How long was the bicycle moving

Albert Einstein? Walter Isaacson? J. Benson Hamilton? Charles Haddon Spurgeon? Dorothy Tucker? William Whiting?

Dear Quote Investigator: The famous physicist Albert Einstein reportedly used a wonderful simile that compared riding a bicycle with living successfully. Here are three versions:

Life is like riding a bicycle. To keep your balance you must keep moving.

People are like bicycles. They can keep their balance only as long as they keep moving.

It is the same with people as it is with riding a bike. Only when moving can one comfortably maintain one’s balance.

Would you please explore this topic? Which version is the most accurate?

Quote Investigator: On February 5, 1930 Albert Einstein wrote a letter to his son Eduard that included a remark that has been translated in different ways. In 2007 Walter Isaacson published a biography titled “Einstein: His Life and Universe”; the notes section at the end of the book printed an excerpt from the original text of the letter in German together with a translation by the Information Officer of the Einstein Archives. Boldface has been added to excerpts:

The exact quote is: “Beim Menschen ist es wie beim Velo. Nur wenn er faehrt, kann er bequem die Balance halten.” A more literal translation is: “It is the same with people as it is with riding a bike. Only when moving can one comfortably maintain one’s balance.” Courtesy of Barbara Wolff, Einstein archives, Hebrew University, Jerusalem.

Further below supplementary citations are presented for alternative versions of the saying ascribed to the acclaimed scientist.

Interestingly, the simile has a long history that reaches back into the 1800s in the English language. The early citations found by QI referred to the religious lives of individuals. Later citations referred to business and secular pursuits.

Here are additional selected citations in chronological order.

In 1882 a periodical about bicycles called “The Wheelman” published a story by Reverend J. Benson Hamilton, and the author attributed an instance of the simile to an unnamed “great preacher”:

“A great preacher,” said he, “says living a religious life is like riding the bicycle: you must go on or come down.”

The words of Hamilton made a strong impression on at least one person. In 1884 a didactic religious text titled “What & Why: Some Common Questions Answered” by Charles E. Pratt included a section called “Words of the Wise”. Pratt reprinted the text above, and he ascribed the words to Reverend J. Benson Hamilton.

In 1890 Reverend Theodore L. Cuyler presented the opening address at the Annual Meeting of the New York State Association of Young Men’s Christian Associations held in Binghamton, New York. During his speech he employed an instance of the simile:

Why, friends, Christianity is very much like riding the bicycle, you have got to keep your headway; the moment you stop, you drop. The whole highway of Christian life is strewn with dismounted wheelmen that have gone over into the ditch.

In 1902 a religious periodical called “The Railway Signal” published an essay by William Luff who ascribed the simile to a prominent Baptist preacher named Charles Haddon Spurgeon who had died a few years earlier in 1892:

Trust as a child trusts a parent’s hand when learning to ride a bicycle, and Father’s hand will hold you up. C. H. Spurgeon once said, “The Christian life is like riding a bicycle: you must go on, or you come off.”

In 1907 “The Life and Sayings of Sam P. Jones: A Minister of the Gospel” included the following remark about the popular pedal-powered conveyance:

Going to heaven is just like riding a bicycle. You have to keep-a-going to keep-a-going. You got to keep a-moving—you can’t stop

In 1908 the “Farm Journal” of Philadelphia, Pennsylvania printed an article of “Feminine Dairy Wisdom” from Dorothy Tucker which included the following:

Dairying is like riding a bicycle,—if you don’t keep moving you will fall off. A herd of dirty, emaciated cows is a plain advertisement of the owner’s lack of brains or his downright shiftlessness.

In 1921 a trade journal in the paper and corrugated fiberboard industry called “The Shears” printed an essay by William Whiting who applied the bicycle simile to secular life overall:

In case of doubt—Go on. No matter what happens—Go on.

Life is like riding a bicycle: we can keep from falling if we keep moving.

Only a few trick-riders can stand still, and not tumble.

In 1922 a writer in the “Bulletin of Photography” applied the figurative language to business in general:

No man can stand still in business. He is going forward or, he is slipping back. A business is like a bicycle. It will fall if it stops. It must go on or it will tumble.

