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| The BIKETUBES TPU fat bike tube. |
The TPU innertube has caused quite a stir since it came aroiund several years ago. Limited sizes, stories of fragility, and the price kept a lot of folks away. However; more sizes, stronger designs, and lower prices have conspired to create something of a buzz around TPU tubes.
I recently discovered that TPU tubes are now available in fat bike tire sizes with both 26" and 27.5" diameters being covered. There are no really wide sizes yet, but many riders could benefit from the 4.0 - 4.5" width that is being offered at this time.
I ordered three of these tubes. Two to go in my 2011 Salsa Cycles Mukluk and one as a spare for my Ti Mukluk. This use as a spare or bail-out tube is one of the benefits of TPU tubes. TPU tubes have less mass and take up a lot less space in your kit. I'll get to a comparison between butyl rubber fat bike tubes and these in a bit, but I will give you a spoiler - There is a massive difference!
These tubes are available on BIKETUBES website and cost me about 68 bucks for three with free shipping.
What It Is: TPU stands for "Thermoplastic Polyurethane". The material is made into tube shaped "hoses", cut to length, bonded at the ends, and fitted with a valve stem. TPU can be colored, it can be clear, and it is 100% recyclable. TPU tubes can be patched in case of a puncture, (and these tubes come with two patches each) but as of now, no sealant is recommended to be used in a TPU tube. The good news is that TPU tubes are better at resisting punctures than butyl rubber tubes.
TPU tubes also feature the benefit of very low rolling resistance when used inside a bicycle tire. Research done by a competing TPU tube brand has shown that TPU tubes are almost as low, in terms of rolling resistance, as tubeless, and slightly better than a latex tube would be. This is a very big deal when it comes to fat bikes due to the increased surface area that the TPU tube contacts when inside a tire.
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| It doesn't take much convincing when it comes to pack size as to which tube I want. |
Rolling resistance differences aside, what will really strike you at first is just how crazy light these fat bike TPU tubes are in comparison to a normal fat bike tube. Each TPU tube I purchased weighed in at around 143 -148 grams each with the TPU band and plastic Presta Valve cap. The total weight of butyl rubber tubes I removed was 965gms/2.13lbs. The total weight of the TPU tubes installed in the wheels of my Mukluk is 287 grams/.63lbs. The missing one and a half pounds makes a HUGE difference in rolling weight, not to mention the lowered rolling resistance.
Installation: TPU tubes are not that much different than butyl tubes when it comes to installation with the exception that TPU can be a little fussy when it comes to giving the tube some shape to get it installed. It is also recommended by many TPU tube brands to lightly talc the insides of the tire. I already had this done so I was good to go.
TPU is a little less friendly to abuses than butyl rubber during the installation process, so take care to not pinch the tube between the tire and rim, and by no means should you ever use a tool to install the tire. (That goes for butyl rubber tubes also) Proper installation technique will make this very possible. Being a bit gentle with TPU goes a long way toward success.
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| My 2011 Mukluk. You cannot see the TPU tubes but they are in there. |
My Mukluk still runs the old Larry 3.8 and Big Fat Larry, which is more like a 4.5"- 4.6" tire. The TPU tubes are rated for this range of sizes, and I had no issues getting the tires mounted. I used a SILCA Terra pump which is designed to measure more accurately at low pressures. I went with 8psi front and rear for the initial set up.
The only negative I see is that the valve stem, which in this case is also made of plastic and could be easy to bend. Care needs to be taken when applying a pump head so as not to damage this stem material, whatever it is.
The Ride: I took the Mukluk out on some local gravel, dirt, grassy fields, and alleys. The lack of weight was immediately noted, obviously, but what I did not see coming was how these more flexible tubes allow the fat tires to work better. Tubes made of butyl rubber give these tires a stiffer ride by far. I thought I had some fancy, high-TPI fat bike tires on the bike, not these old, stiff Larrys!
I'm sure the lower rolling resistance is awesome and the weight is better, but I'm telling you that it is the tires and the way they feel 100% different, in a good way, than before is what I am most excited about. The ride was dead smooth and even riding over a small, two to three inch diameter branch was like riding over nothing but smooth pavement. I wouldn't even have known I rode over that but for seeing it coming and hearing it snap when I rode over it. (Note: I've pulled the Redshift ShockStop post since the image was taken and still feel the same about the tires.)
Too bad we don't have any snow to try this out on. I'm very curious to see if this newfound flexibility and smoothness would increase flotation and traction. But maybe later, eh? We've missed out on all the big storms so far this Winter.
I'll be riding these in the coming weeks and be back with an update. So far, I am very impressed despite the possible fragile valve stems and the steep price.
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