Tube bending is something I avoid, however there are times when it is necessary. Some framebuilders do it as a feature of their work but I tend to only use bent tubes when it is necessary to solve a clearance problem as with the child’s first pedal bike. I purchased this bender for the princely sum of £90 from an Ebay retailer who I guess is based in China but had stocks in the UK. The brand may be a red herring as I suspect it is one of those tools turned out by a Chinese factory under different names. Indeed Stakesy’s have what looks to be an identical bender available on their site for £165, though they were out of stock when I ordered mine: https://www.stakesys.co.uk/tube-pipe-benders/manual-tube-benders/sta137-buzz-bench-top-manual-tube-bender.
I haven’t spent a lot of time researching tube bending but found this Youtube video series quite enlightening despite the fact it has nothing to do with bicycles: https://www.youtube.com/watch?v=Hp7JL-tsPZs
The demonstrations use a JD tube bender. Whist these are available for a little over £300 the mandrels have to be purchased separately for each different sized tube and come in at around£150 each.
The Panana tube bender is quite a heavy duty and robust lump of metal. The only bits on it that look like they may not last are the plastic rings through which you thread the tube and which initiates the point of bending on the die. As per normal I struggle for space in my workshop and had to bolt it to the floor as it has to be secured firmly and I have no bench space where I can fix it and have room to swing the lever. Even on the floor I still didn’t have enough room to complete bending a long tube so to use it to it’s full potential you really need a circular area with a diameter of 2 metres as the lever length is 95 cm. More expensive benders have a ratchet mechanism so much less swing is required and hence floor space. Also the other feature lacking on my bender is a degree scale so bending is a question of guesswork and checking. You will find the lever needs to be pushed quite a way past the point you would expect to achieve a particular degree of bend.
The bender is supplied with a series of dies and matching rollers for different diameter tubes viz: 10,12,14,16,19,22 and 25mm. Whilst in the instructions (which with mine were terrible!) it refers to the equivalent Imperial sizes, they of course are not exactly equivalent. It is frustrating, is it not, that cycle main tubes tend to be Imperial and smaller round tubes for stays etc, are in metric. The dies and rollers seem to be coated with a thick layer of paint but despite this the die channels are all oversized for each tube.
It was quite hard work to bend the 22.2 mm (7/8 in) tube, but the bender accomplished this without difficulty. The result exhibited flattening of the tube on the outer radius, this applied to the 14mm tube also. I found bending a section of 1 inch tubing virtually impossible with the bender bolted to the floor, though I eventually managed it, and would recommend fixing it at waist height to make it much easier to apply the necessary force. This is where a ratchet bender would score heavily.
I only have a Rigid tube bender to compare performance with, which only does one size of tube, in my case 10mm. The Rigid bender is clearly a better quality device and comes with a scale of degrees and has two rollers instead of one which is why it will bend to the exact degree you set on the scale with no kickback and no need to over-bend.
I was able to compare the results from the rigid and the Panana for 10mm tube, which was chromoly with 1mm wall thickness. The Rigid bender has an exact 10mm channel in the die of 6mm depth. The rollers also have channels of 10mm width and 4mm depth, which to my mind equates to a 10mm bend. The Panana Die has a diameter of 11mm and depth of 7mm, whilst the roller has a diameter of 7.5mm and depth of 2mm. Obviously as the roller channel is only 2mm deep the true diameter could be 10mm but I did not extend my investigations any further! It is evident from the pictures that the Panana die and therefore bend radius is much greater than the Rigid bender and the results demonstrate that.
I therefore feel that the Panana bender would not really be adequate to bend 10mm tube for Pannier Rack building for which a Rigid bender is ideal. Incidentally the bent section of tube using a Rigid bender is 10mm x 9mm, whereas with the Panana it is 10.5mm x 9.5mm, i.e. the Panana bender squashes the tube more.
I tried bending a section of 1 inch tube (25.4mm). The die is 25mm but actually has a diameter of 25.4mm and depth of 16mm. The roller has a diameter of 22mm and depth of 8mm. Not sure what the true diameter would be for 12.7mm depth (i.e the tube radius) but the result of the bend below suggests it is undersized.
The stretch mark in the last picture is typical of the start of the actual bend. As you can see this tube kinked and flattened quite considerably, the bend measuring 26.7mm x 22.4mm. The squashing occurred as I rolled the bender over the end of the tube, not good!
The Panana is for bending all kinds of metal tubes and pipes from 10mm to 25mm and 3/8 inch to 1 inch. The dies don’t seem to be very precise to my mind, perhaps for this reason. The bends produced can be noticeably flattened and I feel 1 inch tubing in particular may not be satisfactorily bent. The bend radius (centre line radius) is on the large size compared with the more expensive benders which often have a selection of dies for different radii; though of course in some cases a large centre line radius is preferable. The bender is supposed to handle up to 2mm wall thickness in mild steel whilst I used 0.8 mm wall Columbus Gara. It seems possible the thinner tubing gives the less satisfactory results, though after seeing the videos posted by Gareth Lewis of Cargo Cycles below it looks like thicker tubing doesn’t fare any better. Ideally I need a decent bender.