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Freehub interchange/compatibility

Old 05-02-22, 10:23 PM
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Freehub interchange/compatibility

Hi folks,
At the co-op where I volunteer, we have been getting in a lot of quality wheels with Deore LX or XT 7 speed freehubs. We also get in many trashed wheels with good 8+ speed freehubs these hubs are usually marked, made in Thailand or China, but the freehub is unmarked. Is there info available as to which of these are compatible wich the older, better quality hubs? When servicing these for use on refurbed bikes, it would be easier to replace the freehub than to do a major rebuild on the wheel and provide us with a more usable wheel.
Thanks & regards,
Van
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Old 05-02-22, 11:42 PM
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Not sure exactly what you are asking.

A freehub consists of the hub and a freehub body. The complete freehub is laced to the wheel. If you are talking about taking a Shimano 7 speed freehub body and install it on a non-Shimano hub, it probably wonít work as the attachment will be different.

When it comes to unbranded it is hit or miss with what will swap from other unbranded or non-Shimano freehubs.

I donít know of any cross reference of compatibility. I would also guess that there may not be a consistent freehub body attach interface over the years even within the same mfg; except Shimano has been pretty good with mix-n-match between newer and previous generations.

Finally, if the refurbished bike has 8 speed shifters, you should use an 8 speed cassette, which wonít fit on a 7 speed freehub body.

John
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Old 05-03-22, 01:42 PM
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Hello again,
Sorry for the confusion. All the hubs are Shimano. What we want to do is replace the 7 speed freehub on an older, good quality wheel with an 8 speed freehub from a trashed wheel. These wheels usually have an Acera or similar level Hub. The reason for this is that the 8 speed components are more readily.
Thanks again,
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Old 05-03-22, 03:13 PM
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You’ll probably need to move the 8 speed freehub body DS cones, maybe the dust seal (if they are different diameters). Depending on the bike dropout width and OLD of the hub, you might have to swap out the axle.

There is also a high probability that the wheel will have to be re-dished with the wider freehub body.

The one other caveat that you will find when you remove the freehub bodies is the flange/hub recess are not all the same. If you can match thin flange to shallow hub recess and thick flange to deep hub recess things will line up better.

A thick flange in a shallow hub will cause the freehub body to extend further out. That may not be a major issue. But putting a thin flange on a deep recess hub may not give enough spoke head to cassette cog clearance as the freehub body sits deeper.

John

Edit Added: Dura Ace 74XX has a different attachment. Also there are a couple of external splines that won’t work, but easy to spot.

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Old 05-03-22, 08:13 PM
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Why do you need to do this? 7sp freehubs can take 8 & 9 sp cassettes since the cogs get narrower to fit on the freehub body. Stick with the ones you already have especially if they are LX or XT. I've put 10sp on a 7sp LX wheel and it worked fine, except it would only fit 9 of 10 cogs. I rode it that way for a few months and then decided to just put in a 10sp LX hub as I wanted it to match the dynamo front wheel. I recall swapping the hub by swapping the spokes one at a time. All leading spokes on one side, then all trailing on the other etc... I did this 9 years ago and I was riding that wheel yesterday on the 5BBT here in NY, as good as new. And with a 10sp 11-34 cassette on it. I can't remember which cog I had to remove as I thought they weren't all loose cogs.
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Old 05-04-22, 01:50 PM
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8 sp cassettes will not fit on a7sp shimano freehub body. Usually, the 8sp body can replace a 7, but you will most likely need to replace the axle and redish the wheel.
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Old 05-04-22, 05:33 PM
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Originally Posted by davidad View Post
8 sp cassettes will not fit on a7sp shimano freehub body. Usually, the 8sp body can replace a 7, but you will most likely need to replace the axle and redish the wheel.
Who is using 8 speed cassettes? They were just an oddball size. You can't get them, you can't get compatible parts. Why even try to use them unless you already have it on a bike? What is the advantage beyond an extra cog?

