Wednesday, 29 June 2016

Royal Enfield Chainset part 1 - Forged Cranks.

One of the things that has always bothered me about my Royal Enfield is the chainset. The early girder frame Royal Enfields have a distinctive chain ring.

A distinctive chain ring, yesterday.

My lovely wife's 1903/4 ladies girder frame has the same design albeit in a much small size, it's just that you can't see it in the enclosed chain case. I think it's got either 38 or 40 teeth but without taking off the chain case I can't easily find out. My racer has a suitably manly 52 tooth chainset of the correct design but the crank arms are mismatched, the left being a very early Williams of the same length. The right hand side has also been repaired at some point. The chain ring and the crank arm are both Royal Enfield but clearly didn't start life together. Either the ring or the crank is a replacement with the old ring being cut off and the new one welded behind it.

The weld is not a thing of beauty. 

This means that the chain line is slightly off being pushed inboard by the width of the chain ring. The cranks are also monstrously long at 7" (~178 mm) between centres, this was fashionable at the time but my knees have never thanked me for it. I much prefer cranks in the 165-170 mm range.

The solution is to keep the old cranks safe with the bike but make a new pair for riding purposes. The thought of owning a bike that I can't or don't ride is anathema to me, this is why I'm going to so much trouble making new parts for the bike. As I mentioned last time, when I emigrated from the UK about a hundred years ago, I bought everything with me, even rusty old crank sets. This was fortuitous as decent quality old parts are very hard to find in New Zealand. From the hoard I selected a pair of 6.5" (~165 mm) Williams C34 cranks. They had rust pits and not much chrome left and were the ideal donors.

20 minutes in HCl acid to remove the chrome and rust and I could begin to start work. First I need to remove the spider, this is swaged on over a toothed interface.

I milled off just enough material to allow the spider to come off 
and still allow me to room to mount the new chain ring. 

The Williams date code stamped into the cranks identified them as 1956, 50 years after the Enfield. Cranks had changed little in that half century but a few minor details needed correcting. The Williams cranks had a few weight saving bevels cut into them that the Enfield did not, these needed to be filled with weld and then re profiled back.

Weight saving bevels...

...not saving weight.

The shape of the cranks has also subtly changed over the years, earlier cranks have a much more abrupt transition between the pedal boss and the shaft and between the axle boss and the shaft. This is easier to remedy as taking off metal is always easier than putting it on again. Half an hour playing with some files and the transitions are now of the older Edwardian profile.

unmodified on the left, original in the middle and re profiled on the right...

...and the same at the pedal boss

Then the edge bevel needs to be replaced...

... to make it appear original.

At the same time, I got rid of the last of the nickel plating. Hydrochloric acid makes short work of chrome but won't touch the nickel substrate. This is very handy is you want to make something look older than it really is by exposing the nickel but means that you have to remove the nickel by other means.

The original cranks bear the legend "ENFIELD CYCLE CO LTD TOUGHENED CRANK" stamped into them.


This is quite a lot of letters to get lined up properly so I made a jig to make life easier, the idea being that I just need to worry about the spacing. The cranks on my lovely wife's Enfield read the same but have the word "THE" prepended. I have to assume that mine are correct for my year so I'll be missing off the initial "THE".

Stamping guides.

I couldn't do the Co. & Ltd. exactly as per the original. 
In years to come somebody may wonder about that.

The last stamping is the left and right hand thread around the pedal holes. Again I needed to make a little jig to guide the punches, this took a little thought to get something that worked well. I can't stand doing mono buttocked jobs, I'd much rather spend the time and do it right. But that's just me being all OCD I suppose.

Left Hand Thread.

Next week I'll make the chain ring. I've made a few chain rings before and while not difficult, they do take a bit of time if made by hand. I'm sure I could get the plate laser or water cut in a fraction of the time and if I was making more than one I'd probably do it. However including the time taken to draw up the chain ring in CAD, I'm pretty sure I could have the one ring smashed out by hand in the same time.

