Titanium racks

[geocycle]

I'm after a new rack as my tubus cargo has rusted badly and got holed on one corner from corrosion/abrasion.  Therefore, I'm looking to replace with stainless steel or maybe titanium to avoid more rust problems. Does anyone have any experience of titanium?  I have ortlieb bikepacker plus panniers and I would want the replacement to be compatible with these (which rules out the tubus fly range I think?).  Is Ti worth the extra cost?

[jags]

expensive ,stainless would be hard to beat i reckon

[Danneaux]

Hi geocycle,

May I offer some additional thoughts?

Ti racks are certainly nice, and will address any concerns regarding corrosion, but are still subject to abrasion over time (less of a problem 'cos the base material is non-rusting, of course, and hard). They are also expensive, and one's choices are a bit limited.  Here are some alternatives to consider...

- Stainless racks, as jags suggested. A stainless rack avoids corrosion issues, but Tubus (for one) rates them for lesser loads. One unfortunate characteristic of stainless steel is it tends to work-harden, and can become embrittled in that way. It shouldn't be much of an issue, given Tubus' nicely triangulated designs, but I did recently see a stainless rack locally that had worn through in a couple places from rack abrasion.

- It is easy to make little "hook pads" to resist abrasion from glass-filled nylon pannier hooks. I have had great luck doing this on one of my aluminum racks.  I used adhesive-backed stainless-steel tape, cut in small sections with scissors and wrapped around the rack where the hooks sit. Adhesive-backed stainless-steel tape is often marketed for automotive trim restoration or to protect the leading edges of carbon-fiber airplane propellers.  The rolls are inexpensive and contain enough tape for many years. Auto parts stores are a good source, as are suppliers of auto-body repair supplies. One example is here: http://www.jcwhitney.com/stainless-steel-tape/p2000575.jcwx Tubus include adhesive pads that work in a similar fashion, but caution they must be applied to new racks in to stick effectively and sit level. That's good advice for the stainless tape, too. Pads really do work best when applied to a new rack or one that is not badly worn.

- I've found it helpful to address the source of vibration-caused abrasion directly -- by securing my own Bikepacker Plus Ortliebs with compression straps. Ortlieb offer these, but not with a quick-release buckle. I have used Arno straps in the past, but have now settled on nylon webbing with Fastex buckles, and use only a single strap around each bag, placed vertically. The idea is not so much to compress the load but to reduce lateral sway, fore-aft movement along the rails, and the amplitude of second-order vibrations -- all of which result in hook movement. This alone has made a tremendous difference in the amount of hook-caused rack wear I've seen. I have yet to combine the stainless-steel tape with the compression straps, but I feel confident that together they would pretty well eliminate most of the problems you've experienced with rack wear, and are a lot cheaper than a Ti rack.

Best,

Dan.

[revelo]

I'm not sure why abrasion would necessarily lead to rust. I used my Thorn rear rack with Ortlieb panniers, which quickly abraded the powder paint coating down to bare metal. But no corrosion set in, probably because the racks were continually abrading the racks, so they rubbed away corrosion as soon as it formed. By contrast, the fender bolt holes, which evidently were not covered with paint and from which I foolishly removed the bolts to save weight, developed corrosion very quickly, so evidently I was using the racks in corrosion inducing conditions. (I cleaned these threads with a gun-cleaning brush, then installed greased bolts to prevent further corrosion.)

BTW, I see no reason for all these compression straps. What you really need is a second QL2 hook at the bottom, at least if using Thorn rear racks, and probably Thorn front racks as well. Thorn sells these hooks if you are in Britain, or cyclocamping.com if you in the US and don't want to pay extra shipping. See here:

[Danneaux]

I see no reason for all these compression straps. What you really need is a second QL2 hook at the bottom

Frank, I also use double stabilizer fins on both sets of my bags, much as you do. I have found they help, but still allow a substantial amount of lateral bag movement (in-out, though they greatly help limit fore-aft movement) and hook rotation, even with the proper sizing shims on the upper mounting hooks.  

