I brought my road bike on a flight last week and after I put it back together I immediately noticed it felt slow and muddy. It felt like I had brake rub or a mushy back tire. I'd say it feels about 1mph slower but it's hard to say. It's been imperceptible to others who've ridden my bike but it definitely feels wrong to me.

  • I checked the tire pressure, it's fine

  • Brakes are not rubbing, and tires are not rubbing on chain/seat stay either.

  • Both wheels spin freely and more or less trued. I have mavic rims and hubs. Bike rolls fine downhill but when climbing it feels extra heavy and I hear the slightest rubbing sound.

  • Drivetrain is clean and lubed

  • Opened up the bottom bracket and it's a bit worn but fine

  • I'm not sick or under the weather.

What could have so suddenly happened? I do know that TSA opened my bike box as one of their random inspections, so maybe they did something to it? I thought maybe the wheel axles had bent, but they seem straight to the naked eye. Could it be something else along the drivetrain? I'm just very confused.

Edit: I rode in the rain yesterday and realized that everytime I stood up, there was a scraping sound near the back wheel on every left pedal stroke. What could be causing this? Sounds like the wheel might be flexing and hitting the brake

  • Check jockey wheels. If fine, buy new bike.
    – Noise
    Commented Sep 8, 2022 at 18:32
  • Was your flight returning from a cycling holiday where you did significantly more riding than usual?
    – Andy P
    Commented Sep 8, 2022 at 20:57
  • 1
    Are you positive you where actually riding slower? I've had that feeling. I do not always use timing or tracking devices, but recently I had such a "brake rub" ride while tracking with a gps device. When I compared the ride with a previous one (same bike, same route), I was actually marginally faster. My guess is I was somehow "tired" and rode harder to compensate.
    – Jahaziel
    Commented Sep 8, 2022 at 22:56
  • @AndyP yes, why? It was actually 3 months of heavy riding :|
    – 900edges
    Commented Sep 9, 2022 at 10:33
  • @Noise would "not fine" be worn out? they seem a bit worn but otherwise spin without resistance
    – 900edges
    Commented Sep 9, 2022 at 10:34

3 Answers 3


Check the routing of the chain around the derailleur.

I've had a case where the chain was riding on the metal nubbin but it wasn't loud or noticeable, because that's on the low tension side of the chain so it was just dragging.

Even if you didn't unship the chain, its possible to get it running weird around jockey wheels which will add some small resistance.

Get the bike off the ground, try free-spinning the wheels. You're looking for faster-than-expected slowdowns. Could be wheel bearings are under/over tension, adding drag.

Last resort is you may just be having a bad couple days, some lingering flu/cold that isn't enough to notice but enough to impair you. Drink plenty of water, get a lot of sleep, and eat some extra fruit/veges.

  • 1
    Thanks, but the wheels were spinning freely. It was only when riding (in particular, climbing standing - see edit) that it would feel slow.
    – 900edges
    Commented Sep 12, 2022 at 14:14

Interesting. While you say you were not sick or under the weather, maybe some long effects of having asymptomatic Covid. I had a couple days early on in June on the bike and on runs with co-workers where things just weren't right. I got dropped on a section of a work ride where I just don't get dropped, my co-worker just rode away like Boonen did with Terpstra PR 2012. I was gassed, there wasn't even anyway I could have attempted to standup for a little oomph to get back on his wheel. And on one run, I just had to walk.

At that point we were well into running and riding upwards of 4x a week. I say it was worse then the early spring rides when we're just getting back into it after a few months of cold weather. Like day to day, work activities, unaffected, but exertion-wise there was no turbo boost.

I wasn't sick never felt sick. I had traveled via plane, recently to a sister office the week before--so aside from three days of inactivity, best I can figure is I prob'ly contracted Covid, was asymptomatic as far as any "cold-flu like symptoms" or any other tell-tale adverse normal illness affects, but definitely had lung issues.

Just my two cents, because it sounds like you covered the basis, I would have done wheel alignment in the dropouts--if QR, brake rub, either rim or disc. Hubs, and heck you checked out he BB. I would say it's either physical body, or mental ala Carlos Sastra flipping his brake releases off at the top of climb before a decent.


Noise from left pedal..hmm..and "worn" bottom bracket?

What type of bottom bracket you have?

If it's something with outboard bearings like Hollowtech II, GXP etc, it may be a bearing failure.

More probably, your bottom bracket is not perfectly concentric. Is it a carbon frame?

Bent axles will cause wobbly wheels in almost all cases, so a small possibility. Still, I would check the bearings. All Mavic's I know have perfectly nice cartridge bearings. Faulty cartridge bearings does produce a thin, treble sound rather then scraping under speed, or scraping if they are shot very, very badly but for bearing failures at that degree, you'll hear it constantly.

I think it's bottom bracket, still. It's hard to judge where the sound exactly comes from, especially riding the bike.

  • I've got dura-ace 7800 (I think that's hollowtech 2?) on a carbon frame. How do you check if the bottom bracket isn't concentric? It is true that I haven't maintained it for many many miles. I think I've come to the conclusion that the axles/hubs are fine :)
    – 900edges
    Commented Dec 12, 2022 at 21:14
  • You'll have to check bottom bracket shell actually, not the bottom bracket itself. It's too hard to do, as a tool like caliper is not precise enough, and useable. It's a good idea to go to a machinist's shop. It may not be concentric, and also two sides may not be aligned correctly due to poor welding or loose tolerances. You'll be looking for a deviation less than a milimeter. Commented Dec 13, 2022 at 1:21

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