marq1

At first I thought it was the tires, then noticed my normal 3 1/2 hour ride was taking 4 hours, then today I gave it a test.

So this goes back to a new Specialized Crosstrail that I picked up recently when my Trek 7200 (both Hybrids) had a bottom bracket issue and didn't look like it was going to make it, another story.

I had both bikes hanging from the ceiling, spun the tires and the Specialized stopped spinning at 37, the Trek 128. Tried the rear, Specialized 28 Trek 78, WTF!

Very non scientific, just counting but what a difference, the Specialized has always felt slow.

Novice mechanic, but have checked the disk brakes, air gaps so they are not the issue, what do you think, something with the hubs bearings? Over tightened?

cny-bikeman

There is simply no way that your results prove anything - a wheel that spins around multiple times will not slow you down by any significant amount, certainly not by the amount you note (14%). The hubs on the Specialized may have seals (or tighter seals) but it's not enough to make a difference you will detect. Unless the wheel is almost locked up (they would stop spinning very suddenly) the hubs are not the problem. As for "over-tightened" just Google adjust hub - sheldonbrown and parktool sites are the best.

The way to approach this is the same as with any diagnosis.. When did the problem start? Was there any change you made to your bike, the time you ride, or have you noticed any other physical changes in your body preceding that time?

JohnDThompson 

Unloaded drag is entirely irrelevant to loaded performance. Your problem is elsewhere. I'd start by looking at the tires.

habilis

Unscientific though your method may be, it reveals a difference in your hubs that I would find disturbing because it may reflect a problem with bearings. You may want to remove the "slow" wheels from their frames and check for smooth turning of the spindles with your fingertips. If you have cup-and-cone bearings, make sure they aren't adjusted too tight. If backing them off a bit doesn't free them up, the bearings need to be overhauled.

The issue is premature bearing failure, not energy lost while pedaling. Whether it's revs or seconds of spinning that you're counting, that big a difference is abnormal.

70sSanO

According to what I found, I think your Specialized Crosstrail has loose ball (cup-cone) hub bearings.

Follow the suggestion above... take off the wheels and turn by hand. They should be smooth, or at least pretty smooth.

I'm betting a bad cone adjustment.

...but if they are smooth, it's not the hubs.

John

JohnDThompson 

The difference in unloaded drag is most likely from the bearing seals. The "slower" hubs are on a new bike, where the seals have not yet worn in. I suspect in a year the difference will be less or even entirely absent. And in any case, it has no bearing on loaded performance when the bike is actually being ridden.

catgita

After the quick checks mentioned, swap the wheels, see if the problem follows. Then swap the tires.
Riding position check too.

FBinNY 

Sorry, but this is simply wrong. The two prior posts have it right -- the unloaded spinning and drag are virtually meaningless. the forces involved are tiny compared to what's involved with a loaded bike (compare the inertia of a wheel weighting a few pounds to that of a bike and rider weighing 50-100 times that (or more).

Unloaded bearing drag variance usually reflects such things as more or stiffer grease, and /or seal drag. If you want to see a major change in unloaded drag flush out the grease and tun the bearings on oil, and remove any contact seals. Or try a simple experiment now that winter is coming. Spin the wheel while it's indoors and warm, then put outside to cool and repeat the test, and see how a small change in the viscosity of the grease can make a (seemingly) big difference.

habilis

Please note that I wasn't attributing the OP's longer riding time to the wheel bearings. For that to be the case, the bearings would have to be nearly locked up. I was ONLY addressing his experience while spinning the wheels manually.

The OP should check if he has cup-and-cone bearings. If so, the wheels that turn almost three times more easily are properly adjusted and greased. The others are IMO not behaving normally. I've used a few different kinds of grease - mostly, automotive wheel bearing grease. For a particular grease to slow the hub down that much, it would have to be close to tar in consistency. Maybe it would still lubricate effectively, but I'd be uncomfortable using it.

Sealed bearings are another matter. My only experience with them has been with ones that are well broken in. New ones may indeed slow the hub down by a factor of three, I don't know. Still sounds odd, but the OP's hubs are new and deserve a chance to break in if they are sealed.

My MTB has cup-and-cone with a thin rubber dust shield. It may cause some drag, but it's infinitesimal and can't compete with the mass of the spinning wheel.