In February 1930 Albert Einstein wrote a letter to his son that employed the simile. The letter was discussed in the 1994 biography “The Private Lives of Albert Einstein” by Roger Highfield and Paul Carter. The authors presented a paraphrase but not a direct translation:

The best cure that Einstein could offer for melancholy was hard work. ‘How beneficial a job would be for you,’ he told Eduard. ‘Even a genius like Schopenhauer was crushed through unemployment.’ He told his son that life was like a bicycle, since a man could keep his balance only if he kept moving.

Walter Isaacson’s biography “Einstein: His Life and Universe” in 2007 included the following translation from German to English as noted previously in this article:

A more literal translation is: “It is the same with people as it is with riding a bike. Only when moving can one comfortably maintain one’s balance.”

Isaacson also presented a less precise translation of Einstein’s remark in the epigraph of his biography. This simplified version referred to “life” instead of “people”. The existence of both versions was somewhat confusing:

Life is like riding a bicycle.
To keep your balance you must keep moving.

In 2005 a biography of Einstein by Jürgen Neffe was published in Germany; the work was translated from German to English by Shelley Frisch and released in 2007 with the title “Einstein: A Biography”. A version of the remark by Einstein about people and bicycles was included:

In February 1933, the famous photograph of the laughing physicist rounding a curve on his bicycle was shot in California. Today it seems like a symbol of his situation at the time after the forced exodus from Germany. “People are like bicycles,” he wrote to his son Eduard in 1930. “They can keep their balance only as long as they keep moving.” 39

Footnote 39. Letter to Eduard Einstein, February 5, 1930; Einstein Archives 75-990.

Interestingly, it is possible to balance a largely stationary bicycle. The technique is called a “track stand” or “standstill”, but it requires careful practice. The technique is mastered by many bike messengers, performers, and professionals.

In conclusion, Albert Einstein did use the bicycle simile in a letter he wrote in 1930. The original remark in German was presented near the beginning of this article. A translation by Barbara Wolff was also presented. The figurative language was also employed during the decades before the 1930s. The subjects used in the simile comparison varied.

(Great thanks to Tina Dickson whose inquiry led QI to formulate this question and perform this exploration. Also, thanks to Nigel Rees who mentioned this quotation in the October 2012 issue of “The Quote Unquote Newsletter”. Further thanks to Ilan Vardi who told QI about standstills.

Update History: On October 10, 2021 QI added the passage about standstills.

One aspect of this question hasn't been addressed by other answers: service intervals.

If you drive a car, you know to lube it every 3000 miles, rotate tires every 7500 miles, flush the fluids every 30000 miles. ... Most components would have reasonably well-defined span they will serve, and would probably start falling apart after this many miles, even with reasonable maintenance and repair. What would the range in time and/or miles be for commuter bikes? road bikes? mountain bikes?

A probable reason for this oversight is that, with respect to the OP, most bike components do not have defined service intervals, at least in terms of mileage. For that matter, I don't know the empirical basis behind automotive service intervals, but I guess I'd have to assume that at least some of them (e.g. replacement belts) are based on some sort of statistical analysis of mean time to failure.

Chains

Chains have the most clearly defined replacement interval, and it's not defined in terms of mileage. It's defined in terms of the amount worn, related to the length a chain has stretched due to wear. A more technical discussion is here at this Cyclingtips article, but 11s and higher chains are replaced when they hit 0.5% wear (i.e. measured length over 0.5% longer than original), and 10s and earlier chains can be replaced at 0.75%. You can replace chains later than this, but you are increasingly likely to wear out the cassette, and if you replace a chain much too late you could also kill the chainrings.

Bikes don't have built-in odometers like cars. Even if they did, the distance before you hit the wear limit will vary considerably due to variations in how often and how thoroughly you clean your chain, the conditions you ride in, the quality of lubricant used, and other factors. Further, most end users likely don't log their chain life. This requires manual effort. Platforms like Strava offer some partly automated ability to do this, but the last time I changed my chain I forgot to note it on Strava, and now I don't have an exact date where I put its replacement into service.

