7 Apr 2010

Gear hanger III (director's cut)






19th February 2010 . 1C, 35F! Overcast. Huge snowflakes coming  down in a blizzard to start the day. Everything is dripping and dripping wet. 

Decided to look at the steering and the awful chain slip on the big chainring. Despite being loose the steering is a bit lumpy. I may need to strip it down and have a look at the ball races. But not today.  

The lack of chain wrap was more serious and demanded immediate attention. A gear hanger had come with the Higgins. I had also bought a Trykit gear hanger from Geoff Booker for the Longstaff conversion. After some early trials with both gear hangers I had been running the Trykit hanger on the Higgins. Though I was never very happy about the way it pushed the gear changer pivot so far back relative to the block. Even though  its elegant design had brought the changer pivot point high the rear setting of the hanger pivot made for rather slow and clumsy gear changes. 

The original trike hanger brought the changer immediately below the block but pushed it way down by about 2.5" from the axle centre due to an unnecessarily low pivot point. Which made for even worse gear changes! So neither hanger offered an optimum changer pivot position compared to all of my road bikes with brazed-on gear hangers. One inch down and immediately below the back axle is the standard expected by the rear gear changer pivot on a road bike. Later indexed gear bikes have a more rearward hanger. I only discovered this later.

Older, rear, road drop-outs with threaded gear hanger pivot hole and stop for gear changer adjusting screw.

The clever Trykit gear hanger from the Trykit website.


I sought a simple solution which would bring the Trykit hanger forwards to just below the axle without losing its closeness to the axle height. In practice this proved remarkably easy. I simply straightened out a standard, chromed steel, front lamp bracket with a hammer and anvil to obtain my raw materials. I sawed off (and discarded) the upright lamp holder section. Then drilled another hole about an inch away from the original fixing hole on the remaining piece. A tidy up with a file and a suitably short bolt (and nut) later and the Trykit hanger pivot hole was ideally placed immediately below the trike axle. Just like a proper road bike!

The shiny bit is the old-fashioned, decapitated lamp bracket made into a forward extension for the Trykit hanger on the right. Alongside is the original gear hanger which came with the Higgins trike. I have no idea as to the history or maker of this particular hanger. Both are of steel and have substantial thickness to maintain rigidity and adequate strength in use. The Trykit hanger is hardened. (as can be readily checked by trying to file it)

It would not require much skill  to make a one piece copy of the extension bracket and Trykit hanger  combination once the exact geometry needed for your trike is discovered by trail and error. It would require a suitable tap to match the fine thread of the gear changer pivot screw. The modified hanger could easily be sawn and ground, or filed, out of a suitable piece of angle iron. Or bent up from a piece of plate steel. Even the area for the fixing hole for the brazed-on boss could be widened and slotted. This would allow some lateral adjustment to bring the gear changer central to the gear block sprockets.

Once the extension was made it required a bit of fiddling to get the rear gear changer centred and straight with the block as I tightened the fixing screws. The Trykit hanger (and the original hanger which came with the trike ) both have long slots to allow crossways adjustment to match the particular gear block and changer in use. Normally the gear hanger fixing screw passes through the slot and is tightened into a brazed-on boss. This is located underneath the axle housing. My extension plate just moved the normal fixing hole position forwards by an inch or so. 


Another view of the two gear hangers. They are inverted here compared to their normal downward facing position on the trike. Trykit hanger and extension bracket on the right.

It is absolutely vital, of course, that the new extension bracket/plate never twists or comes loose. Or the bike becomes instantly unrideable. Once I am perfectly satisfied with the hanger position I will drill and rivet a pin through the Trykit hanger and the extension bracket to ensure they never get out of shape. I just hope the Trykit hanger isn't too hard to drill. I suppose I could clean both parts up and braze them together but his would probably soften the hanger.

The weather is still too poor to go out on the road to give it a try right now.  I would need a wet suit, mask and snorkel.

A picture, or two, is worth a thousand words: 

View from beneath showing how the simple extension bracket brings the Trykit hanger forwards and under the gear block. Top gear is presently blocked by the changer hitting the deep head of the fixing bolt. This was just a handy hex head screw I had of the correct size lying nearby.  Filing a chamfer on the hex head of the screw (or thinning the head) should easily solve the top gear problem. My apologies for the disgraceful state of the gear changer. Salt and filth from the roads over months of winter weather riding has really taken its toll. A drop of metal polish should soon clean things up. The Higgins needs a repaint too.

