooks comfort is the B73, already mentioned. I'm a maniac for comfort (my whole bike is designed from the ground up for my comfort and convenience) and I use the B73. If you are very heavy or large, the B190 is wider but also less compliant than the B73. The B73 is widely regarded as the most comfortable Brooks out of the box. With this class of Brooks saddle you need a straight seat post or an adaptor to a micro-adjustable seatpost such as you already have. SJS stocks the B73.
3. A new stem. This could be as simple as an angled stem, or a different length of stem, or both, of the type you now have, or it could be a different kind of stem altogether, a so-called quill stem, or it could be some kind of an (ultra-rare) combination of both.
B. MAXING OUT A THREADLESS HEADSET SYSTEM
1. A Thorn bike generally has a relatively long steerer tube but some have been sawn off. Set the seat back as far as it will go; we're about to relax the geometry of your bike towards the ideal of 68 degrees. Sit upright on the bike, adjust the saddle upwards until your legs just bend at the knee with your foot at the bottom of the pedal's rotation. See where your hands fall naturally with your back bent very little and your elbows bent a little. That's where you want to put the handlebar grips.
2. Fit up your new saddle, seat post and North Road bars. That may be enough. See how you feel about this setup after a few rides.
3. If not enough, your next purchase is either a shorter or an upward angled stem. There are also adjustable stems; I like the hefty X-ACT ones made by Humpert so that I can fine-tune my seating position as a I grow older. There are also toolless adjustable stems, again made by Kalloy regardless of the brand name under which they're sold; I like these too, and set my ton-up record on a comfort bike by just lowering and angling the handlebars in one of these (actually the Gazelle Switch version but the principle is the same) for a racier aerodynamic...
4. If still not enough, it is time to buy a threadless steerer extender. This fits in the place of your stem on the steer tube, and the stem fits higher up on the steerer extender. Steerer extenders are available only in one relatively short size, as far as I know.
5. By now your handgrips should be between 3 and 5 inches higher, moved towards the back of the bike by at least a couple of inches and ideally several inches, and the grips will he angled for the natural fall of your hands, so that your wrists will no longer be subject to the RSI of all kinds of idiotic and damaging bars hallowed by no science, only by dumb tradition and moronic fashion. Whether all this together will do the business for you depends on what size and shape bike you started with, relative to your own shape and size, how short the steerer tube was cut, and how straight you want to sit.
C. UNLIMITED HANDLEBAR HEIGHT BY MIXING HEADSET TRADITIONS
1. Beyond what you can do with a threadless headset it doesn't get more expensive, in fact it could get cheaper, but the engineering and assembly gets trickier and if you get it wrong, you could hurt yourself seriously, as in a face plant at speed.
2. First, understand that in a threadless headset the stem the holds steerer tube in the head tube by clamping around it above the upper headset bearing. The star-fangled nut is not a structural necessity but a convenience for setting the bearing preload and positioning and tensioning the steerer tube in position while the stem is bolted on. Once the stem is bolted on the system is stable and the starfangled nut can be removed altogether if you wish. A threaded or quill headset holds the steerer tube in the headset by a threaded nut; the actual quill (i.e. stem assembly) is irrelevant to holding the steerer in place. In both systems the tension is used to preload the bearings and to position the upper bearing, in the threaded system by pressure from above by the stem, in the quill system by pulling on the steerer tube by tightening an external nut around the head tube on its thread. It is also important that the starfangled nut is a difficult thing to remove, and that considerable force is required to preset the bearing load in a threadless system without the starfangled nut. A threadless or Ahead headset system has for practical purposes only one or two fixed positions or a very limited range of adjustment, even with an adjustable stem. A quill stem stem system offers stepless adjustment over an extended range. A quill system is ideal for people with back problems or other health issues that make fitting them to the bike difficult.
3. It is possible to mix the threadless or Ahead headset/steering system and the quill steering system, and it is one way to get practically unlimited handlebar adjustment, and to make it infinitely adjustable even with a modern bike.
4. The parts required are a locking collar with the internal diameter of the steering tube outer diameter (in this case 28.6mm, a common seat tube collar) and a quill stem or quill plus stem.
5. Many seat post collars, the items most readily available in the right size for our purpose, have a ridge around the inside for positioning on the seat tube. Unless you have some means of neatly removing this ridge without causing stresses that may break the component in use with perhaps catastrophic results, this enforces using the collar on top of the steerer tube. IT IS ABSOLUTELY ESSENTIAL THAT NO PART OF THE RIDGE INSIDE THE COLLAR TOUCHES THE TOP OF THE STEERER TUBE. If it does, you haven't preloaded the headset bearings at all and expensive consequences will follow shortly. For this reason I prefer to use a twin-bolt double-height seat post collar as in the photograph below. That permits the collar to extend above the steerer for two millimetres or so, and to be used like a spacer or a stem if the starfangled nut is still in the steerer tube (see immediately below). The space on the steerer tube between the bottom of the collar and the top headset bearing is filled with spacers. A collar with no ridge, or a removed ridge, can be placed directly on the collar, with the spacers above.