I love my Ortlieb bags, but their backplate and mounting rail designs encourage hook rotation as a consequence of vertical movement.  If one puts a load in an Ortlieb pannier, closes the bag securely and mounts it to the rack, all it takes is upward pressure on the bag's bottom (pushing upward with an open hand, say) to see the mounting hooks rotate around the rack rail. This same effect happens to a degree on any rough road, and is a major cause of mounting hook-induced rack wear, and will occur even with a second stabilizer fin. The fins secure the lower portion of the pannier and do limit fore-aft and in-out motion to a greater degree than a single fin. Compression straps further limit the remaining independent movement of the bag and its contents by squashing the pannier and contents firmly against the rack, which also limits hook-caused and fin-caused rotational wear of the rack.

The stabilizer fins contribute to rack wear in a different way. Unlike the mounting hooks, the lower fins are flexible even near their bases, due to use of a different plastic formulation and shape than the upper mounting hooks. This means the lower fins can also cause abrasion and wear. An example of this sort of lower-fin wear on even a stainless rack can be seen here: http://homepage.mac.com/isaetterry/pagestoplevel/pageequipment.htm That's why I use tape pads under the lower stabilizer fins as well as compression straps to limit movement of the bags and their contents. In my experience, double stabilizer fins coupled with compression straps and pads help a great deal in limiting long-term rack wear.

By the way, the Ortlieb hook rail is a handy place to store a spare set of mounting hooks for use on any other bag; I simply make my anti-wear pads a bit longer to accommodate the extra wear points of a second set of hooks. It is surely nice to have a second set of hooks at the ready to replace any that break due to a crash or fatigue (belt-and-suspenders approach for a long tour), and storing them on the mounting rail means they don't take up any room in the panniers.  

Best,

Dan.

[Andre Jute]

TUBUS COSMO REVIEW
AFTER TWO YEARS
by Andre Jute

I've had really good luck with my rear racks. On three occasions ali racks were crumpled by carelessly driven Range Rovers, and the bikes were straight. So I've come to consider a rack a consumptible , disposable item, something like a chain or a chainring. All the same, the bright spots that my fave Basil Cardiff pannier baskets wore on the ali racks irritated me, and even the best racks these days have politically correct powder coating that just doesn't last like environment-wrecking hard duco.

A titanium rack, custom made if not found, seemed indicated. Thing is, I know quite a few techno-freak cyclists, engineers who cycle, even specialist metallurgists, and I couldn't find one with a titanium bike for any length of time who hadn't suffered a breakage. Also, from motor racing practice, where titanium space frames were once the highest state of the art, I know that those pipes and particularly their joints fatigue and part on a distressingly short cycle. Truth is, I'm amazed that ti is so widely used in aero practice.

So then I looked at stainless, and eventually bought a Tubus Cosmo. Now, tourers on adapted road bikes may have a different opinion, but I'm a utility/recreational cyclist with, beyond my own rather too corporeal presence, light requirements. Six bottles of wine for a couple of kilometres, that sort of thing. It may be that Tubus designed the Cosmo for the PBP, sacrificing utility for low weight. It's pretty narrow, it light weight also means light construction, in that I don't think those pipe walls are adequately thick to resist abrasion, and the kit comes without some of the necessary fittings, which I thought simply cheap on the part of Tubus but may be done to make their rack look good on the scales. The fitting kit, which may be necessary even on a 26" bike, is an irritating extra cost, and with the carriage, just about the price of a perfectly serviceable ali or steel rack at the LBS...

With this light weight comes a requirement for 3D triangulation if the rack is not to collapse at the first bump. So the Tubus designers ran the lower rail into the centreline of the bike at an angle towards the back. This makes it difficult to get the hooks of panniers onto the rail under the overhang of the top rail. There is also a hoop which you can attach nothing to but offers the structure further triangulation. It would have been better to design in slightly heavier wall tubing with, from the beginning, the aim that the purchaser should be able to attach something to every tube, and easily.