Top, rear view showing how this simple extension plate with two holes has brought the rear changer right under the sprocket block. It does not force the changer downwards or limit the lateral adjustability of the Trykit hanger. In fact the Trykit hanger is lowered slightly but only by a few millimetres because by the thickness of the extension bracket. This is not remotely critical with regards to gear changing. It started pouring with heavy, sleety snow again as I tried to capture these images. I may be able to take some better images in a while.

Here is a view from beneath showing the extension plate/bracket bolted to the gear hanger boss under the axle bearing housing. A machine screw and nut holds the slotted Trykit hanger firmly to the extension plate. One downside with the present bracket&hanger geometry is that the gear changer pivot screw is inaccessible to an Allen key once the hanger and bracket are fixed to the trike. This is very easily overcome by removing the hanger fixing screw first. It is the hanger fixing screw head which blocks access to the pivot screw.

View through the wheel showing the ideal position of the gear hanger pivot just below the sprocket block. Note the excellent chain wrap. Prior to the modification the chain fell vertically from the back of the sprocket block to the top changer pulley in the higher gears. The large chainwheel was using up the free chain length and forcing the pulley cage vertical at the same time as the gear changer body was also drawn vertical by the chain tension. The chain couldn't be lengthened or the small chainwheel became unusable due to a foolishly slack chain. I have great hopes for  the new geometry once it stops raining, sleeting, snowing, flooding, dripping and thawing simultaneously. This is the first real thaw since it snowed before Christmas. It is 35.8F now! +1C. Wow? 

A quick trial round the block in pouring rain suggested the gear change was okay but I had not completely cured the chain slip. Which suggests the chain is knackered by the road salt since nothing else has changed. Still some ice on the minor roads but ridable with care. It just hasn't been a day for cycling. Only four miles. 

20th 1C 34F. Overcast, windy 15m/s gusts. I was being blown around and slowed by the wind but the gears were working okay and I had no chain slip.  Thank goodness I chose to wear the ski goggles. My usual cycling glasses had my eyes watering copiously before I reached the bike shed.
Having carefully examined my new hanger arrangement I might try a slightly shorter extension plate. Or probably  shorten the chain slightly instead.  It is rather a long way from the top cage pulley to the sprockets at the moment. Which may be slowing gear changes. Though the gear change certainly feels more positive than it did. 

Tried a detour through the woods but the slight thaw of yesterday hadn't cleared this road at all. It's a shame because I like this road for its scenery, undulations and usual lack of traffic. It is also very useful to put me where I want to be for several further detours. Without this road a large chunk of beautiful countryside is denied to me even if I stick to main roads.

Into the deep, dark woods! Eeny-meeny-miny-mo..In which rut shall I go? It was daft to continue because it got much worse as I went on. Most of the time I was riding in the darker central stripe with two wheels on the icy tarmac and the idler wheel up on on the ice.  The track of the Higgins is six inches too wide for these conditions. The brown slush was highly unpredictable. It was hard, crunchy ice overlying thick water ice in many places! I met about one car per mile which meant I had to stop and climb over the ice ridge to the safety of the verge to let them pass safely. The nearside rut wasn't as wide as the central one and forced me to ride with one wheel up on the even rougher stuff on the verge with the trike leaning at an alarming angle. 

Look no traction! It may look like tarmac but again it was solid ice. I could neither ride nor walk on the black stuff and rapidly ground to a wheel spinning halt. Then I found it impossible to stand up when I climbed off! So I had to take to the snow just to be able to make it up the hill dragging the trike along by the scruff of the neck. 

I took a battering from the wind when I finally escaped from the woods. Despite the higher temperatures (34F, 1C) I had to wrap my face with a scarf to stop it from freezing. It was stinging terribly for a while when I reached open fields without any shelter at all. High winds and snow are forecast for the rest of the day so I may have got off lightly with an early ride. Only 10 rather slow miles so far. I might sneak out again later in the afternoon when the wind is supposed to drop slightly. The trees in the garden are thrashing about at the moment and the wind hasn't even peaked yet. I'm going to have another look at my gear hanger to see if I can improve the chain geometry. Waited as long as I could for the wind to die down and then did another 12 hilly miles pushing as hard as I could. My legs are now much stronger than my breathing capacity.

