Cassettes - Shimano V's SRAM - Gearing

Manc33

I recently got hold of a Rockrider 6.2 and it is all very well except I noticed at cruising speed (about 10 MPH to 15 MPH) it seems impossible to find the right gear at that speed. There are quite big differences between the cogs!

This bike came with an SRAM cassette, described in the spec as a:

"K7 SRAM 5.0/ 11 x 32/ 8 speed cassette".

You can see in this image the big jumps between the cogs:



I don't like it like this at all - then I wondered why the hell have they put a SRAM cassette on a bike with a Shimano rear mech?

I went looking (just online) at the Shimano 8 speed cassettes and its quite hard to get hold of 8 speed stuff now but I have seen one that LOOKS like it does not have those massive jumps between gears - the Shimano HG50:



I can see right away that the Shimano cassette has a way better setup for the cog spacings! Look at the SRAM then look at the Shimano, look at the big jumps on the SRAM where the Shimano really has no big jumps.

I have heard someone say "its because your biggest cog on the back is a 32 tooth cog" but that is actually not true because like I said before the "big jump" on the cassette is somewhere around the middle like #3/#4/#5 cogs. The big 32 tooth cog is way bigger than the next one down but thats not where the big jump feels like it is. It is around the middle, slap bang in the middle.

The other option is to just use the biggest front ring but thats not really useful to me.

The SRAM cassette is as far away from close ratio as you can get, I actually hate it and as soon as I get the money I am swapping it for a HG50.

There is only one down side to this - the Shimano HG50 cassette weighs something like double what the SRAM weighs... the thing is I don't care really, I want a cassette like the old 5 speed ones where the cassette looks like a "pyramid" if you know what I mean, as opposed to a curved pyramid where it seems to have 4 small cogs and 4 big cogs with a jump between #4 and #5 cogs.

Shimano HG50 can be had for about £17 if you shop around. Yes it weighs a lot, but look at the images above, its there for your eyes to see.

I am actually going to count the teeth on that SRAM and work out exactly the gearing.

mrfmilo

If you want less of a jump between shifts, closer ratios and higher gears (plus less weight), get a road cassette - however you may find the ratios are too close/high.

Da Mighty Chicken

unless my eyes are deceiving me, the pic of the SRAM cassette is a 7 speed?

Almightydutch

Da Mighty Chicken wrote:

unless my eyes are deceiving me, the pic of the SRAM cassette is a 7 speed?

Yeah i had to look twice on that one.

nicklouse

so what are the number of teeth on your current cassette?

and how does that compare to the shimano one?

careful you dont get the same.

the HG-50 can be from the "MTB" range

11 – 13 – 15 – 17 – 20 – 23 – 26 – 30T
11 --13 --15 --18 -- 21 -- 24 -- 28 -- 32T

and from the "road" range

12 --13 --14 --15 -- 16 -- 17 -- 19 -- 21T
13 --14 --15 --16 -- 17 -- 19 -- 21 -- 23T
12 --13 --14 --15 -- 17 -- 19 -- 21 -- 23T
13 --14 --15 --17 -- 19 -- 21 -- 23 -- 26T
12 --13 --15 --17 -- 19 -- 21 -- 23 -- 25T

mrfmilo

And ratios have got nothing to with companies ie. SRAM / Shimano. They've all got different ratios, you've got to choose which you want.

Manc33

Sorry yes I posted a 7sp SRAM cassette there

Here it is:



It looks just like that 7sp in the first post.

I just worked out all the "jumps" between all the cogs:

SRAM 8 Speed Cassette

32/26/21/18/16/14/12/11

Gear jumps going from smallest cog to biggest:

11 to 12 = 9.0% (#1 to #2)
12 to 14 = 16.7% (#2 to #3)
14 to 16 = 14.3% (#3 to #4)
16 to 18 = 12.5% (#4 to #5)
18 to 21 = 16.7% (#5 to #6)
21 to 26 = 23.8% (#6 to #7)
26 to 32 = 23.0% (#7 to #8)

To work out equal gear ratios lets take the total difference in teeth from 11 to 32 = 21 teeth in total. So if you had a cassette with 8 cogs and the smallest cog is 11 teeth...

Total teeth (21) divided by (8) cogs = 2.625

This means each cog should "jump" up about 2 or 3 teeth, but this is the WRONG way to
work it out!

Whats needed is to find the total percentage, but that is impossible (or extremely hard to
figure out since as each cog gets exponentially bigger, the percentage is no longer the same on the next cog up. Going from #1 to #2 is X percent but then what about the rest lol?!

