In 2017 our original Moxie redefined what was possible from a steel hardtail. By using a custom tubeset with butt profiles designed specifically for the frame, we created a long/slack/low enduro hardtail, with no external reinforcement, rated for use with a 160mm travel fork.
A custom tubeset that was both strong and relatively light was the only way we could achieve the reach and BB drop we wanted in our longer frame and make our design a reality.
The tubes are designed specifically for each frame and every tube is heat treated, including the rear triangle. Special butt profiles avoid the use of external reinforcement and the results are clean lines and super-strong joints which have not been exposed to extra heating/welding which potentially weakens the joint.
Externally it would be hard to distinguish it from any other tubing: internally, it’s a different matter.
Tubing manufacturers are able to achieve economies of scale by offering standardised tubing that’s appropriate for a wide range of applications. These applications include the aerospace industry, high-performance racing or off-road vehicles, crash-protection bars in cars and of course, bicycles. This is why the term ‘aircraft grade’ sometimes crops up with bicycle tubing.
These tubesets offer builders the characteristics and qualities that work for a wide spectrum of applications which is why additional reinforcement is sometimes necessary. However, reheating a critical area of the frame can potentially damage the tube and previous welds so, if at all possible, is avoided.
Strength in Perspective
25CrMo4 (or 4130 as it’s better known) has phenomenal strength which is why it’s such a good material choice for BMX, dirt jump or ‘hardcore’ hardtails. Reynolds 525, for example, will typically be stronger than a Grade 9 3Al//2.5 Titanium tube of the same diametre and thickness. When 4130 tubing is heat treated, its strength can be increased by more than 60%.
When similar tube specifications are considered (diametre, thickness and butt profile), a Ti frame will be lighter than a CrMo frame but the CrMo will be ‘stronger’. Heat treated CrMo (and air hardening tubesets) have as much as twice the tensile strength of Grade 9 Ti which means it’s possible to go thinner yet still be incredibly strong and potentially match the Ti frame for weight.
It’s About the Butt
If the tube walls are the appropriate thickness for their intended application and the welds are good, it’s possible to build an incredibly strong frame with this international standard CrMo – which is why it’s been used for for bicycle frames for so many years.
Butting a tube means that it can be ‘strong’ where it’s needed and weight saved in other areas where the load/stress is different. So at the joints/welds, a tube will typically be thicker and the wall thickness thinner towards the middle of the tube before thickening again at the other end.
Plain gauge tubing has the same wall thickness throughout; double-butted has two wall thicknesses; triple-butted three and so forth. Plain/straight gauge tubing can and is used for bicycle fabrication but the frame will typically be a heavier than a butted frame but again, it’s about using the correct tube for the application.
A.L.I.C.E., our adventure/gravel bike, uses a quad-butted top tube and triple-butted down tube but the down tube is also asymmetric so in section at the headtube junction, it’s thicker on the underside and thinner on the top.
Most tubing marques disallow the use of their tubing decal unless all three of it’s main tubes are from the same tubing series. Furthermore, when tubes of the same series are joined together, the strength in the welds are balanced and optimised.
A tube from another series or brand can be introduced and typically this is because the tube has a suitable butt profile, diametre or pre-cut length. When tubes are paired as the manufacturer intended, the strength at the joints (welds) are optimised. If a ‘high-end’ tube is used apart from other tubes from the same series, it might only be for economic reasons.
Artisan builders will often select tubes from multiple brands and mix-and-match them to achieve the characteristics and qualities they need, appropriate for the design.
Does Branding Matter?
Steel is made to internationally recognised standards and classified accordingly.
Carpenter, Columbus, Dedacciai, KVA, Reynolds and Tange (to name a few) have pushed the boundaries of what’s possible from steel bicycle tubing. Columbus SLX and Reynolds 531c (for example) have racing pedigree and were the materials of choice for the Tour de France bicycles of yesteryear. Frames made from these tubesets are still ‘alive’ after many years of use and are a perfect example of the strength and durability that steel has.
Columbus Spirit, Columbus Zona, Reynolds 631, Reynolds 725, Reynolds 853 and Dedacciai Zero Uno are the evolved and development versions and are commonly used with standard CrMo 4130 (and similar steels) by custom frame builders and frame-building factories today.
For some, the decal will always be a mark of honour and a thing to elicit the respect of the cognoscenti. However, a decal does not define the quality and characteristics of a frame: there’s so much more to it than that.
This is a topic that frequently pops up in conversations with the comments typically being “frames made from [brand/type] tubing feel more compliant or better than [brand/type]…”
Frame designers choose the gauge and butting of their tubes (or use straight/plain gauge tubing) for very specific reasons: strength, weight, compliance and cost are all factors that need to be considered. Availability is another.
The properties of CrMo 4130 (and the other steel super-alloys) are virtually identical so are the comparisons justified?
If both bikes are exactly the same design, have exactly the same tube gauges and butt profiles and use the same components in the build – but the tubing is a different series or brand – then there will be no noticeable differences between the ride feel.
Comparing two different bikes and equating the difference in feel to the tubing is baseless. It ignores the differences in the design and build which contribute a huge part to how the bike feels.
A Very Special Opportunity
The tubesets Pipedream Cycles use are made in small batches in the same facility that fabricates the frames. This specialist Taiwanese company is one of the best frame-builders in the industry and is also a leader in tubing technology – specifically for bicycles.
Having the capability to draw and butt tubing in-house means that tubing can be made to a specific frame design. Tubing is custom butted with some tubes also having a variable thickness in their cross-section. Longer butts and curved tubes also transfer loads from otherwise vulnerable areas, negating the need for external reinforcement which not only delivers a clean aesthetic but maintains the strength qualities of the tubing.
Our mission is to create the most aesthetically beautiful and highest performance steel and titanium bicycle frames.
Since 2005, we’ve been committed to this mission and we’re not going to compromise now.