Though I'm not impressed with the apparent aim and design of the Tubus Cosmos, and the marketing stinks in making you pay extra for necessary distancing pieces and in not supplying all the necessary bolts and nuts, it must be said that once you have the Cosmos fitted it is rock solid, and the irritation quotient of the overhanging top rail depends on how often you take your panniers off. I keep a single Basil Cardiff pannier basket on the bike almost all the time, and on the other side occasionally fit a briefcase with hooks adapted to work with the overhanging top rail. But a tourer who wants to take his panniers off daily or more often will soon curse the Tubus designer for his incompetence or carelessness or trendiness, whatever inspired the abomination of that angled lower rail. I've learned to live with it, but, as I say, my requirements are pretty light compared to most Thorn owners'.

Tubus Cosmos:
For: Prestige, stainless so theoretically everlasting, lightweight, rock solid
Against: Poorly engineered, thin tubing will abrade fast, poorly designed with top rail overhanging lower rail making it difficult to fit and remove panniers, incomplete kit, overpriced, looks like painted ali, too sort for any big bike, old-fashioned and unnecessarily narrow design makes the Cosmos less useful than it should be, too twee and trendy for its own good

Copyright ©2012 Andre Jute

***

Further to Dan's remarks about protecting the rack from abrasion:

My fave Basil pannier baskets don't have a lower hook so I tie them on with my old webbing belts from my air force days, or with dayglo belts for extra visibility.

For protection against wire hooks and at interface points between basket mesh and rack lower down, I wrap the rack with a length of velcro in strategic places. Since I would be carrying these short lengths of velcro in the toolkit anyway, wrapping them around the rack is a saving. Not as tidy as Dan's stainless tape, but practical and proven over several years now (none of the velcro has ever worn through, making it tougher than limp modern powder-coats).

Dan's bikes always look like they're straight off the floor of a bike show, every addition he makes integrated like an OEM high$$$ extra...

The Cosmos isn't quite as toylike as it seems in this photograph; the Utopia Kranich on which I have it fitted is over 2m long, and those 60x622 balloon tyres are three-quarters of a meter high... But it is definitely on the small size for a serious touring rack.

[geocycle]

Splendid response gentlemen. Thank you for sharing your thoughts and experiences. I should point out the main source of the abrasion is from a spill I had that resulted in a corner running along the Tarmac. Corrosion followed and a hole in the tubing has manifested itself.

 I also view racks as a consumable item and use them to protect the frame against the ravages of the Sheffield stand. The tubus cargo is a very solid rack although I admit to disappointment regarding the amount of rust which is far worse than anything on my steel frame over the same period of time. I had been looking at the Cosmo but I do remove panniers several times a day so maybe the double rail design is not ideal as Andre indicates.

[Danneaux]

geocycle,

So glad the responses were helpful; I have learned from them, as always.

When you choose a replacement rack, can you let please us know what you decide on and why?

It is always helpful to see how parts age, and to see how well they hold up over time. I find myself hoping manufacturers view the Internet and user reports as a vast resource for improving the quality of their products. I can't think of a less expensive way to get a handle on product reliability so designs may be tweaked and adjusted for optimum reliability.

(Your Kranich is simply gorgeous, Andre, What an incredible bike)

All the best,

Dan.

[revelo]

I should point out the main source of the abrasion is from a spill I had that resulted in a corner running along the Tarmac. Corrosion followed and a hole in the tubing has manifested itself.

I notice no one addressed my point that corrosion didn't occur on my racks because the rubbing was always on the same spot, and thus rubbed away any corrosion that formed after the powder paint was worn away. Does this make sense or am I asking for trouble?

Not sure what to say about the photo at http://homepage.mac.com/isaetterry/pagestoplevel/pageequipment.htm. Nylon battles steel, nylon wins... And right above this is another photo and caption discussing how a stainless steel bolt breaks and is replaced by plastic cable ties, with plastic again proving to be more durable than steel. I'm not a materials science expert, but this doesn't make a lot of sense to me. I'm certainly not worried about my Thorn racks wearing out because of the Ortlieb panniers rubbing on them, nor of the 6mm stainless steel bolts that Thorn provided proving to be less durable than plastic cable ties. Maybe the Tubus racks are made of thinner tubing or maybe their stainless steel is cr*p.

