wodcommuter

Hello,

I commute on a 1994 Trek 820. It's been a reliable bike all these years until today.

After much searching on the internet, it would seem that my freehub body is shot. When I pedal forward, nothing happens. The gears turn, but the wheel never engages. Pedaling forward has the same effect as pedaling backwards.

I would like some clarification on what is required to replace the freehub body. Search results indicate that its not difficult to change it, all is required is a 10 mm allen wrench. It also requires removing the cassette which, fortunately, I know how to do. Where I get confused is that some sites indicate that the whole hub needs to be overhauled. This may be more work than I am ready to take on. Anything dealing with replacing bearings and removing all the spokes is quite scary to me.

So my question for the mechanics are:

1. Is the problem really with the freehub body and not something more serious?

2. Can I get away with just replacing the freehub body and not have to deal with bearings and the wheel dish stuff which is way over my head? I have found the 7-speed STX-RC and 10mm allen wrench online for a total under $25 - this is can make it past the family council budget committee review (if you know what I mean)

3. If a hub overhaul is required, and I purchase the required bearings, grease and cone wrenches, how tough of a job is it really for someone who has never done it before?

Another option would be to replace the wheel all together. There are some wheel sets online for around $100. However it is unclear if these wheel sets include a freehub body, and if they do, it is not clear if they would fit a 7-speed Shimano cassette. Also, the original wheels are perfectly good (and true). I don't know that I would get the same quality for $100.

Any advice, comments or suggestions are greatly appreciated.

Thanks.

mcoomer

It sounds like the engagement pawls inside your hub are shot. Engagement pawls are spring loaded bits of metal that lay flat when you pedal and make a clicking sound but when you pedal normally the springs force the pawls to engage teeth inside the hub to drive the wheel. These pawls will wear out over time and I suspect that's what has happened to your wheel.

Before you buy anything, take the hub apart and see what's wrong with it. If it's the pawls your LBS may be able to order a set for you, but if the tire is an odd brand, design, or is very old that may not be possible. In that case, or in the event of a more serious failure, I'd say just buy a new wheel and not worry about rebuilding or replacing the hub. Complicating this is the fact that you don't seem to have much experience working on bikes. Here is a guide from Park Tool that will walk you through removing, inspecting, repairing, and reassembling a freewheel body.

Having said all that I would simply look at a budget wheelset. You can probably get by for less than $100 and given that you're using them for commuting they won't have to be bombproof, just a solid wheelset. Shop around on the net and local shops and see what kind of deals you can find. The hassle of finding parts and tools and doing the rebuild may outweigh the cost of a new wheelset.

Mike

DeafLamb

I wouldn't bother going through the bother of Park tools instructions on freehub overhall. They are cheap enough just to replace. The problem is to take them off to replace, you need to remove the axial. This is why you end up doing a hub overhall. The best way to do it is just to remove the locknut and cone on one side of the axial. This way you can just repack the hub with grease and replace the removed locknut and cone and not worry about redishing the wheel or anything.

A cone wrench is 8.99 at the shop I work at, and is porbably the only extra tool you would have to buy, besides the 15mm allen. Tools are always a good investment, or you could just have your LBS do it.

-ray

Bill Kapaun

The DS hub bearing race IS on the FH body.
Thus to change the FB body, you're already dealing with those bearings
To change the FH body, you also have to remove the ale, thus you are dealing with the NDS bearings too.
IOW, it would be foolish to NOT inspect/repack or replace the hub bearings, since you've already done 90% of the work.

The pawls may be just gummed up??? You could try removing the cassette and trying to spray a solvent such as WD-40 in and about the FH mechanism. It's worth a try, IMO.

IF you are capable of swapping a cassette, toy're capable of changing the hub body. Finding the 10MM Allen wrench will be the biggest problem.

operator

1) Take the cassette off and lube the inner edge of the freehub to see if you can get it to unstick. usually this is all it takes
2) If 1 doesn't work the FH body is like $20 and is simple to replace.

HillRider

It's a Shimano, not an off-brand, but you still can't get just the pawls. Freehub bodies are so inexpensive and so elaborate internally (umpteen tiny bearings and shims) that nobody but the most dedicated actually overhauls them. If solvent washing and re-lubing the internals without disassembly doesn't restore proper operation, replace the whole thing.

As noted, the drive-side bearings are actually in the freehub body and the axle has to be removed to remove the freehub body so a complete hub overhaul is certainly warranted.

Since you already know how and have the tools to remove the cassette and have the 10 mm allen, all you need is a tube of grease and a cone wrench. You can probably reuse the hub's bearing balls too but replacements (18 x 1/4" balls) cost pennies each. Park Tools has instructions on hub overhaul to guide you.