No doubt, cold temperatures affect the viscosity of fluids, including grease, but it's just not that cold yet where I live.*

Taking away grease consistency and dust shields, what's left? With cup-and-cone: Over-tight adjustment, dirt in the bearings, or damage to the bearing surfaces. Whichever the case is, they need attention.

*Interesting historical note: In Russia, German planes were sometimes grounded during the winter of 1942 due to temperatures dropping to -40 F. The hydraulics froze.

marq1

Some comments in the posts, this is simply an AB comparison to my older hybrid to the new bike. One died on Monday (but was revived) and the next bike was ridden on Saturday so no change to the rider. Agree with comment about tires (second behind wind) as being greatest factor, but as noted that was addressed the second week with new tires so both bikes have the exact same tires. And lets not forget the input of the rider, from day one this bike has just felt slow.

However, I disagree with the statement that unloaded drag is irrelevant. I checked out the Sheldon Brown article on bearing adjustment, he states:

When you are holding the wheel and turning the axle by hand, the only load is the weight of the axle set and the viscosity of the lubricant. When you are riding your bike, the load is the weight of you and your machine, and the frictional drag is increased by many times.

If a hub is too tight, the bearing surfaces will self destruct prematurely, and the bike will not roll as freely as it should.

If there is so much drag on the free spinning wheel then it's going to be intensified with the load of the rider. Since all other variables have been ruled out, rider, tires, and brake drag not sure there is much left!

So, since the discussion has not revealed other possibilities, then next step is to do a quick check on the hubs/bearings before the next ride to see if some gross adjustment was made during assembly! I'll report back the findings.

habilis

I like your thinking. Sheldon also explains that too-loose adjustment allows the balls to move away from the radiused part of the cone and ride on the cylindrical shoulder, where they concentrate wear on a thin line. Bad for both the balls and cones.

If your bearings are cup-and-cone and are new, they are probably adjusted a little too tight.

yooperbiker

Except for maybe under inflated tires or failed bearings, I would say by far the most likely problem is the engine. If difference is between bikes, most likely issue your bike fit. The wheel spin test doesn't mean anything. If you felt binding or crunching when spinning wheel, that might tell you something is wrong, but counting revs for a spin down - nada.

cny-bikeman

The unloaded drag is not completely irrelevant - it just contributes so little to slowing you down that it is insignificant
The discussion pointed out (twice) the variable of your position (fit) on the bike. Given the circumstances that is the most likely culprit - not bearings.Thank you for finally disclosing that the times were on two different bikes, and that the 2nd bike was slower from the beginning.

JohnDThompson 

+1 this. The contribution from unloaded drag is small enough that it is completely overwhelmed by even a minor change in wind velocity or direction, or tire pressure, or specific path over the pavement or any of a myriad other factors between test rides.

marq1

That 11" of show we got last weekend interrupted the bike repairs but yesterday I was able to take a look.

The front hub would barley turn by hand. I disassembled, inspected, repacked with a lighter grease.

The unloaded front spin increased from 37 to 73.

The rear hub was not as tight, performed same repairs.

40 mile test ride and the bike was improved, it actually coasted rather than quickly slowed down.

So ultimately the unloaded spin test was a relevant indicator of a problem.

What I don't understand is that I assume the hubs were set at the factory vs LBS. Not something I would have ever expected to find on a new bike.

cny-bikeman

The unloaded test is unnecessary. All you had to do was feel the hub initially. We did say that the hub would have to almost not turn to have an effect. Even at that it would not increase your time by more than a few minutes. Lighter grease makes no appreciable difference.

One can fully expect to find hubs too tight from the factory on a new bike. That's why it's important for the LBS to adjust them out of the box.

fietsbob

Another thread was having a rim run out issue .. radial contact sealed bearings are easy rolling but are a bit loose side to side..

Angular contact bearings can be tightened up, (& mis adjusted ) loose ball cup and cone, most common on bikes,
are a type of angular contact.


[ bigger the wheel rim the slower the hub has to spin for a given rate of speed ]

Al1943

Hubs with dry worn bearings turn much faster than properly greased and adjusted hubs - until they fail.

Vintage Raleigh

My boss at bayside cycles used to take a bearing out of each side and run a drop or two of oil when track racing. Those wheels used to spin forever and you could hear the tic tic of the bearing drop as the wheel slowed down.