Advice needed for new gears

ANT 666

Trying to re member
You would be pushed to get a biopace ring now any way, a round one will be a straight swap, you just need to make sure its the right bolt pattern, its probably 130 bcd.
A 30tooth rear cassette again no worries there,and any 7 speed will be good.
As for retailers loads I've used a dozen or more all seem much of a muchness to me, never had any bother with any one, or off ebay. Just stick what you want in a search engine and shop around for the cheapest thats what I do!


You will struggle to get a 7 spd with a 34t. Even if you find one it will be a horrible big step up from next sprocket with only 7 of them making gear change very clunky. You could do with a 7spd rear mech with the really big jockey wheels to get it to work.


Über Member
[QUOTE 3581372, member: 9609"]I have found this one LINK
(so it is a half way house between the 28 now fitted and the 32t that are widely available)
Does this sound a reasonable replacement?[/QUOTE]

That looks the biz should be good, so are you putting new chain rings on as well....?. I would also get new jockey wheels while you're on.

Pale Rider

Legendary Member
In my limited experience, a couple of extra teeth at the back won't make a lot of difference.

You may find otherwise, but my suggestion would be for a smaller ring at the front as well.
@User9609 Changing the front to a 38th (providing the FD can do 14th, I presume the large ring is 52th) a 38x30 gives a 1:1.27 compared with 40x27 of 1:1.48 which is about 15% or about 6 gear inches, which will make a big difference, I notice the difference between a 6" and 3" gear change, on my set up for example 38x17 to 19 or 38x17-18-19 the difference between 17-19 is 6.2" 38x17-18 is 3.3" and 38x19 is 2.9" so if I can notice that you will notice a difference in 6", another option is to get a compact crank, one with a 110BCD and some new rings (though a new BB would most likely to be needed) I don't know what high gear you need so can't give an idea of what is needed. You could then fit smaller chain rings (down to 34), I would normally advise a triple many people don't like them, but it is a significant change, needing new shifters ect... the reason is you retain the normal double like you have and a low range, also the benefit of a close grouped cassette, i.e. a 30x23 is a 1:1.3 the same as you looking at but also the 13/14/15/17/19/21/23 option making the changes much closer on the back, depending on you shifters it may be possible to do this by just changing the left from a double to a triple, changing the FD and chainset/BB, a triple chainset can be had for £35 with 28/38/48 set of rings, bb £10-20, FD £10-20 + the shifter, gearing options are endless.


Über Member
[QUOTE 3581499, member: 9609"]Is there any compatibility issues between the shimano HG variations, ie HG20, HG50, HG70 etc ?
and I take it all these cassattes fit the freewheel hubs ?

The front small chain ring is knackered, so will be replacing (i never use the big ring)
Why do you suggest new jockey wheels, ?[/QUOTE]

There shouldn't be any compatibility issues, the HG stands for hyper glide which means with that designation they would all be compatible and yes they will fit onto the same freehub.

Everything wears together if your replacing the cassette, chainrings and chain, it would be wise to replace the jockey wheels as well as the new chain will probably not ride on the worn ones as good and affect shifting.
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^^^^What he says inner ring £10 middle £15 outer £20 these are there own branded zircal rings (they look pretty good too), there is however £5 p&p on orders less than £50.
As new
after 3,500 miles
The inner is just standard dural ring, but its not used often in normal riding. The cranks are £20 plus a 113mm bb, it is a standard compact triple ( compact chainset is defined by the BCD and not the size of the number of teeth on the rings as many believe) A compact double has a bcd of 110mm and the lowest ring you can fit is 34th the triple above has the 11bcd with an inner of 74mm bcd which I believe will go down to 24th, I run a 26/38/50 12-27 cassette.
The formula for working out gear inchs is the ratio x the diameter of the wheel is wheel diameter in inches x(teeth on the front chain ring/teeth on the rear (or the ratio))
i.e. 700x23c is 668mm 26.3" so for a 39/30 it would be 26.3*1.3=34.2"
Sheldons gear calculator
[QUOTE 3586314, member: 9609"]Indeed, I have just seen what I did above - for whatever reason (maybe I was tired) I used circumference :wacko: I thought the figures were high[/QUOTE]
Should see the mistakes I make when I am tired :laugh:
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