In other news, we've bought a rowing machine. To say that my giant son is into rowing would be like mentioning that I quite like cycling a bit. Being winter here (the solstice was just a few days ago) there is almost no rowing on the rivers at the moment. He does go and use the "ergs" at his club for the social aspect but living in the middle of nowhere makes it quite hard to do too often. Also my lovely wife and giant daughter have expressed interest from a fitness point of view. A very short conversation with my son about what to buy and a short time later we have a Concept2 Model E in our living room. Apparently, there is only one erg to get if you are serious about it. I've also been using it myself although quite timidly as my back does not like new things that involve bending too much. We shall see how it works out.

Sunday, 19 June 2016

Royal Enfield Handlebars

As mentioned last time, I've been making some handlebars. Recall that when I last rode the bike, my awesome sprinting prowess bent the handlebars at the stem.


I took a good look at the 'bars and decided that the best course of action was to do nothing to the original set and make a new pair of facsimiles. This way I can keep the original 'bars with the machine should I ever choose to sell it but still be able to ride the machine with gusto and without fear of personal injury.  The original 'bars are of a very fine gauge tubing and are extremely light. They are also rusted through from the inside and after close inspection, I'm amazed that they didn't break rather than just bent. That's one of the advantages of steel components though, sudden catastrophic failure is rare as you tend to get heaps of audible warning before a part fails.

I'm not going to make mine as lightweight as the originals, mainly because I happen to have some chromoly bends left over from the facile project that I can reuse. These are in a thicker gauge which is probably no bad thing. As I discovered when getting tubing bent previously, it is very difficult to get compound bends made in close proximity to each other, at least it is if you want high quality mandrel type bends. So I'm going to fabricate the compound shape of the bars using simple bends joined together. By playing around with the length of the straight portions I can, to a degree, control the style and shape of the final result. I've made some hollow internal lugs from 4140 chromoly, these are a tight fit inside the tubes and when welded up can be made invisible.

Internal lugs ready for assembly.

The inverted front brake lever uses a Bowden cable that runs through the handlebar, this is a very neat feature common to many Royal Enfield models of the early years of the 20th century. My wife's 1903/4 model has a very similar arrangement. The lever is sized to fit inside the thin gauge tubing not my thicker stuff. for this reason I need to chop off the last 2" of the right hand 'bar and replace it with a suitably machined adapter.

Note the last two inches of the right hand handlebar are replaced with an adapter.

I asked Pete to weld up the various parts...

...and as usual he did a wonderful job. 

After normalising the welds, it is an easy job with a file to make the welds disappear. 

I know that filing welds materially weakens the joint but my experience with the facile and the design of my internal lugs means I'm comfortable doing this. I'm confident that they won't be breaking any time soon.

I had previously made the central lug to hold both sides of the handlebars and join them to the steering tube. I got carried away when I machined it and forgot to take any photos of the process.

The steering tube is interesting for several reasons. Firstly the design, notice that the headset, original to the bike, is not a headclip but a conventional design with an adjustable race and a locking headnut,

Steering tube and wedge.

this design means that the steering tube is clamped to the fork via an expanding wedge, the design of the wedge is slightly different to later designs but the idea is exactly the same. I believe that 1906 was the only year that this headset was offered, the years either side used the more standard headclip design. I'd love to know more if anyone has any information. I have a copy of the 1907 catalogue and what I think is the 1905 catalogue but no 1906 edition. I'm lead to believe that the patent number on the steering lock is from 1906. Secondly the OD of the steering tube is not 7/8" as you would expect, 7/8" tube doesn't fit into the forks. I needed to machine the OD down to 0.865" from 0.875" to get it to slip in nicely. Also the ID needed to be thinned to suit the wedge. I didn't want to have to modify any of the original parts that bolt to the handlebars, the facsimile handlebars must be made to fit the original parts.

Next job is to clamp everything in the right places and silver solder the lug. Notice the board that everything is zip tied to, it's the same board I used when I brazed up the facile handlebars. Spooky.

Ready for silver soldering.

Finally I just need to clean up the joints a little and check for fit in the bike, I'll plate them when I plate all the other parts I'm working on at the moment.

