Random Tandem

It’s been a roller coaster week. A full cable refit to Graham’s recently refinished mid 90’s Timberline concluded my test of those Super B TB-WC30 Pro Cable Cutters https://www.sevendaycyclist.com/super-b-tb-wc30-pro-cable-cutters. I was also rather excited by a freshly blasted racing tandem that prepped and plugged, ready for a zinc rich epoxy base coat.

Turns out it’s an early 1950’s Rory O’Brien. Part of the refurb involved removing braze-ons, including the bottle bosses, which struck me as a curious move-even if the machine was being used for short-distance TTs.  

While the forks follow the traditional lugged and brazed construction, the frame is beautifully fillet brazed. Some would say this was an obvious choice for a pared to the essentials race rocket for two, saving precious grams and making it harder to disguise poor workmanship.

Urban myth, on both counts; though not commonly practiced during this frame’s era, TIG welding still translates into a lighter build, saving approximately 340g on a typical tandem frameset.

Fillet brazing is a process where brass is built up in layers, forming a very strong, uniform bond.  A frame constructed this way stands a better chance of survival following a collision with a tree, or parked car.

Talking of cars, anything other than fusion welding will signal MOT failure but a decent coachbuilder could successfully join two old school Jaguars together without any fear of failure. Motorcycle frames were also fabricated using this method.  

Being more labour intensive, there’s a cost implication but less competent/experienced builders can still get away with sloppy work. Done properly, large, smooth even fillets are all you’ll see. Be wary of overbite (where the tube has been filed at the fillet). This creates a stress point, which can result in premature and potentially fatal frame failure.  

John Moss has been focusing upon getting the Mango’s Di2 and Alfine hub combo harmonious but a conversation about machine shops and this Chinese made titanium seat post ignited his curiosity. Staying wit the Di2, he’s been having problems getting the shifters to communicate as he’d hoped with the 11spd Alfine hub. John’s career as a highly skilled technician means he loves to diagnose, fault find and continuously improve equipment.

I explained I had a 27.2 Ti post doing something nothing close to nothing and was toying with the idea of having it machined down to 26.0. This could then replace the Univega’s otherwise likeable BBB skyscraper. After some calculations and precision measurements, he calculated with a carbide tip, he could shave 136mm from the bottom, thus it would slide securely into the tubby tourer’s seat tube. Modern social history, human geography and industrial decline are subjects that have always fascinated me. Most cities have their no-go districts, or at least those with ill-repute.

Hillfields in Coventry has an unenviable reputation for being the city’s red-light district. Levels of deprivation are high, just as some inner London Boroughs including Hackney (despite the latter’s superficial gentrification, some might say, socio-economic cleansing).

However, it’s renown for being the region’s red-light area, drugs and associated criminal activity being consequently rife. I had always presumed this had been a relatively recent phenomenon, a’la Dagenham intensifying when the car factories and similar business left.

Anecdotally John and several other reliable sources refute my hypothesis. I’ve heard tales from the 1950s of organised criminal activity, including protection rackets, money laundering and of course, drugs. During the 1950s a smartly dressed young man walked into a Café’ and was greeted with smiles and warm acknowledgement.

A few minutes later, a woman running said eatery heard a scream and discovered the young man’s throat had been slit-in road daylight. She called for an ambulance and applied pressure to the wound using a clean tea-towel until paramedics arrived. The man survived.     

Conversation with Graham at Maldon Shot blasting & Powder Coating suggested painting the exposed section satin black wouldn’t be an issue either. It was decided that because of the metal’s characteristics, attempting to blast the surface (giving the paint fighting chance of staying put) was a non-starter, so he’d use an acid etch primer instead...Stay tuned…

The F Word: Frame Building Fact and Forum Folklore

Highly skilled metal working, though frame building in particular has always fascinated me. Most cyclists will share an interest in bespoke products at some level and once upon a time, towns and cities could take their pick of craftspeople.

Sadly, these days every online community has its resident “experts” some of whom couldn’t manage joined up writing, let alone differentiate lap weld from lap dance.

One commentator recently asserted Reynolds 531 is a low grade Cro-moly. Arguably superseded in sporting terms by 725, 921 et al, it still offers excellent ride characteristics and suits a wealth of applications from Audax to heavily laden touring.

Indeed, many framesets are truly a ’la carte-blended from different tube sets to deliver just the right characteristics. There are no short cuts. Any fool can blast metal together with heat understanding their relationship and translating this into competently engineered, fit-for-purpose structure requires considerable time and practice.

Contrary to popular forum folklore, the main reason for 531’s obsolescence boils down to manufacturing techniques, technology and consumer expectation. Giant’s ground breaking TCR semi/compact geometry concept divided opinion but meant production bikes fitted much better, especially those of us with a more feminine dimensions i.e. proportionally longer legs and shorter torsos.

Hence, fillet brazing became standard practice amongst custom builders, while mass production has favoured TIG for the past twenty five years. Since 531 cannot withstand fusion welding, the mixture was tweaked and 525/520 conceived.

These “lowlier” tubesets along with in-house blends of 4130 still enjoy a responsive, engaging ride quality but at a very affordable price-arguably perfect for starter race mounts, or indeed winter/training.         

“Ghost building”; batch producing framesets to shop specifications and under their name has been a popular staple for many sole traders. However, even this has been dwindling recently. Increasingly custom builders are designing and fitting frames here before commissioning fabrication to Taiwan.

Material choice is also far greater than ever before. Steel has seen meteoric revival, having fallen from favour during the 1990s but now competes alongside various grades of aluminium, carbon/composites and of course, titanium. These also require a very different skillset, not to mention tooling.

Therefore remaining competitive alongside volume producers, especially those in the Far East is almost prohibitive without outsourcing somewhere along the line.

Fifteen years back, having completed another professional qualification and feeling distinctly disillusioned within day jobs; I decided it was time to seek professional training in welding practice. Armed with some elementary, plain gauge 4130 tubing, I spent many hours under the close scrutiny of a giant scots’ toolmaker called George and Terry; a chirpy, straight talking coachbuilder.

Ultimately, while said Cro-moly boasted livelier characteristics, high-tensile steels such as Peugeot cycles’ HLE or electricians’ conjugate were of comparable weight, cost pennies and proved much easier to fusion weld.

Undesirable for frames perhaps but I was seeking to build a series of low-slung, single wheeled touring trailers with a view to small scale production. Prices cannot be levied upon creativity and skills development but attempting this as a commercial venture would be a fools’ mission given the prices of superior, mass produced imports.  

Spleen vented and KA’s fresh MOT certificate within my sweaty little palm, I’m headed up to see Peter Gabrielle at Birmingham’s LG arena…