14 Jun 2014

The Trykit makes a comeback!

My Trykit had been back to the UK for repairs. The silver brazing attaching the axle to the chainstays had cracked. Most likely because the braze has not fully penetrated the joints. This was probably due to too close a fit between the tubes. Unless there is a small gap between the parts to be joined the liquefied braze cannot flow inside the smaller tube. The majority of the joint strength comes from the capillary attraction wetting the joint both inside and out of the filleted tube.

The brazed joints had looked fine on the outside but after a year of daily use, ferrying shopping, small cracks had appeared underneath the axle in the silver braze. No doubt the problem was further exacerbated by the extremely thin, R931 stainless steel  tubing. After discussing the problem with Geoff he suggested I pack the trike well and return it to him for repair at his expense.

It was agreed that he would fit the extra reinforcing bars which he normally uses for trike conversions. And those trikes be builds with rear brakes. These extra tubes would further stiffen the axle and reduce any tendency for the centre of the axle to bend under load and from road shocks. Particularly when heavily loaded with shopping on typically poor road surfaces. He assured me that only my own trike had suffered from this brazing fault.

Reynolds stainless steel tubing is still a relatively rare material in bicycle manufacture. Most bespoke bicycle builders have used TIG welding with R931/953. Silver brazing is the other option and leaves the joints pale enough to remain attractive when exposed. (i.e. without a normal coat of paint)

It was only my irregular cleaning of the bare joints, with ScotchBrite abrasive fibre, which allowed me to see the hairline cracks in the braze. There was probably never any risk of the axle actually falling off without warning. Though I do admit it did make me feel rather insecure every time a Euro juggernaut overtook me! A very experienced local frame builder had tried to repair the first crack, with more silver solder, but it had cracked again later.

Geoff examined the joints carefully as he removed the axle back at his workshop and confirmed the lack of braze penetration. He would ensure all future joints were specially prepared to achieve adequate penetration of the braze. TIG welding was also a future option but would demand very high levels of skill to be cosmetically acceptable on a hand built cycle. Such skills require considerable practice and no doubt some manual dexterity.

Geoff kindly tidied up my trike while it was in his workshop. He replaced the scruffy, vinyl lettering on the down tubes with beautifully accomplished bead blasted signatures [using stencils] instead. The same went for the 2WD label on the axle casing. The effect is both subtle and most attractive. Changing from silver to dark in different lights. I'm afraid this image does not do it real justice but it is rather hard to capture well.

He also made me a stainless steel rack (or carrier) and brazed the necessary screw bosses onto the seat stays. Racks and bags are a subject in themselves. So I have discussed them in detail in the next post.

Needless to say I am delighted to have my Trykit trike back on the road. The Trykit completely eclipses the 60-year old Higgins in every respect. I was hesitant to mention the brazing problems on my blog but Geoff insisted I tell the truth. He wanted to assure customers that he stands by his work and will make every effort to put right any problems.

Stainless steel is certainly not an easy material to work with. Particularly when it is so thin. I would still order another stainless steel trike from Geoff without the slightest hesitation. With his willingness to listen to the customer and correct any problems, his skills in producing lightweight trikes will be further honed over time. The real surprise is how many trike components he does make himself and how little he charges for his time. I don't think it would be an exaggeration to say that his inventiveness, his remarkable skills and willingness to experiment with different frame materials, easily exceeds the efforts of all previous trike makers. 

Click on any image for an enlargement.

No comments:

Post a Comment