Related to the chain, one rule of thumb I've heard is that if you replace chains at or before the wear limits above, you can get 2-3 chains per cassette, and 2-3 cassettes per chainring. For cassettes, I think they are typically replaced when a new chain skips on the cogs; there are visual guides to detecting worn cogs but I suspect you'll get skipping before visible wear. One discussion of that is at this answer.

Tires, rim brake rims, brake pads

Some tires have wear indicators, which are little dots molded into the tire. Once these become invisible, you would be recommended to replace the tire. Some discussion is here. However, in principle, you could also keep riding the tire until the tread is completely worn away in some spots and you can see the carcass or the puncture belt - that would be a bit extreme, but I suppose you could do it.

For rim brakes, some rims have similar wear indicators. Otherwise, you would check if the brake track is concave - an illustration is here. For disc brake rims, because they don't wear in the same fashion, I don't know that there is a replacement guide, and I think you can keep riding them until the rim starts to crack at the spoke holes. I'm not an engineer, but I assume that eventually the rim material will fatigue enough for that to happen. I don't know what sort of mileage you could expect that to happen at, but it could be very high.

For rim brake pads, there are typically wear lines molded into the pads. Disc brake pads and rotors have manufacturer specified thicknesses that you measure with calipers.

Bearings

To my knowledge, you would typically check bearings for a gritty feeling, as discussed in the terminology index and as mentioned in this answer. If they're cup and cone bearings, you'd want to re-grease them periodically (e.g. annually, consider more if you're riding a lot in wet conditions). Also specific to this type of bearing, the balls and the cones can be replaced when worn. Cartridge bearings are typically designed not to be serviced and to be extracted and replaced when they're worn; again, you'd check this by turning the wheel or crank by hand and feeling how smoothly the bearing turns.

Cables

The performance of shift and brake cables and their housing degrades over time as contamination gets in and the cables stretch. Again, there is no specific recommendation for service intervals. I've heard active cyclists say they replace annually. I know I've been able to stretch my service intervals longer than that with acceptable performance. Others may have different experiences, but this may be one of the most under-appreciated parts about owning a bike.

Higher-end groupsets are switching to electronic versions. These are actuated by a wired or wireless signal, and a motor moves the derailleur. In principle, the average (or median, or whateverth percentile) number of cycles to failure of the motor could be determined in a test setting. The issue would be tracking the number of cycles the motor has cycled through. To my knowledge, SRAM's AXS app tracks the number of shifts and a few other statistics, so in principle it could warn users if the motor hits some sort of lifespan benchmark. It does not do this yet, and I don't believe SRAM have publicly commented on the expected motor lifetime in terms of shift cycles. I am pretty sure that the Shimano Di2 and Campagnolo EPS groupsets and apps don't track this info, although in principle they could.

Frame and fork

Most forks on decent-quality bikes are made of carbon. Higher-end frames are also often made of carbon. Lennard Zinn at Velonews asked fork manufacturers about the potential lifespan of carbon forks. The consensus was that manufacturers weren't concerned that the forks would fail due to fatigue alone - keep in mind that I'm using the term in a lay sense; this answer discussed that fatigue in the engineering/physics sense applies to metals and not to carbon. The manufacturers said that their forks were able to exceed industry-required tests, and that they performed better than metal forks. The same, to my knowledge, is true of carbon frames.

The real issue is that bicycles take all sorts of little knocks over their lifespan, e.g. you lean your bike against the car, and later you open the car door and the bicycle tips over (happened to me), or similar happens at a coffee stop, etc. Not all similar impacts will cause carbon to fail. However, it is possible that minor impacts like these can precipitate an eventual failure, and the damage isn't obvious at first glance. Because of the random nature of such events, I don't believe that there can be a defined service life for frames and forks. You would be better off visually inspecting for cracks at some intervals, e.g. when you take your frame in for annual service. You can also monitor for changes in how the bike feels, e.g. something feels loose or soft. This does depend, however, on your ability to perceive subtle changes.

As mentioned in a comment on another answer, carbon is surprisingly repairable. In fact, it may be more easily repaired than metal bikes - you often need to replace a tube wholesale, but carbon repairs can be localized to just the affected area.