6. The starfangled nut can be removed either before or after the locking collar is locked. In either case, to preset the bearing tension, it is useful to attach a stem and handlebar temporarily to give leverage for working the slop out of the system. Once the bearing pretension is set, and the locking collar locked, that is a stable steering system, albeit without a visible steering tube (covered by locking collar and spacers) and without the familiar stem and handlebar. In this scheme the stem and handlebar have no function relating to the entire front wheel system of fork, bearings, steering tube, and head tube/frame -- except to give you something to handle the steering by. (This is different from the original threadless setup in which the stem locked everything together. Those who have difficulty grasping these concepts should let their LBS do the work.)
7. Traditionally a quill stem was what it said on the box, a quill and a stem forged as a single component. Today you can also buy quills which require a separate stem, exactly like the stem in a threadless system. Unlike the threadless/Aheadset system which clamps around the steerer tube, the quill fits inside the steerer tube, and is locked in with a sliding triangular block. If it is a unitary quill stem, that's it. If it is a quill only, the stem bolts around the top of it. In either version the handlebar is attached to the stem. A standard quill stem is made with the stem parallel to the ground or at an angle either upwards or downwards. Quill stems with the stem adjustable for height and reach are also available, and I like them very much, though traditionalists abhor them as the result of bad bike fit. But bad bike fit, through age, is exactly what we're trying to adapt to! A quill only is made by BBB and several others, probably all Kalloy rebrandings. A variation on this quill has a ridge around it below where the stem will fit, and this is supposed to press down on the upper headset bearing, or spacers resting on the bearing, to preset the tension, but in this use there is only a single position and you give up the range of adjustment that distinguishes the locking collar and quill system I've outlined above. However, there is no reason you cannot use a ridged quill with a locking collar, as I have in fact done, even though I found I have enough height with the ridge resting right on the locking collar.
9. Check the torque on the lockring bolts. They are all that stand between you and considerable nuisance and cost (wrecked headset bearings) and perhaps a serious accident (no steering, perhaps even a fork coming out).
10. Fit the quill inside the steerer. The friction block must not go as far as the tube butting at the bottom of the steerer, nor must the top of the quill extend beyond the MAX line. Do not overtighten the bolt through the quill that pulls up the locking block. If yours is the quill plus loose stem type, the stem must be fitted to the quill first, before insertion, so the bolt can go through both the stem and the quill.
11. Fit the handlebar to the stem. Get the reach (adjustable stem only) and rotation (handlebar fixing bolts) of the handlebar right first, then raise and lower it to absolutely the right position for you by undoing the bolt through the stem and retightening it when you've found the right position.
12. Unless you're very experienced and confident, get your work checked by your LBS. It will take him five minutes and is well worth the few quid it will cost.
13. You must either do the routine servicing, if any, on this system yourself or explain carefully to any bike mechanic what you've done before he works on the bike. Most will not understand the mix of systems; they've been trained to believe they are entirely separate systems and
cannot be mixed. Undoing bolts without understanding what they fix in this system (which is NOT what they fix in either of the two other systems) can lead to injury and a damaged bike.
14. Here's an example:
Ignore the odd shapes of the bicycle tubes. You can see the whole bike by clicking the photo above. The headtube is British Racing Green with gold coach lining. Find the crown race cover of the headset at the bottom of the head tube, in amid the wires, and the top headset bearing at the top of the head tube. It's an S6 Cane Creek, if you know its shape (made for Humpert in Germany, so not labelled Cane Creek). Above the top headset bearing, see a stack of spacers, and above that the locking collar, which has two silver flashes (to be painted bike green -- I made this trial assembly only yesterday) and two bolts, heads facing you. Above that a thin silver ring is visible. This is the ridge around my quill, which in this case rests right on the locking collar because that is all the extra height I need (58mm above the previous installation of the same stem directly onto the top of the steerer tube). However, the locking collar locks the steering tube in the headset and preloads the bearings, so I can raise the quill anytime I want. On top of that is the locking collar, threaded end of bolt towards you, of the stem (Brain People of Switzerland n'lock stem), which is a little odd but you can ignore this; the stem just bolts to the top of the quill like it would directly to the steerer in a standard installation. Through the top of the stem, in the place of the short bolt to the starfangled nut which has been removed, is the long bolt through the quill to the triangular block which locks it into the steerer tube by friction. The handlebar is attached to the stem.
I hope this helps.
Andre Jute
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