Retro Grouch 

"Replacing freehub - is it worth it?"

Yup. Once you do it you'll wonder why you had worried. It's a confidence builder job.

BCRider

And after you work your way through the freehub body cleaning or swap then do your front wheel bearings. If you've had the bike that long without cleaning and relubing it's well past time to do this job.

The only really fussy part is setting the preload on the cones. But even then it's just a bit of do and re-do until you get it right. When you set the preload tighten the cone until there's no play and then tighten another 1/8 turn or so. You're looking to feel a small increase in axle stiffness but not to where you can feel the bearings biting and "cogging". You can get a feel for this before you tighten the lock nut. Remember that tightening the locknut adds more preload so you need to back off the cone about a 1/4 turn. Snug up the locknut and test. Work the pair back and forth a bit until it's set and only then tighten it. If your axle uses quick release skewers you'll wan't to have them in place properly tight during this setting.

wodcommuter

Wow, thanks for the feedback!

Your replies are encouraging. At least, no one mentioned removing spokes. I don't remember what web site mentioned this. Perhaps it was for a road bike or something.

I'll be borrowing my sister-in-law's bike for next week. This will give me time to order parts and tools online. Now I've got a project for next weekend. Before then, I will remove the freehub body and spray it down with some WD-40 to see if it helps.

Thanks again for all your replies. It all seems less scary now.

Cheers!

BCRider

Keep in mind that hosing the freehub down with WD will maybe make it work but it'll certianly also wash out most of the grease from the DS wheel bearing. So use the WD treatment only as a way to evaluate the need to buy a new freehub. If it does and runs smooth then fine, you only need to flush and oil it. But you'll still need to pull the axle apart so you can clean and re-grease the wheel bearings.

Also to get to where you have a spot to squirt the WD into the freehub you'll need to remove the cassette and the little dust shield that is just under the cassette lockring. Once you're in that far you'll see the wheel bearings staring at you. The slot between the outer freehub shell and the non rotating bearing cup is where you want to squirt in the WD.

None of it should be scary. It's all just about doing one easy little job at a time. It's only scarey if you look at the list all at once.....

Bill Kapaun

IF you have a QR axle, you have to adapt to that when setting the bearing cones. The QR will actually compress the axle slightly, removing "slop" from the bearings.
You'll probably have to make 2-4 attempts to get it right, so be calm. It's normal. Initially, just set them a TINY bit looser than you would expect.

FLYcrash

wodcommuter, no hub overhaul ever involves the spokes. If you mess with the spokes, what you're doing is called wheel truing, spoke replacement, or just a plain wheel rebuild. In fact, in some cases (especially whenever there are threads tightened by pedaling torque) the wheel must be intact to work with the hub.

You just mess with the hub while the rest of the spokes, rim, and all that jazz just hang out, fully assembled and still at tension, minding their own business. Go for it! Even a full hub overhaul (including freehub body replacement) isn't all that hard and will teach you a lot about bikes.

Then, when you're comfortable with that, start messing with those spokes and learn wheelbuilding. It's difficult but ultimately really fun and really good for your ego.

rickowensis

Best practice when rebuilding a hub is to carefully inspect the races, cones and ballbearings for any sign of wear, discoloration or roughness. If you see wear on the races, cones or bearings, it's time to re-evaluate the project.

No appreciable wear- ALWAYS REPLACE BEARINGS- they become ovalized through usage, will never settle into the same spot they were in before the rebuild, and are very cheap to replace. Buy a few extra as they have a tendency to get lost.

Appreciable wear- All components are usually affected; bearings, cones and races. If only the bearings and cones are affected, these can be replaced but be very careful to match them EXACTLY as they come in quite a variety.
It MAY BE worthwhile to buy a new wheel at this point as the cost of 2 cones and the bearings plus the time to complete the project may offset any small savings you may realize. Also, the races will have some wear so you would be putting new parts on races which are very slightly worn which will cause the new parts to wear at an accelerated rate.
If the races are affected, it's time to buy a new wheel as the hub is TOAST.

mike

cassettes are fun to take apart. If you can take it apart, clean it, and put it all back together so it works, then you may have a career oppotunity in fixing old watches.

Like a lot of the other posts said, with cassettes costing only $12 for the low end models (Nashbar.com is having a sale right now), you might as well replace it or have a replacement handy.

Every wrench should have the experience of taking a cassette, freehub, and freewheel apart.

Bill Kapaun

Cassettes are simple! Free Wheels are a pita.

