An auto article from the 1920's noted:
The pneumatic tire, the very thing that makes the automobile practical, is one of its most fragile parts. — Unknown
In the 100 or so years since, auto tires have improved dramatically. Yes, they still go flat, but not often, and some new cars even come without a spare tire.
Meanwhile, bicycle tires have also improved, but not so much. Bicycle tires use thin rubber and run at higher pressures, so over a few days can lose enough pressure to increase rolling drag. Also, bicycle tires are commonly punctured by glass, wires from truck radial tires that have thrown their tread, and in some areas from thorns of common plants.
Several times, I have gotten a slow leak that I did not notice, then later in the ride I hit a small pothole or the like and got a pinch flat. After fixing the pinch flat, I continued to ride, only to get another pinch flat, as I had not fixed the initial slow likea. This inspired me to want a pump in the hub that would (a) make noise to let me know when the tire was losing pressure; and (b) help keep the tire inflated until I reached someplace it was convenient to fix the flat.
Fast forward several years, I had a roughly 10 km commute (20 km daily) and in 28 days of February got 28 flats. Rain regularly washed debris from the roadside out in to the road, and a frequent light drizzle kept the sharps and tire rubber well-lubricated. Many leaks were slow enough I could keep riding if I stopped often enough to pump up the tires. That would let me finish the trip and patch the tube in comfort of the garage, but stopping every half kilometre to pump up the tires is also time-consuming, so if the flat was early in the commute, I would stop and change the tube right there. One ride, as I stood in the rain under a street light changing the tire, I again wanted a tire pump driven by the wheel.
Given experiences like the above, I was interested in about 2008 to see the announcement of "Pump Hub" www.pump-hub.com, and more intereste in 2012, to see them for sale.
Here are some "use cases" where a hub-mounted pump could help me:
Slow leak, as above — keep riding, with the pump on, until it is convenient to stop and repair the leak.
I have had frame pumps stolen a couple times. Small pumps can fit in my bag, but small pumps are often awkward to use or ineffective. Also, I sometimes forget to move a pump over when I switch bags. A hub-mounted pump is always with the bike, and unlike a frame pump, a hub pump is easily locked, at least if you lock your wheels anyway.
Tires lose significant pressure over a few days, and I often neglect to top them up. Low pressure increases rolling drag, so slows me down — as well as increasing the risk of pinch flats. Thus, improving the convenience of top-ups helps me go faster. A hub pump is not the only way to do this, but convenience is a big factor in how oftne I use it.
Nothing is perfect, but some things are more imperfect than others. There will probably always be somebody for whom it is the right solution, but I care if it works for me and more generally if it works for lots of riders.
Here are some possible problems:
Reliability: A great idea is no good if it breaks. Pump Hub could be a lousy hub or a lousy pump. It could suffer any of various novel problems, for instance the pump could stop working. Or, it could suffer ordinary problems, for exmaple the flanges could break or the ratchet could break.
Convenience: If Pump Hub is a good pump but is hard to use, I won't use it — I will use an ordinary pump instead.
Cost: Somebody remarked "There's price and then there's cost. 'Price' is what comes out of your wallet when you get it, 'cost' is what comes out of your wallet to own it." Even if the hub is reliable, if it costs a lot to buy, or costs a lot to keep working, something else is better for me.
Weight: As with cost, if Pump Hub works well but is too heavy (more below), I won't use it.
Here is what I know so far: it uses standard cartridge bearings, a hardened axle (standard for quality hubs), a Shimano freehub mechanism, and flanges with significant material outboard of the spoke holes. The parts are made in USA by reputable shops, for example the hub shell is made by Paragon Machine Works. The guy who runs Pump Hub has been using them enthusiastically since 2008, as have some other folks — albeit in the San Francisco Bay Area, which is not hostile towards equipment. I bought a pair of hubs for US$200, and the front weighs about 300 g and the rear about 475 g.
I cannot yet comment on durability. For top-up convenience, I tried them on a demo bike and they seem great, although a fully-automatic on/off system would be even better. For flat-tire convenience, they seem a little better than a mini-pump although not as good as a good frame pump. It is time-consuming to spin the front wheel long enough to inflate the tire to where you could ride. Mini pumps I have used are also time-consuming, prone to damage the valve stem, and hard to the get full pressure. Pump Hub is time-consuming but assures you of no broken stem and full tire pressure. A frame pump achieves high pressure reliably and conveniently, though as noted above it is no good for dealing with slow leaks and is hard to lock on the bike.
Thus, from what I know so far, Pump Hub could be a great solution for me. It is slightly heavier than the hubs + pump I use now, but I expect the weight will be more than offset by reduced rolling drag, due to keeping my tires at full pressure. Similarly, I have repatedly had slow leaks where a pump like Pump Hub could have let me keep going. I do not yet know if Pump Hub can pump fast enough for typical slow leaks, but if it can, the improvement in convenience will again more than outweight the cost and weight.
