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A friend of mine is riding consistently in largest chainring front and smallest cog rear. The corresponding teeth counts are respectively 44 and 11.

The bicycle is an Acera-level mountain bike with very light and fitting them frame. Gears shift relatively quickly and reliably.

Their average speed is about 30km/h, while commuting 20km total per day. The traffic is average.

Their acceleration at traffic light is low. However, I have observed no other drawbacks. To my surprise, the chain and smallest cog are still operational, after 1-2 years of year-round commuting - dust, snow, salt, mud, rain. (measured with a chain ruler)

Also, when it becomes impossible to ride this gear (standing up), they switch to a much much easier gear.

Is this a reason for concern? Knees, traffic safety, mountain trekking endurance, bike components wear (from most important to least important)?

EDIT: A couple of clarifications:

  • The tires are 26x2.0 semi-slicks.
  • It was a mistake to claim average speed of 30km/h. This is rather cruising speed. On the other hand, starting from a red light or recovering from a difficult turn takes forever (5 seconds for example).
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What is the rider's cadence? He should be maintaining at least 60 rpm. If not he's apt to blow out his knees. –  Daniel R Hicks Apr 7 at 19:45
    
(Though it should be noted that 44/11 is not a terribly high gear ratio -- it's the top end of my tourer, and that's not an aggressive bike. Not that I spend much time in that gear, except downhill.) –  Daniel R Hicks Apr 7 at 19:48
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But I work out his RPM to about 28 -- far too slow. He's gonna blow out his knees and cause other injuries. –  Daniel R Hicks Apr 7 at 19:55
    
@DanielRHicks How did you work that out? Using the Sheldon Brown Gear Calculator, I got around 30 km/h for the speed at 60 RPM. I Tried with a variety of tire sizes, and they all ended up close to 30 km/h, which is stated as the rider's average speed. –  Kibbee Apr 7 at 20:12
    
@Kibbee - I worked through the math, but definitely it wasn't a robust computation. 30 km/h = 8.33 m/s. A 700c is around 4.4 m in circumference, so a little less than 2 rps. Divide by 4 for the gear ratio and you get about 0.5 rps or 30 rpm. (Oops, I figured the circumference wrong -- it's only half that, so closer to 4 rps and 60 rpm.) –  Daniel R Hicks Apr 7 at 20:38
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2 Answers 2

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As commented by @Daniel R Hicks the problems I would be concerned about are to his own health. The bike components that will wear out prematurely are simpler to replace.

Potential health issues are knee problems from "mushing" all the time. MTBer's tend to run lower cadence than road riders, for valid reasons, but when on the road tend to run closer to road cadence. Mushing causes excessive pressure on the knee, causing the joint to wear out - its an Orthopedic surgeons retirement plan, in 20 years time he will be doing knee replacements.

The other concern is mixing it with traffic in high gear. You have limited ability to accelerate and your balance is often compromised. Under usual conditions, not a problem, but in an emergency that could be the difference between a close call and a grease mark on the road.

Less of a concern, and people physical attributes vary, is endurance and aerobic capacity. The reason for spinning faster is it provides maximum aerobic efficiency. Under about 80RPM you are not able to maximize the power output of you legs. Beginners often spin too slow, as the optimal cadence needs technique and practice to learn how. To some it feels you are going faster mushing as it feels like it takes less effort if you spin faster. I find a good test is to get them to change down a gear, keep the same effort and monitor their speed. Most are surprised to see an instant increase of 1 or 2km/h for no more effort.

If you are really keen to get him to spin faster, put him on a bike with short - really short (like 145mm off a kids bike)- cranks for a few rides. As you have much lower torque, you have to spin to go fast, but spinning smoothly is easier, so you just do it. It's a great training aid.

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So it is bad. Now I have to find where to ask one of those question so popular in the Workplace.SE: "My boss/colleague/friend/relative is wrong and I am right; how to convince them, for everyone's good?". –  Vorac Apr 8 at 6:47
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Is it bad? How old is he - in his 20's - he won't feel it - so no, its not bad, 30's - he will get over it- no, 40's, its hurting him - yes but good luck getting him to admit you are right, 50's - he saw a knee surgeon last week but no way in hell hes telling you that, 60's yes, but can't teach an old dog new tricks :) –  mattnz Apr 8 at 10:28
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I'm guessing the guy does it because he thinks it macho, and likely telling him he's hurting himself will only make him more stubborn. But then I'm sure a lot of fixie riders are doing the same, so it's a big club. –  Daniel R Hicks Apr 8 at 11:53
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Good point about accelerating in traffic. This goes for both too low and too high of a gear. If you are spinning at 120 RPM, you won't be able to accelerate to get out of a bad situation either. –  Kibbee Apr 8 at 12:42
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Riding everywhere in one gear is usually not a good idea, unless you're on a SS/fixie. And SS aren't a good idea everywhere (like where I live, for example, an island with almost no flat spaces at all), but the gearings they have are usually somewhere in the mid-range, where you can speed up relatively quickly, won't blow yourself out cruising, but won't be winning any races, either.

Heaviest gearings may contribute to knee problems, but the much more immediate concern is that it makes riding a bike more of a chore than it should be. I live in a hilly place and I'm nearly constantly changing gears, and when I go someplace flatter I still find myself changing gears all the time based on wind. The only time I don't is sidewalk riding, 4th-grade style.

So... if your friend wants to ride 4th grade style, that's his issue (and his knees, if the medical thing is true). For people who spend a good bit of time on their bikes (commuting in my case) riding in the biggest gear everywhere sounds like a bad idea.

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