21st Sunny, breezy, 22F, -6C. Snow drifting overnight. Stripped the head bearings.  Bottom race badly pitted. It will have to be replaced.  Confirmed the number on the fork steerer tube matches the frame number and purple is the original colour.  Though a darker colour when unbleached by sunlight.  Chain stiff in places from road salt despite yet more oil. The 46T chainwheel is largely unusable due to chain slip under load. The chain will have to be replaced very soon even though there is still lots of salt about. 

Quick shopping trip before coffee. Very cold head wind coming back. Now I'm going out again to get some more miles in while the sun shines. Managed another 26 miles before lunch. All the side roads were still iced and snowed up so I was stuck on the busy main roads again. Cold head wind for the last ten miles home so should have put on more clothing to stay warm. It was silly not to put the outer fleece jacket back on. Beard solid with ice. Now -4C, 24.5F and falling again. 33miles total.

22nd Feb 2010. 36F.  Slow thaw with some minor flooding on the roads. Took a route along the coast: I told you it was cold:

The sea is frozen as far as the eye can see.


 Snow covered sea ice for several miles under a cold sky.

Frozen waves.

The minor roads are improving but only slowly. It seems almost impossible to judge the air temperature from the saddle of a bike or trike. Despite it being slightly above freezing, when I left home today, it felt bitterly cold despite my wearing two jackets.  The only subjective indication of near freezing conditions is a runny nose and a regular cough to clear my throat. Lower temperatures don't seem to have this effect. Even the ice in my beard seems to be independent of temperature. My hands and feet can be warm one day and freezing the next. Though this is usually due to wind chill when fighting a headwind. Air temperature still isn't a clear indicator of its severity. Despite riding almost every day for months through unusually cold weather I still haven't any fast rules how I should dress for the day's conditions. It is usually a case of going outside to see how cold it actually feels and how the wind is behaving.  23 miles of mostly sunshine today. 

23rd. -1C, 30F. One inch overnight snowfall. Cold northerly wind. 19 miles.

24th  Cold, gales and snow falling all day. 0 miles. 

25th 35-37F. 2-3C. Day started with wet, heavy and sticky new snow lying and a lethal ice layer over everything. Then a slow thaw with rain. Roads very wet with lots of big puddles behind ice and snow dams. It will get much worse because the drains are covered in month's old snow and ice. The fields have yet to shed their accumulated now as melt-water. Lanes still have lots of ice ridges from traffic packing  down old snow in the same tracks. Nearly fell off a couple of times when there was nowhere left to run the wheels safely while going downhill over thick, lumpy ice! Am I having fun yet? :-) 15 miles.  


26th A tropical 40F! 4C! Light winds. Thawing. Streams of melt water running along, up, down and across the roads. Quite a still, bright day so I made the most of it and did a circle of three villages for shopping before morning coffee. I was soon stripped down to shorts and jumper. Bottom bracket now knocking loudly. They're old journal bearings I put in myself when I got the Higgins. So I'll just borrow a conventional cup and cone axle set from another bike. I'll change to a used chain too until the road salt is washed away. 23miles.

27th 35F, 1C, gales and rain all day. When it stopped raining I took a chance for a late afternoon ride. The cycle lanes and minor roads are finally clearing of ice and snow but it is still banked up high either side of many roads. Green visible in the fields for the first time in months. Only 12 miles.  

28th Feb 2010. 38F 3C. There are no roads remaining impassable now. Even the sea has (mostly) returned to its normal consistency. Finished the month with a meandering 30 mile ride down to the coast and back. A headwind was building towards the end and I was getting a bit tired. 

That chap in the mirror is following me around. Amazing! He has a trike too. ;-)

IMPORTANT NOTE: All my efforts to improve the Trykit gear hanger were pointless. Had I simply replaced the salt-damaged and completely worn out chain I would have enjoyed crisp gear changes again. I was fixing a problem which simply did not exist. My reluctance to "waste"   a new chain in continuing, very poor,  road conditions was my downfall. NOT the Trykit gear hanger. As soon as I "borrowed" a usable chain from another bike all was well again. I removed the extension plate because it served no useful purpose and actually made things much worse! Three months later I am still using the usable chain. The new chain I bought is still sitting in its box.