The shape and dimensions are extremely close to the originals, I'm quite pleased with them.

Don't you just love the Edwardian racer look?

In other news, I'm having some other frames professionally painted at the moment. I'm slowly getting my list of projects down so that I can start work on the racing penny farthings. These frames have been on my list for ages and I want to get both bikes back on the road before I start. More later.

Tuesday, 24 May 2016

Cinq5 Shift:R versus Gebla Rohbox. A long term review.

It shouldn't be this hard. Really. You may recall my mention of my new bike some time ago. I had the frame custom made around my existing Rohloff hub purchased new in 1999. Since I'm a nerd, I keep detailed records of my cycling activities and I could calculate how far I've ridden it in the intervening 17 years. I could but I can't be bothered at the moment. Shifting a Rohloff on a bike with drop handlebars is not an easy problem to solve if you don't like grip shifters. This page details a myriad of ways to achieve it but the majority are the most awful and non ergonomic cludge ups I could imagine. The Rohloff was originally intended for mountain bike racing but the actual market where it excels appears to be loaded touring and expedition bikes. I think I'm unusual in that I still use mine on a mountain bike, albeit a slightly different one. I'm a roadie, always have been. There I've said it in public. With my long term back injury, I simply can't do anything too technical off road. Not because I'm technically unable but because I can't afford to come off. Where I live we have lots and lots of gravel roads and forestry tracks. Not always open year round due to fire risk but there are always really good off road rides to do. The off road stuff is actually better than the road riding with far more interesting routes and much bigger climbs. This is the reason for the new bike, it's my go anywhere bike. And since I ride the road a lot, I wanted a similar position to my road bike(s) but tweaked a little to handle off road.

Cinq5 Shift:R cable box shortly before I killed it.

You may recall that I was an early adopter of the Cinq5 Shift:R shifters for the Rohloff. I installed them and mentioned at the time that the jury was out on them. I really wanted to like them but I had reservations. In summary:


  • Ability to shift one or two gears at a time
  • Lightweight
  • Beautifully made.

  • Tricky to setup so that you could both up shift and down shift 2 gears at a time
  • Fragile
  • Shifting from the center of the bars meant that you needed to be seated to shift. Not always the case off road.
  • The tiny ratchets often slipped and failed to engage and change gear.
  • Doesn't like being fully submerged. On my bike the cable box hangs down low and I often ride through fords and rivers that cover the box. This made the slippage worse until I could clean out the box when I got home. Towards the end, I often finished rides being unable to shift any gears.
  • The shift levers require high force to change gear. This despite my best efforts using high quality cable and sensible routing. I always grind cable ends square. I have a slightly dodgy left wrist that makes it harder to change gear on that side.
  • I used the 31.8mm diameter levers. To mount these required a handlebar with a wide central section of this diameter. My 'bars are 46cm Salsa Cowbells and even with these I wasn't able to mount both levers at the same angle as the cable outers would foul each other where they exited the levers. Not a big deal, but things like that irk me.
  • The design uses the inner cable the wrong way round, the nipple is at the cable box, which means that you can't use an alternative lever without modification.

Eventually one of the tiny pawls inside the cable box simply broke (the up shift pawl) and stranded me in a high gear. Fortunately, I wasn't too far from home and I could get back easily. As a recent convert to Strava, I can say with a high degree of accuracy that the Cinq5 system only lasted 1406 km. That's pretty poor. Since the levers were new, I contacted the dealer and eventually received a replacement cable box after a 2 month wait. The levers were unmarked and in as new condition.

Cinq5 Shift:R cable box shortly after I killed it.

In the meantime, I investigated alternatives since the bike had become my favourite and I'd miss riding it. The Gebla Rohbox looked like a valid alternative, so I ordered one from SJS cycles to try out. I've used SJS sporadically over the years to buy various, otherwise hard to get, parts. The Rohbox turned up 4 days after ordering (!) not bad when you consider that I live in the middle of nowhere and that it's about as far as you can get from Somerset before you start going back again.

The Rohbox was on the bike later that same day.