You'd have to work it out the 21 tooth way, or just have your cogs set so the overall difference is divisible by 8. That leaves you with a 24 difference - impossible, because 11-32 is the limit. Cannot go smaller than 11 or bigger than 32.

Maybe some 8sp road cassette could be the way to go, the one with the biggest difference between smallest and biggest, like the one posted above:

12/13/15/17/19/21/23/25

This however would give me a dilemma since even with a 11T cog the highest gear is still too low. Thats because my biggest front chainring is a 42T (WTF!) I see some ate 44T and 46T and even 48T.

I have got a Silverlight chainring set here for a road touring bike, it has 3 rings and the spacing looks the same. This would be ace on that bike because its 28/38/48 as opposed to 22/32/42 and would take all my gears way higher, but I think I can't be bothered to be honest lol... its a big job changing a chainset I don't think it will fit anyway, shame because it weight bugger all. Well the other thing is its aliminium which I know won't last (I remember the old Shimano Deore BioPace shainrings I had ended up so worn out the chain slipped... thats it folks once that happens you have a destroyed ring) so I am reluctant to even put an aluminium one on it.

I am skint but ideally I would just throw a whole LX or even XT setup on it, well maybe just upgrade the awful Altus rear mech to a SLX or XT, put an XT 8sp cassette on (with every cog chosen specifically!) and a more realistic chainset setup like 24/34/46 as opposed to the silly-low 22/32/42 lit has now.

All in all though I am not complaining about this bike, for the money (£260) it is hard to top, its just those pesky gear changes and yeah, the Altus is quite a nasty rear deurallier, coming close to Tourney spec there... the Alivio is the best in that "A" range of Altus, Acera, Alivio. It goes in that order as far as I know.

The thing is this has a Shimano rear changer with a SRAM cassette - surely this setup is never going to change gear as well as it would if the cassette were Shimano? :?

Damn, what I really want is a Rohloff 14 speed internal hub but they are £1200

mrfmilo

Bloody hell, longest post ever :shock:

What are you trying to ask?

peter413

Couldn't fully understand that but I think you are wanting to change your rear mech and cassette and crankset.

Why not just get some new shifters as well and go 9 speed then, you can have closer ratios then

And no, the shimano and sram cassettes mechs are completely compatibly, the only thing you can't mix is rear mech and shifters, must be shimano/shimano or sram/sram.

It all works perfectly fine together apart from that

nickfrog

Stop typing. Go riding.

Manc33

LOL I think I have worked it out.

As I added up the percentages then divided by 7 jumps, it adds up to 116 for a 11-32T cassette regardless of the in between sizes and dare I say it, regardless of even how many cogs the cassette has.

So it works out a 15.4% jump is the AVERAGE jump, if you wanted to keep it as close as you can but keep the gearing reasonably low, I reckon this setup:

24-34-46
11-12-13-15-17-20-23-28

You then have a lowest gear of 1 turn of the crank = wheel turns 0.86 times and a highest gear of 1 turn of the crank = wheel turns 4.18 times.

Currently my highest gear the wheel turns 3.82 times... it is all wrong on the road.

You CAN have the best of both worlds I think!

What I want is a set of gears where:

1. There is a low gear, under 1:1 (like above, 0.86)

2. There is a nice high gear for pedalling over 30MPH - just to get a boost down hills on the road. My current setup has me pedalling as fast as possible at about 25MPH in the highest gear, basically I run out of gears!

3. Needs to be EQUALLY SPACED OUT. None of those big jumps!

8sp is bloody awkward and yeah if it were 9sp that would be far easier to work out, the first 3 smallest cogs would be 11/12/13 then 15/17/19 then 22/25/28 that is as straighforward as it gets. cogs 1 to 3 it steps up 1 tooth, cogs 4 to 6 it steps up by 2 teeth then cogs 7 to 9 it steps up by 3 teeth. With that setup you haven't got any big jumps and you have the all important high AND low gears. I don't care about overlapping ratios as much as having equally spaced changes, yes even on the dirtiest tracks, this close ratio stuff is not exclusive to road bikes, IMO they have gone too far with it now and the ratio is screwed up on that SRAM cassette.

Surprised no one has said get a single speed yet. :P

I am gonna ride it today don't worry

mrfmilo

If you are spinning out just get a different ratio cassette! No poing working it all out...which doesn't even really work.

peter413

Or just get a bigger chainring :roll:

mrfmilo

peter413 wrote:

Or just get a bigger chainring :roll:

Yes, or that.

Manc33

This shows the crazy amount of shuffling around changing gears you would need to do to change through all the gears smoothly, LOL smoothly he says...

