changing a cassette - Shimano Sora

[mmr1975]

I have just started using a road bike.
I have a 11-32 cassette (Shimano CS-HG400) and a 50-34 Chainset Shimano Sora FC-R3000. I
was wondering if it would be possible to change the cassette to a 11-34 to tackle hills more easily or if this would require a lot of changes in my current gearing.
Thank you.

[reohn2]

What rear mech is fitted.

[mattsccm]

If that is the standard rear mech it may be at its limit but generally bikes makers never put anything at its extreme limit so you would probably get away with it. Just might need a longer mech. Look for numbers on the back and let us know.

[robgul]

Agreed that you need to know if it's an SS or GS mech (the latter is probably already fitted if a 32 sprocket) - rule of thumb is that if Mr Shimano gives a "max sprocket" size you can usually get it to work with 2 more teeth (but you may need a slightly longer chain) - OR look at a rear derailleur hanger extender - Wolf is the bee's knees BUT the ebay ones for a fiver work just as well.

Key to checking is with the chain on the largest sprocket and the clearance between it and the top jockey wheel - wind the B screw in to push the mech back.

.... or go to the LBS and ask (I keep a few old cassettes in my shop with big sprockets that can be quickly popped on to a wheel to just see if it will work)

Rob

[Brucey]

if you have a matching rear mech RD-R3000 then there are two versions; SS and GS. The obvious difference between them is the pulley cage length, being a touch over 7cm and 9cm respectively


SS


GS

The GS mech has a larger capacity and is better suited to the cassette you intend to fit.

cheers

[horizon]

I have a 11-32 cassette (Shimano CS-HG400) and a 50-34 Chainset Shimano Sora FC-R3000. I
was wondering if it would be possible to change the cassette to a 11-34 to tackle hills more easily or if this would require a lot of changes in my current gearing.
Thank you.

I had similar gearing (as you know!) on my Tern folder (11 - 30 but 24" wheels) and swapped the chainset (50-34) for a Spa double (42-26). I'm just wondering what the pros and cons are for the two different approaches. (I'm not recommending anything, just trying to increase my understanding.)

[NetworkMan]

Just remember that 32 to 34 is only about 6% lower or about half a gear so don't expect too much.

[horizon]

Just remember that 32 to 34 is only about 6% lower or about half a gear so don't expect too much.

Whereas changing the front chainset might give a much greater difference?

[slowster]

A 34t rear sprocket will give you a lower bottom gear, but not much lower. If the hills where you live are steep/long, and/or there are lots of them, and/or lack of fitness are such that you find the hills difficult to get up with your current gears, then I suspect that the 34t will not make the sort of difference that you are looking for.

This link is a visual representation of your current gearing compared with what you propose, and you can see that the impact of the extra 2 teeth is not a lot.

If you want much lower gears, then it's likely that the best solution is to replace the 50/34 chainset (assuming it's a standard Shimano road chainset, you will not be able to fit a smaller inner chainring than 33 teeth, so going smaller does requires a new chainset). The choice of such chainsets is limited, and the obvious candidate (Spa Super Compact) requires a square taper bottom bracket, so you would probably need to replace the bottom bracket as well. On the positive side this option would allow you to keep your current 11-32 cassette and existing chain (you would just need to shorten the chain). If you fit a new cassette, you should fit a new chain at the same time. Note that this assumes your bike has a threaded bottom bracket shell, rather than being of the press fit type, which would complicate matters.

This link is a visual representation of your current gearing compared with, for example, a 44/28 chainset (or you could have 46/30 or 42/26 etc.). As you can see, it gives you two gears lower than your current set up, and the top gear of 44 x 11 should still be plenty high enough.

A Spa Super Compact chainset is £69, and their recommended First Components square taper bottom bracket is £14.

Obviously if you don't have access to the necessary tools for removing and fitting a cassette, chainset and bottom bracket, then you will either need to buy the tools or pay a shop to do the work.

[Spinners]

On the final incarnation of the Specialized AWOL I noticed that it used a 12-36 cassette with an Alivio RD and Sora 3000 shifters. I'm tempted to try this combo (also with Sora 50/34).