In summary:


  • Very simple mechanism made from robust parts
  • Uses the inner cables the right way round. ie the nipple at the lever. This means you can use pretty much any pair of levers to change gear.
  • The maker isn't a faceless organisation but is a bike maker from Germany called Georg. I'm an early adopter of his design and my unit shipped with springs that enabled it to shift two gears at a time. These didn't work well and Georg contacted me and sent out replacement springs and two new shift cables at his cost. These transformed the feel of the unit and the single gear change now has a nice feel to it. Georg is a really good guy and is happy to stand behind his product.
  • When used with ergo levers or similar, the handlebars are very clean.
  • Very easy to set up.
  • Although not sealed, the simple, robust construction is impervious to frequent river dunkings. I opened the box after having completed the same mileage on the Rohbox as on the Cinq5 system before it broke. There appears to be zero wear on the component parts.
  • I'm tending to change gear more often with the controls at my fingertips.

  • Can only shift one gear at a time. 
  • Relatively heavy compared to the Cinq5 cable box. If heavy means robust then I'm not complaining too loudly.
  • Larger than either the Cinq5 or the original Rohloff cable box.

Initially, I set up a hybrid system using the Cinq5 levers and the Rohbox. This set up worked pretty well but still had the issues with poor ergonomics for gear changes when standing and due to my left wrist issue. I used the bike like this for a few months until I found a set of second generation Campagnolo Record Ergolevers with aluminium levers. They were only made for a couple of years in the late 90s and are much sought after. I'm pretty much allergic to carbon fibre on my bikes, I can't really explain why either, just one of those things. I've rebuilt lots of Ergolevers over the years so I know my way around them pretty well and have a draw full of spare parts. I knew that I could use the levers pretty much as is and they would work but could be better if I modified them internally. I wanted to remove everything on the thumb, downshift side of each lever. I also wanted to lock the up shift lever firmly to the cable pull. The up shift lever has a pawl that locks into a ratchet depending on which of the gears you are in, it requires a few degrees of motion before it engages and I wanted to remove this motion to improve cable pull and the feel of the gear shift. The part I made simply replaces the front ratchet and is shaped very carefully to lock the lever to the pivot. With the thumb shifter mechanism completely removed, I simply needed to make a distance spacer and use a shorter bolt.
The modifications shaved a fair bit of weight from the units.

I'd already decided to ditch the auxiliary brake levers. I seldom used them and with the
Cinq5 gear shifters going at the same time it meant my bars would become much cleaner. 

The Cinq5 system used standard gear cable with the wires running length ways. Since the Rohloff does all its indexing in the hub this is unnecessary and I decided to try using brake cable outer as it is more flexible and may lessen the force required on the cable. I can feel a slight sponginess in the system as the cable compresses but combined with the longer shift levers on the Ergolevers, the force required to change gear is reduced. I can also change gear with my hands either on the hoods or in the drops. Finally, I can now change gear when out of the saddle...

This is the best gear change I've had yet on the bike, It's not perfect and it still has some shortcomings that at present I can live with.

  • I do miss the ability to shift multiple gears at once that the grip shifter afforded. Terrain can change quickly off road and I need to be vigilant. If I pause pedalling pressure momentarily, I can rapidly shift multiple gears by pumping the ergo lever, this works well.
  • I miss the ability to see which gear I'm in. In practical terms this means that the 7/8 8/7 change can occasionally catch me out again even after owning the hub for 17 years. It also means that I can try for a lower or higher gear and discover that I'm already in it.
  • The force required to change gear varies across the range, not all gears require the same input from the shifter. In certain gears, I can't recall which ones, this means that it is occasionally possible to shift two gears instead of the single shift that you wanted. I need to stress that this is an unusual occurrence though.
  • Errr, that's it.

I have no connection to either Cinq5 or Gebla and I paid full retail prices for both units with my own money. I have since sold the brand new, warranty replacement unit from Cinq5. It was a nice try, but simply not up to the kind of riding I like to do.

In other news, I've finally started work on my 1906 Royal Enfield that I broke the last time I rode it. The handlebars are the first part to get my attention, More later.