Trying out rare combinations of cassettes and hubs can be very interesting. Sometimes it brings great benefits and sometimes it just brings risks.
So, that brings us to the question can you use 8 speed cassette on 7 speed hub?
Yes, this combination is feasible. It can increase your cost-effectiveness and gear range. It can make your gear shifting smoother. On the contrary, it can damage your lockrings and engage the freewheel too much. You might encounter breakage and unexpected stops. Also, all gears might not engage.
There are pros and cons to using this combination. But you need a bit of better understanding before gearing up and riding your bike while having this combination.
So, let’s get started!
Is it Possible to Put an 8-Speed Cassette on a 7-Speed Hub?
Some people have expressed concern that a 7-Speed Hub doesn’t support an 8-Speed cassette. Here you’ll find the conditions if you can really do it.
To begin, it’s critical to understand how many teeth each gear size has. On average, each gear size will have at least 34 teeth. So, in this case, an 8-speed would be 40.
Most cassette manufacturers use a two-part cassette body with two lock rings. The inner lock ring or the one that is threaded is splined. And it determines which hub the cassette will be compatible with.
If the spline on the inner lockring can’t be seen, the cassette is for a 9-speed hub.
We can’t tell you if your 7-Speed hub is suitable without knowing what shifter you have. However, there is a simple method to find out.
In this scenario, all we have to do is count the number of gears. Count the gears between your largest and smallest sprockets. 8-Speed Hubs will have 16.
Find out the gears on your 7-Speed hub. If there are 14 gears between your largest and smallest sprockets, then that’s bad news. It means your shifter is not compatible with an 8-Speed cassette.
Your options will be to either put a smaller chainring on your current hub. Alternatively, acquire a 9-or 10-speed cassette with the same number of sprockets.
You might wonder, can you put a 10 speed cassette on an 8 speed hub?
Yes, that will work perfectly. Freehubs with 8,9, and 10 speeds are identical. If you’re talking about a road bike, a 1mm spacer behind the Shimano cassette is required. If you’re talking about a mountain bike, it’ll go straight on.
If there are 15 gears between your largest and smallest sprockets then it’s good news. It means you can use an 8-Speed cassette. But it may not fit without modifications. However, there are some merits to this setup and some demerits.
Depending on the number of teeth, the shift ramps on an 8-Speed cassette could be too tall. It’s for the gap between your largest sprocket and the lock ring.
How to Fit an 8-Speed Cassette on a 7-Speed Hub?
The 7-speed cassette must first be removed from the hub. Remove any brakes from your bike as well. After that, remove the 7-speed sprocket by unscrewing it with a wrench and sliding it off.
Take note of which sprocket holes are open and which are not. This will allow you to reconnect with them afterward.
Install the 8-speed cassette with all of the sprockets into the hub. Do this so that all 8 openings on each side match up. Replace any spacers on either side with one from your kit that matches in size. Fill up any spaces you may have left between pieces, usually every other space.
This is a very simple process. You can do it in case of fitting a 9-speed cassette with 8-speed hub.
The 8-speed hub will have the same number of sprockets per side as your 7-speed cassette. So you can use a new cassette with it. There will be less “play” between the sprockets. And you’ll have to spread the chain out more in each gear.
The chain doesn’t normally need to move that far, but if it shifts then it shifts. If you don’t like where your gear is, try taking out one chain ring. Or take in another chain ring. So that each gear has a similar amount of space between gears.
All of these can be done if you have only one tool and some basic handy skills. The tool I’m referring to is an adjustable wrench. I normally use the IRWIN VISE-GRIP Adjustable Crescent Wrench.
However, you can use the Olympia Tools Adjustable Wrench, which I’ve heard a lot of.
Benefits of Using 8-Speed Cassette on 7-Speed Hub
Sometimes there are bikes with a 7-speed hub and an 8-speed cassette. When deciding on the ideal gear ratio for your bike, this might be complicated. The Benefits of using an 8-speed cassette on a 7-speed hub are the following-
The cost of an 8-speed cassette is less than a new entire new 3 or 7-speed derailleur. This makes it a more cost-effective option from the get-go.
Increased Gear Range
A bigger gear range means your gearing will stay constant for long periods of time. Because you can change gears in more places. This, therefore, saves you energy and time when riding uphill. Or doing frequent climbing exercises at high speeds.
Gear Shifts are Smoother
All of the 8, 9, and 10-speed cassettes have the same sized cog spacing. So the change from a small to a big cog in an 8-speed cassette is smoother. Smoother than that of a 7-speed cassette. This makes it easier for you to shift up or down when needed.
A smoother gear change means you save energy and time when going uphill or climbing. Also, the power of newer bikes is increasing. As a result, you may want to double-check that your gearing is as suitable as possible.
So these are some of the benefits you can get from using this combo.
Demerits of Using 8-Speed Cassette on 7-Speed Hub
Using an 8-speed cassette on a 7-speed hub is a rare combination. Also, this is often discouraged by the veterans due to the occasional lack of compatibility without modification.
So you should be ready for the risks as well. Here are some of the issues that might arise.
Lockring Might be Damaged
Sometimes, using cassettes of different widths might damage the lockring. So you might be unable to tighten the cassette lockring.
To fix this sand the inner and outer sides of the cassette lockring using high-grit sandpaper. The rough surface will provide enough traction to allow it to slide into your 8-speed cassette hub.
Freewheel Engaged Too Much
The freewheel might engage too much because of this combination. This will cause too much friction under a heavy load. And this can have a high chance of destroying the cassette and/or hub’s bearing(s).
To solve this you can just replace the freewheel or replace the forks. Here’s an easy tutorial about replacing your bike’s freewheel
All Gears Not Engaging
This rear combination can sometimes cause a distraction for the gears. And so all the gears might not be engaging.
To solve this, you can replace the 8-speed cassette with a 7-speed freehub body. This solution alone will solve your problem.
The main demerit of using this combination is that the gears will be too far apart. Which makes shifting more difficult since there isn’t enough space in between each gear.
Although the likelihood of breakage is rare, it can still happen. Then you’ll have to replace your entire rear derailleur and shift cables as well.
Lastly, if you’re considering this combination then you should also consider investing in some upgraded brakes. You should also learn some bike hacks before installation.
Are all cassettes compatible with all hubs?
The majority of cassette hubs are compatible with Shimano cassette cogs. Shimano’s inter-sprocket spacing is shared by SRAM cassettes. As well as most Miche, IRD, and SunRace cassettes. Certain SRAM 10-speed cassettes, on the other hand, are incompatible with Dura-Ace hubs with aluminum bodies.
Is it possible to upgrade my freehub?
Yes, you can replace the hub, but you’ll almost certainly need new spokes. A good technician will charge $50 or more for the job. It’s not worth it unless you have a really outstanding rim.
Is it feasible to combine different hubs?
You can’t mix and match various brands of freehub/drivers. Each hub manufacturer and model has its own freehub/driver to hub interface. If you need to replace your freehub/driver, make sure you obtain the same model and brand.
We hope now you know what you needed to know about 8-speed cassette on 7-speed hub.
Do you want to find out what more your bike is capable of? Are you willing to take chances? It’s all up to you.
We can only wish you the best of luck. So get out there and break a leg!