[Grandad]

I'd like to do something similar with the Claris setup on the Orbea Gain. The current block is 8 speed 11-32 and I prefer the idea of a 14-34 if this is available. Main reason is to reduce the jumps between the gears, the 34 is a minor issue but welcome if the mech will handle it. By time the smallest sprockets are usable I am already freewheeling!

Is there a 14-34 block in the market?

[robgul]

I'd like to do something similar with the Claris setup on the Orbea Gain. The current block is 8 speed 11-32 and I prefer the idea of a 14-34 if this is available. Main reason is to reduce the jumps between the gears, the 34 is a minor issue but welcome if the mech will handle it. By time the smallest sprockets are usable I am already freewheeling!

Is there a 14-34 block in the market?

Miche do some odd combinations - together with a "pick and mix" cassette where all the sprockets are separate with spacers. I'm thinking of fitting a max 34 to my Gain (and changing to Tiagra - 'cos I have an almost new chainset) - although I'm not to bothered about the smallest sprocket size ... 14T would seem to be a bit low for pounding along?

Rob

[Grandad]

If I could pound along I would keep the little sprockets but at 83 with AF there's no chance

At my own comfortable speed I can still do up to 60 miles but had to avoid too many hills The Orbea allows me to now do these and so has opened up long lost areas. As a matter of interest I keep a note of where I use the motor and so far I've done 289 non assisted miles and 32 using the motor.

For the non motor bits it would be nice to have the gear ratios a bit closer together.

[Grandad]

Found this on Sheldon Brown

! It is not difficult to customize Shimano cassettes. If you substitute an un-approved cog, Uniglide or Hyperglide, SRAM, IRD, Miche, or some other brand, it will still work, but the shift to/from that cog will probably not be as smooth as a Hyperglide shift normally is. Since people managed without Hyperglide for several decades, this shouldn't scare you off. In particular, if you substitute the top or bottom sprocket, you will only have one shift that isn't HG; shifts to or from the extreme sprockets tend to be less troublesome than intermediate shifts anyway.

Generally, the smallest sprocket needs to be one with a built-in spacer, designed for the top-gear position. While you can't insert or remove a sprocket within a spider module, you can add sprockets on either side of these modules.

For example, if you want a 13-34 8-speed, you can start with an 11-28 -- the stock HG-50 11-13-15-17-19-21-24-28 has a sweet sequence of gears just as it is -- but to use a larger chainwheel or get a lower bottom gear, you might make this modification:

Replace the 11 and 13 with a top-position 13.
Add a spacer and a 34 after the 28. (You don't need to buy the spacer, because you can use the spacer that came between the original flat 13 and the 15.)
Shimano cassettes that don't use spiders have most of the sprockets held together by 3 small bolts or rivets. These are not essential. Their function is convenience, in allowing the cassette to be installed slightly more easily. To make a custom cassette, you will often need to remove the screws or rivets. Just discard them, they are unnecessary in practice.
Some cassettes use screws with a 4 mm hex head. These can be removed with an adjustable wrench.
Some cassettes use screws with a 2 mm Allen head. These are frequently mistaken for rivets.
The easiest way to remove rivets is to grind off the heads where they protrude from the largest sprocket. I generally do this on a bench grinder.

Shimano do 8 speed cassettes in 11-32 and 13-34. If I buy one of each is it reasonable to ask my LBS (who supplied the Orbea) to do the conversion? I am not confident that my spannering is up to that level.

[Brucey]

depends on the intervening ratios as to whether the resultant cassette makes sense or not.

NB some (not all) cassettes have a second smallest sprocket with an integral spacer, in which case it will work as a smallest sprocket, and you just need to ditch the smallest sprocket and fit a larger sprocket and spacer on the other end of the cassette.

For example some CS-HG50-8 cassettes are like this

https://si.shimano.com/pdfs/ev/EV-CS-HG50-8-3072B.pdf

but I'm not sure if the ratios would suit you or not.

cheers