[edit] the main reason for the second QL2 lower hook is not to reduce abrasion, which I consider unavoidable, but to stabilize the pannier. With a single QL2 lower hook, the side of the pannier without a hook will flop around and stress and eventually break the hook on the opposite side. There are some discussions and photos of this on the internet, I forget where. At least with the Thorn racks, with two QL2 hooks, the pannier are held very securely against the racks, to that wear-and-tear on the panniers is minimal. Yes there is some abrasion against the racks as the panniers bounce up and down, though I'm not too worried about plastic wearing through the cromoly steel used on Thorn's racks. Though maybe I'm mistaken here.

[Danneaux]

I notice no one addressed my point that corrosion didn't occur on my racks because the rubbing was always on the same spot, and thus rubbed away any corrosion that formed after the powder paint was worn away.

Andre and I did in general terms (wrt hook-rack abrasion), not specifically in regard to your observation. I will now do so directly: If corrosion doesn't occur because the hooks are always rubbing in the same spot, it may be because they are rubbing in the same spot, abrading the surface and removing rust as it occurs. It is a bare, shiny spot because powdercoat is more frangible than steel, just as Andre noted. Once the powder coat is gone...and any rust that may form is rubbed off or rubbed so frequently rust is prevented from forming...it means the hook is then rubbing directly on the steel rack tubing. That constant friction removes rust as it forms is evidence it is working away on the steel and the oxides of steel (rust). The presence or absence of rust may also depend on the climate where the racks and bicycle are used. A salty coastal climate might well cause rust to form more quickly, particularly if the bags are used infrequently.

...am I asking for trouble?

Maybe. Where there is constant friction, there is also constant wear. Eventually, that wear becomes problematic. "Eventually" is a nonspecific time in the future with many determinants. "Problematic" is something people define for themselves, and may range from aesthetic concerns at one extreme to a hole rubbed through at the other. Some people try to minimize wear and so maximize the life of their parts (in this case, racks). Others view racks as consumables to be replaced periodically, as geocycle stated. Either approach is a legitimate tradeoff and choice for the users who prefer them. We each come to some personal determination of what constitutes a legitimate lifespan for a product. "Long" to one person may be "short" to another. The many variables result in a substantial range in serviceable lifespan for a given product in a given application.

And right above this is another photo and caption discussing how a stainless steel bolt breaks and is replaced by plastic cable ties, with plastic again proving to be more durable than steel

A full discussion of materials science and bolt yield strength and tensile strength are beyond the scope of this thread, but in general, stainless fasteners are not as strong as higher grades of hardened steel (Grades 5 or 8, for example), and should not be used where a high-strength fastener is appropriate. There are many grades and compositions of stainless steel. The average stainless steel bolt is only a bit stronger than an unhardened ("soft") Grade 2 steel bolt, which is considered rather low-strength. A stainless fastener may have adequate tensile strength, but will have significantly less yield strength than hardened steel. Most stainless steels cannot be hardened like regular steel because they have a lower carbon content. Some stainless steels are particularly prone to strain/work hardening and as a result are more prone to breakage ("yield"). The thing that makes stainless steel so rust resistant is a high chromium content, on the order of 10%-11% and up, depending on the alloy's composition. In contrast, common 4130 cro-moly steel has about 1% chromium content by weight. Bottom line: Stainless bolts are pretty and rust resistant and suitable for most bicycle applications where those concerns apply. However, If one is most concerned with avoiding breakage, it is best to avoid stainless steel bolts and instead go with a hardened steel bolt. With regard to my own stainless steel bolts, I select higher grades and use through-bolts that extend beyond the bosses, securing the free ends with nylock nuts serving as jam nuts. This prevents vibratory loosening and gives me a second means to remove the bolt should it break (flush-fit bolt shafts are devilishly hard to extract in field conditions; see example in link referenced above). I also pack spare bolts in my tool kit.

Most of the above discussion relating to the qualities of stainless-steel bolts also applies to stainless-steel racks to a degree, and accounts for Tubus' own lower load rating for their stainless racks.

