i would like to know is that possible changing from 9spd free-hub to 11spd free-hub?
my new bike come with 105/11spd. but my old bike wheel set is ultegra 9spd hub. can i just change the free-hub to 11spd so i can use that old wheel set for training and will not waste money?

Nope.

You need to remove some length from the left side to make it 130mm again and re-dish the wheel after you fit the cassette body. The wheel won't be as strong.

Or you could get fancy and have an 11s cassette machined down to overhang the hub flange; the spacer to fit 8/9/10 onto 11s is 1.85mm, so 1.5mm should do it. I have a 10s billet cassette with some metal taken off the back, fitted on a 7s cassette body mounted on a WH-RS80 @132mm for great victory.

Google 11s cassette on 10s hub.

Nope. The Shimano 11 speed freehubs are not compatible with earlier versions.

What! That's a ******y move.

There's a mob called Lasco Concept you can buy machined 11s cassettes from. https://darkspeedworks.com/blog-11speed.htm

Yes it was. In addition to modifying as you mentioned, Shimano now has a 34t 11 speed cassette that will fit the 10 speed and lower hubs. There was a thread recently.

The Ultegra R8000 11/34 cassette will fit a 10 speed body. Cassettes with smaller large sprockets will not.
Edco makes an 11 speed monoblock cassette to fit a 10 speed body. As mentioned, there are various hacks such as machining the back of the mounting spider, but that can make spoke clearance dangerously slim.

My 10 on 7 has about 4mm, but then some of that is due to the better spoke angle from taking dish out of the wheel (which was the whole point of the mod).

buy a new wheel with the fancy 11 speed hub.

Unless you are stripping all the 11 speed stuff of one bike to build the other.. Dont bother...



9 was when road and mtb stuff had cross over potential.. better touring bike use.


Plenty of 9 speed stuff sold, so though its not the latest trend, bike shops still can get repair , service parts..







....

I would be interestd too know will an 11 speed cassette fit on a 7 speed hub by dropping a cog or two simlilar to 8 of 9 on 7.
Currently using 7 of 10 on 7 130mm which is fine.

Why would you mount 7 of a 10 cassette on a 10 speed 130mm hub?


I imagine you could put some fraction of 11 cogs on a 7 speed freehub, as long as the cogs came apart individually.

It'a 7speed hub spaced and dished 130mm for a stronger wheel
Well i was thinking about 1 by systems (but just thinking) and i realised i like two chainrings and maybe i could entirely eliminate chainrub in all gears ( which i couldn't quite do). I know i don't need a 12 or 13 so i moved the cassette otbd for better chainline. 28/14 7 speed 52/38 double. Also thought about 1/2 step but it won'really work either.
For where i ride 7 well chosen gears is perfectly fine but if there was another option with 11 i might look at it.
But as it stands i am happy with what i have it's just curiosity.

And so as not to derail the o.p.s original question if he had an 11 speed group he wanted to use. He could just use 10 of 11 or 9 of 11 and choose the ratios he didn't want or need and keep the wheel as is.
Maybe the simplest option depending on why he wants to do it.

While I agree with this, it kinda defeats the point as his bike came with an 11s group but he wants to use a 9s wheel. He'd have to remove one cog to fit a 11s cassette onto the freehub, but then he'd have to adjust his limit screws to keep from shifting off the cassette. Having to re-adjust the derailleur every time you switch the wheel would be a bit of a PITA.

Depending on what wheel it is, I'd say a better option would be to get an 11s hub and rebuild the wheel. That's what I did with my Open Pro's. Had an Ultegra 6600 hub, rebuilt it with a 105 5800. Spoke hole diameter was the same, so I was able to re-use the spokes I had. That being said... If it's something like the Ultegra 6700 tubeless wheel, probably going to have to just replace the wheel.

11s wheels without an off centre rim or 2:1 spokes don't have enough NDS tension, IMO

Even if it will not, which might be very likely depending on the exact hub you have, it's not costly to replace them on most hubs.

If you have the skill needed to unscrew and replace the cassette, then certainly you can replace the free hub body. There might be other things you'll encounter, but they too shouldn't be costly or insurmountable. You might find the wheel needs to be dished differently. Maybe not. You might need different axle spacers. Maybe not. Will it be perfect? Does perfection matter for the purpose you are using it for?

It all depends on exactly what you have and are getting. So finding out exactly what the hub and freehub body are that are on the wheel currently, going to the manufacturer's website and digging for specs will help you determine what you can expect.

Keep us updated on what you encounter.

If it will work it needs to be the 105 because it still uses the 10mm axle. It looks to be the same diameter as the 9sp.
You will need to remove a spacer to get the same width over the lock nuts and probably need to redish the wheel.

Hmmm.... I just noticed you did say "ultegra 9spd hub". So if it is actually an Ultegra 9 speed FH-6500 hub, maybe you can't just switch the free hub body. There are some differences looking at the parts diagrams.

But there is also the possibility of changing the entire hub and using your old rim. Might not be too much at some shops. Don't know.

The people who have already responded to the thread noted that Shimano does not make an 11 freehub body that will work on their previous hubs.

"Changing the hub" is rebuilding a wheel from scratch with new spokes and is a rather expensive proposition. Better to just buy a cheap 11 speed wheel.

Yeah, they were specific about shimano. I should have taken that as a clue and looked to see that the OP specified that. But I didn't til it was to late.

Might be true of all freehubs except Mavic as far as putting an 11 speed cassette on one that previously had 9 speed.

But this one way I learn. Posting my misconceptions and getting it ripped apart.

Yes, for years before the 11 speed era Mavic hubs required a spacer. When 11 speed came out they were already good to go.