Whether Pump Hub works for you depends on your use. Even ignoring reliability concerns, you won't ever see a Pump Hub on, say, a track bike. Track riders don't carry pumps anyway, or even the wrench needed to remove the wheel should they flat. On the other hand, there are many riders for whom a little price and a little weight is a good tradeoff, at least if the hub works reliably.
Another buying consideration is what else you have at the hub. Pump Hub is not yet available with a disk brake flange, but it should be later. Pump Hub cannot be retrofit to another hub, so will not work with a hub generator, drum brake, coaster brake, internally-geared hub, disk or "tri-spoke" wheel, and so on.
Different riders have different priorities: some riders will spend over US$1,000 on a hub; others will spend less than US$100 on a whole bicycle. Comparing convenience and reliability is hard, so as a starting point we compare price and weight.
Following are price and weight comparison of Pump Hub with some other commercial products. Prices obviously vary, and weights even vary from year to year, but the following should be broadly true.
All hub weights are with skewers; Pump Hub does not include skewers, so American Classic at 94g/pr and MSRP US$20 are used.
|Shimano 105 2012||US$117||630g||Topeak Road Morph G||US$39||260g||US$156||890g|
|Shimano Dura-Ace 2012||US$590||455g||Topeak Micro Rocket Carbon||US$45||55g||US$635||510g|
|Pump Hub 2012||US$220||870g||—||—||—||US$220||870g|
Shimano 105 hubs are durable and used widely. The Topeak Road Morph G is designed for easy use and has a pressure gauge to avoid tire under- or over-inflation. Together, the 105 hubs and Road Morph G pump are about 75% the price of Pump Hub and similar weight — about 20 g heavier than Pump Hub.
Shimano Dura-Ace hubs are "racing class" equipment and are also used by cyclists seeking lower weight than with Shimano 105 hubs. Though they are about 2/3 the weight, they are also about 5 times the price. The Topeak Micro Rocket is difficult to use, with long tire inflation times and a reputation of damaging valve stems, but at 55 g is also quite light. Together, they are about 3 times the price of pump hub and about 60% the weight.
The above suggests that for most cyclists, those using hubs with similar price and weight to Shimnano 105, Pump Hub is a good alternative if it has enough reliability. It costs only slightly more, saves a little bit of weight, and offers "daily use" convenience and through proper tire inflation should help riders go faster and avoid pinch flats.
However, the above also suggests the most weight-conscious cyclists will not want to use Pump Hub — such riders are willing to pay a high price to save grams, and will probably also trade reduced convenience to get lower weight. There's nothing wrong with that, it just demonstrates Pump Hub could be a win for many cyclists, but not all.
Pump Hub is more expensive than a conventional hub and pump, so the main reason to use it is greater convenience. This section will eventually have an "initial impressions" review.
In simple "bench" testing of a demo bicycle, Pump Hub is very convenient for topping up the tires. It takes no tools and just a few seconds to turn on both hubs. I have not tried it with gloves, but it appears that will also be convenient.
For a fully-deflated rear tire, Pump Hub is convenient if you are willing to turn the bicycle over and rest it on the saddle while spinning the cranks. Lifting the rear wheel and holding it off the ground is somewhat less convenient, as it takes significant time — not just a few turns of the cranks &mdash to get enough pressure to ride. The front is even less convenient.
In my very limited experience so far, Pump Hub is significantly but not dramatically less convenient for flat tires than a Topeak Road Morph. Them main disadvantage of Pump Hub is that it takes a while spinning the front tire to get enough pressure to ride; it seems like significantly more time than with the Road Morph, although I have not measured it. In contrast, the rear wheel is easy to spin with the cranks.
In my limited experience, Pump Hub is significantly more convenient on flat tires than the Topeak Micro Rocket. The Micro Rocket is difficult to use, even more difficult to use to achieve full pressure, and is prone to damage the valve stem. I have not timed it, but believe Pump Hub is as fast or faster to get you back on the road, even for the front tire, and with much less risk of tube damage.
Even if Pump Hub turns out to be convenient, nobody will want to use it if it is likely to break. This section will eventually contain a long-term use report.
Pump Hub has been in use by the designer since at least 2008, and by some other riders for several years following that. There have been many changes since the initial demonstration model, suggesting the most significant reliability problems have been solved in the current model.
Pump Hub uses a Shimano cassette mechanism, so in principle that part of the mechanism should be as reliable as widely-used Shimano parts.
Most of the wheel bearings are widely-available industrial cartridge bearings.
Many hub parts are specific to Pump Hub. As long as Pump Hub is in business, parts should be no issue. It is more likely that Pump Hub will go out of business than, say, Shimano, so there is some risk parts will be unavailable in the future. For riders on the tightest budgets, risk alone may be an issue. For many riders, the expected cost from the risk should be small: you both need to have a failure and have Pump Hub go out of business, one or the other is not a problem.