I'm not too worried about plastic wearing through the cromoly steel used on Thorn's racks.

With all respect, to each his own. The rate of wear and concern over it will vary by application and individual preference. Several months ago, I had the opportunity to view a world tourist's bike firsthand. He has been on the road for two years and is running cro-moly Surly racks front and rear. He used Ortlieb compression straps on his large Ortlieb rear bags and rack wear was minimal. His Ortlieb front bags used only the Ortlieb mounting hardware and hook-and-stabilizer fin-caused rack wear on that rack was enough to catch a fingernail -- about 0.5mm. I have no idea the wall thickness of the tubing Surly used, but the wear to the front rack was obvious and more than on the rear. Was it severe? I don't know. We talked about it. He isn't worried, while I would do something about it. Either view is as valid as the other and is down to preference and personal risk valence. Again, to each his own.

Hook-caused rack wear leading to a cycle of rust and further wear can be easily addressed by getting some clear vinyl aquarium tubing (which is fairly soft and comes in a variety of diameters and wall thicknesses), slitting it lengthwise, and fitting it over the rack rails. The Ortlieb mounting hooks are then fitted -- sans spacer shims -- to the larger-diameter sleeved rails. This reduces rack wear and prevents accidental loss of the spacer shims, which has been a problem for some. Other people have used innertubes or a variety of other materials, as noted earlier. Related links here:
http://www.woollypigs.com/2011/09/fettling-ortlieb-pannier-hooks/
http://www.woollypigs.com/2010/06/ortlieb-bike-packer-plus-rear/
http://www.crazyguyonabike.com/reviews/board/message/?thread_id=38352&page=1&nested=0#127860
http://www.shanecycles.com/about/my-gear/handy-stuff--tips?tmpl=component&print=1

Since the OP's question (seeking a replacement rack to avoid rust problems) has been answered to his satisfaction, I will leave it there for this thread except to note that nylon formulations -- especially the glass-filled/reinforced varieties often used in many structural applications of bicycle components and accessories -- can be remarkably tough and amazingly abrasive when applied in fretting loads (back-and-forth lateral or rotational movement), particularly as the nylon composite ages and weathers and the glass fibers are directly exposed, increasing rack wear. Bicycle-related science is fascinating and often surprising.

For those interested, a few related links with regard to stainless-steel and other materials in relevant bicycle applications:
http://reviews.ebay.com/Stainless-Bolts-Usually-very-weak_W0QQugidZ10000000001623345
http://www.boltdepot.com/fastener-information/Materials-and-Grades/Materials.aspx
http://www.brightspoke.com/c/understanding/bike-frame-materials.html
http://bicycles.stackexchange.com/questions/1920/are-rusting-screws-a-sign-of-cheap-bad-material
http://www.bssa.org.uk/
http://www.bssa.org.uk/topics.php?article=122

Best,

Dan.

[Andre Jute]

Bottom line: Stainless bolts are pretty and rust resistant and suitable for most bicycle applications where those concerns apply. However, If one is most concerned with avoiding breakage, it is best to avoid stainless steel bolts and instead go with a hardened steel bolt.

The presumption here is that you will work within the sizes of bolts normally used to fit racks to a bike, M4 or at best M5 bolts. But there is no reason that you shouldn't drill out or tap out a steel bike to take M6 bolts, and if you're ordering a semi-custom bike like a Thorn anyway, and you know it is for strenuous service, then you can always ask them to do it for you, and provide the highest tensile rating of stainless they can obtain in the bigger bolts. (One of my bikes, which has a reputation as a world tourer and comes with a ten year guarantee, is built as a default with taps for bolts one size up on standard all round.)

I admit to being partial to stainless steel even though I can get a good quality of blacked high tensile steel socket screw at trivial cost from my local hardware store.

Tip: If you can't get high tensile stainless screws locally -- and the likelihood is that you can't unless you live in a city and have access to engineering suppliers -- a good place to order them is electronic mail order merchants, in the UK RS and Farnell, in the States places like Mouser. Problem is, you might have to buy a box and that can get to be pricey if you want only a handful.

Andre Jute