Is the spline pattern different? Is it the thickness?
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Old 05-04-22, 10:18 PM
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Thanks for the feedback.
Please understand that this inquiry is for work done at a community service, non-profit bike co-op. We provide training & bicycle transportation for the disadvantaged by rebuilding discarded & donated bicycles with recycled parts. Our expenses are covered by retail sales of parts as well as rebuilt bikes. Our customer base wants safe, reliable bikes and are not interested in the latest technology. Thus, we try to use what is readily available to us. All bikes are fully serviced & get new cables. Many get new housings & tires/tubes.
As a competent, amateur bike mechanic, I’m aware of most of the requirements for these changes. I also appreciate the additional info provided.
Best regards,
Van
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Old 05-05-22, 08:12 AM
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Originally Posted by Senior Ryder 00 View Post
Thanks for the feedback.
Please understand that this inquiry is for work done at a community service, non-profit bike co-op. We provide training & bicycle transportation for the disadvantaged by rebuilding discarded & donated bicycles with recycled parts. Our expenses are covered by retail sales of parts as well as rebuilt bikes. Our customer base wants safe, reliable bikes and are not interested in the latest technology. Thus, we try to use what is readily available to us. All bikes are fully serviced & get new cables. Many get new housings & tires/tubes.
As a competent, amateur bike mechanic, Iím aware of most of the requirements for these changes. I also appreciate the additional info provided.
Best regards,
Van
I get that, but I'm still curious as to what is wrong with the full 7sp setup that you'd want to swap things around. I have 7sp DX on one bike and it works great. I've thought about changing it to be compatible with my other very similar bike but I asked myself why do I need to do that if it works.
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Old 05-05-22, 09:05 AM
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Originally Posted by zacster View Post
I get that, but I'm still curious as to what is wrong with the full 7sp setup that you'd want to swap things around. I have 7sp DX on one bike and it works great. I've thought about changing it to be compatible with my other very similar bike but I asked myself why do I need to do that if it works.
I think the OP is saying he doesn’t get fully functional bikes and isn’t making the change for the sake of it. He is trying to take a good wheel with a 7 speed freehub body and replace the body with an 8 (8-10) speed body to use on a bike with 8 speed shifters, or 9 if that is the case.

John
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Old 05-05-22, 12:40 PM
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Originally Posted by zacster View Post
Who is using 8 speed cassettes? They were just an oddball size. You can't get them, you can't get compatible parts. Why even try to use them unless you already have it on a bike? What is the advantage beyond an extra cog?

Is the spline pattern different? Is it the thickness?
8sp cassettes - Google Search
Do you know that 9 and 10 speed cassettes also fit?
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Old 05-05-22, 01:11 PM
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Originally Posted by zacster View Post
Who is using 8 speed cassettes? They were just an oddball size. You can't get them, you can't get compatible parts. Why even try to use them unless you already have it on a bike? What is the advantage beyond an extra cog?

Is the spline pattern different? Is it the thickness?
I use 8 speed cassettes. Well truth be told, I use 7, 8, and 9 speed cassettes and space them to 8 speed depending on what I'm looking for. Even when I ran my DX UG/HG, I spaced the cassettes at 8 speed, and ran 7. I found 8 speed trigger shifters used to be dirt cheap and better than the 1st generation bowl triggers.

Cassette cog thickness varies from 1.85mm (7) to 1.80mm (8) to 1.78mm (9). This is a maximum .07mm or .003". Of course this is traditional cog thicknesses. Inexpensive modern cassettes seem to all be are around 1.80mm and the difference is made up by the plastic spacers, which are all over the place as far as thickness tolerances.

The nicest thing about 8/9 speed cassettes is you don't have to run an 11t, (if you only want 7 or 8), and found in nearly all modern cassettes. Dump it an run a 1st position 12t or 13t. I have one setup with a 14t first position. Used to be able to find them when juniors were running 14-28.

Personally I think 9 speed was the best design between no-brainer maintenance and decent gap control. Of course the 1x wide range setups have displaced the 9 speed gap control advantage.

John

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Old 05-05-22, 02:22 PM
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Originally Posted by Senior Ryder 00 View Post
Thanks for the feedback.
Best regards, Van
Van: If I thought I needed to apologize for the reams of off-topic 'advice' you've received in this thread, I would.

Back to the issue of freehub compatibility: I also volunteer at a Co-op and have done many freehub transplants. Most Shimano 8/9/10 freehubs can be transplanted onto most Shimano 7-speed cassette hub shells. With the usual caveats such as axle width, dust cap compatibility, spacers under the freehub, appropriate cones etc. If you are in a Co-op setting, you'll have drawers of replacement parts, and I'm sure you can make it work.

Of course old Dura-Ace cassette stuff is not compatible with anything but itself, and the old Uniglide press-fit cassette bodies are orphaned as well.

I've been stymied only a few times by replacement freehub bodies, and these are from the lower-end RM line of Shimano freehubs. These have a completely different shape than 95% of the other Shimano freehubs out there. If you are scavenging freehubs off of any mid-range and above Shimano hubs, they should work.
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Old 05-05-22, 04:39 PM
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Well, it is possible to just re-space the cassettes to match the shifter pull, if the cogs are not spidered, and run 7 of 8, or 8 of 9 if you don’t want to play mix-n-match with freehub bodies. Just block out unused shifter positions.

Only caveat is to use care that you don’t jam the shift against the RD low limit screw. Allow for a very slight play/gap/shifter movement.

I imagine there will be a mix of when a swap makes sense and when it doesn’t warrant the time to do a swap.

John
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Old 05-05-22, 06:14 PM
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I've gone the other way. Installing 7-speed freehubs on various Shimano hubs. There is a lot of incompatibility. There are a couple of oddballs, but many work. Then I'll set the axle to fit, and build and dish the wheels as needed.

I think they were all genuine Shimano hubs. I've found that the freewheel races were generally of good quality no matter the hubs, but the cheaper hubs had cheaper cones.

Anyway, if you have some junk wheels, keep the freehubs (or entire hubs) and try them out the next time you need one.
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