I didn't see where a lot of the other posts mentioned replacing the cassette, since this thread was about the FH body?

wodcommuter

Hello all,

Here's an update on my adventures into replacing the FH body. It turns out my chain whip had a 15 mm cone wrench, so all I needed was a 10 mm hex wrench which I got from the hardware store. I took everything apart and discovered what the problem was: the FH body had cracked length-wise into three pieces. Also, one of the pawls was floating around, but I don't know if this happened during the disassembly. So my follow-up question for the mechanics is why did this happen? I can only guess that I must have over-tightened the cassette the last time I replaced it 12 months ago. Could there be any other reason? I'm not an aggressive rider, and none of the hills to and from work are too tough. I rarely get out of my seat.

Also, I need some help with the vocabulary. I've identified the bearings (balls), the pawls (beaver teeth inside the FH body). I am assuming that the races are where the bearings sit, and the cones are what screw into the bearings to keep them in the races. Is this a correct assumption?

There is no sign of roughness, pitting or discoloration with the bearings. The surfaces the bearings are in contact with seem fine too. I cleaned everything thoroughly with some WD-40. Nonetheless, I will replace the bearings as recommened, and use the proper bike grease for re-assembly.

By the way, what is the difference between grade 25 and grade 300 bearings besides price. Will the less expensive grade 300's get me to work and back for, say, the next 5,000 miles?

Thanks!

Bill Kapaun

Sometimes parts just break-
Your vocabulary appears to be correct-
Get the grade 25. Your labor is worth using better parts, and the price isn't that much more. It's simply false economy to scrimp!

HillRider

This myth won't die it's well deserved death. Bearing balls do not "ovalize" with use. Bicycling magazine's tech editor used to perpetrate this false idea for years until an engineer from one of the big bearing manufactures finally wrote and put it to rest.

I've reused bearing balls in Shimano, Sun Tour, Maillard, and Campy hubs many times over the years and never had any problems getting the hubs adjusted to run smoothly, with no play, and they held their adjustment for thousands of miles afterward.

That said and as you noted, even good bearing balls are cheap, and can be replaced at low cost so you might as well do it.

BCRider

If the outer sleeve cracked into three pieces then you can just toss the whole thing away and there's no need for new bearing balls other than for the wheel axle. When you buy the new FH you'll get all the stuff inside at the same time. This includes the wheel bearing cup race for that side.

LIkely you cracked it if you overtightened the nut to great excess. Because they have those locking teeth to work with you don't need excessive force. I believe it says 40-Nm on the center nut? That's around 29 foot-pounds. A smart but not grunting pull on a typical wrench.

HillRider

Do the bearing balls, cone and any seals also come with a new freehub body? I've never bought a new one, only transplanted bodies from one hub to another to upgrade a 7-speed hub to 8/9-speed or to replace a bad freehub body with one salvaged from another wheel so I don't know what is included when you buy new.

LarDasse74

No. All you get is a working freehub body with a single installed bearing race.

Bearings are available for pennies each, cones and axles are available separately, and sometimes as an axle set. Unless there is pitting or an obvious groove worn into the cones they don't need replacing, plus it can sometimes be a PITA to find the correct cones for a particular wheel.

FWIW, A whole new wheel w/freehub body, about the same quality as what came on a Trek 820, will probably cost between $40 - $60.

HillRider

That's what I thought. BCRider's posting led me to believe all of the other parts for that side of the hub came with the freehub body so I wasn't sure.

FLYcrash

I agree with Bill's statement that the grade 25 bearings are worth it. If you want to save money, hit up an industrial supply house (I use McMaster-Carr at mcmaster.com). You can get 100 1/4" bearings and 100 3/16" bearings, grade 25, 52100 chrome steel, for like $7 plus S&H. That's enough to get several bikes running smoothly even if you throw in a Sturmey-Archer gearhub or something.

I think it's telling that McMaster-Carr doesn't seem to carry ball bearings any worse than grade 25 even though they have a magnificent selection of balls in general. I also really love that you know the spec of your bearings (material, Rockwell hardness, tolerances, ...) when getting them from an industrial source, but that might be more about nerdy satisfaction than an actual performance increase.

HillRider

The Grade number gives sphericity variability in 1,000,000th of an inch so a lower number is better. Also, better grade balls are made of stronge and more corrosion resistant steel and through hardened rather than just surface hardened. The minor cost difference is worth it. BTW, Grade 25 is the best normally available.

vrkelley

To the OP:

I experienced a similar problem this morning. Blown freewheel on a wheelset with about 6500 miles on them. The shop guy says it's probably some springs that fell off and wanted to charge $100.

Even with regular changes on the Kool Stops, the rims are very worn from the super steep hills around here (always a stop sign at the bottom of each). Since he said the back wheel had about a month of life, and drags out the same Mavic Ksyrium Elite wheelset. No Deal. $$$

Edited: I said in another post that these were ES, I stand corrected these are Elites