S = Small Front Chainring
M = Middle Front Chainring
L = Large Front Chainring
1 = Largest Rear Cog
8 = Smallest Rear Cog
Last Number is the wheel revolutions for one full turn of the pedals

S + 1 = 0.69
S + 2 = 0.85
M + 1 = 1.00
S + 3 = 1.05
S + 4 = 1.22
M + 2 = 1.23
L + 1 = 1.31
S + 5 = 1.38
M + 3 = 1.52
S + 6 = 1.57
L + 2 = 1.62
M + 4 = 1.78
S + 7 = 1.83
S + 8 = 2.00
M + 5 = 2.00
L + 3 = 2.00
M + 6 = 2.29
L + 4 = 2.33
L + 5 = 2.63
M + 7 = 2.67
M + 8 = 2.91
L + 6 = 3.00
L + 7 = 3.50
L + 8 = 3.82

Even Einstein could not remember all that. :!:

supersonic

What is your cadence? Knowing what cadence you prefer, and speed, you can work out what gearing suits you best.

10-15mph is a 50% jump though, much more then any of these gearing jumps. I am suprised you can't settle on one you like with your cassette.

Anonymous

Manc33 wrote:

This however would give me a dilemma since even with a 11T cog the highest gear is still too low. Thats because my biggest front chainring is a 42T (WTF!) I see some ate 44T and 46T and even 48T.

---

There is a nice high gear for pedalling over 30MPH - just to get a boost down hills on the road. My current setup has me pedalling as fast as possible at about 25MPH in the highest gear, basically I run out of gears!

Erm, I'm sorry, you appear to be in the wrong forum and on the wrong bike.
I think you'll find this is the MOUNTAIN biking forum.

If you want better on-road performace, why not ditch the fat tyres, and fit some narrow slicks, you could even put bigger rims on it to increase gearing, and maybe make those rims narrower to save weight.
Then maybe you could fit a lower handlebar to increase aerodynamics, since at 30mph+ that kind of thing becomes important.

Sounds like you need the devil's horse... a ROAD BIKE :twisted:

snotty badger

You surely can't be properly off-road if 42-11 spins out?!

I think you're putting too much thought into the whole ratio thing! I've just taken off a 9spd HG50 and by god it's heavy!

nickfrog

Manc33, you do realise that some of those combinations are NOT possible I hope ? (like S+8 or L+1 for instance).

Manc33

Yeah I put the L + 1 in red S + 8 is possible, but noisy lol. :oops:

I want a bike to go on both the road and trails.

I never agree with the usual arguments:

1. "You can't have both"
2. "You don't want full suspension"

Important to point out I said "want" suspension not "need". No one needs air conditioning in a car, it has opening windows and it moves - but having air con is NICE! It is the same with me and suspension.

People argue that even on a track you don't need suspension while my argument is that I know personally how bad some bumps are in the ROAD around where I live (North West England, not a third world country lol) and yes, I know there's always the added weight and pedal bob, but I don't care and want full suspension even on the road, I want comfort.

The first point is about how you can't have a bike thats extremely good on the road and extremely good on the track, yes a real road bike would shatter apart, the wheels would be more untrue than Tony Blair if you slammed a road bike down a rocky dirt track... on a MTB on the road you don't have that to worry about but you do have real bad drag from the fat knobbly tyres and how you're sat upright, the weight isn't really that much of an issue when we are talking about downhill on the road.

So my argument is that if you get a wide range of gears and get the ratio nice and close (ish) on the cassette, with tyres just like this Rockrider has (they are like a hybrid tyre) then why don't you have a "go anywhere" bike?

Thats all I want, a go anywhere bike or, all terrain - which includes roads lol how would I even ride to the track

Everyone would argue "then all you have is a bike that does NOTHING WELL" and thats is true, I know, but the aim is a bike that copes with anything.

After all this typing I will probably leave it as it is lol, but the figures are all there for anyone interested. :roll:

Anonymous

Manc33 wrote:

I want a bike to go on both the road and trails.

Well you're going to have to compromise then.
You really CAN NOT have the very best of both worlds.

Which way you aim your compromises is for you to decide.

unixnerd

I run a Shimano 11-28 8 speed on my Marin and don't find the gaps are too bad, but getting one at a sensible price wasn't easy. Ended up buying on ebay from a guy in Italy, still loads cheaper than the UK. It was an HG70 I think.

Manc33

unixnerd wrote:

I run a Shimano 11-28 8 speed on my Marin and don't find the gaps are too bad, but getting one at a sensible price wasn't easy. Ended up buying on ebay from a guy in Italy, still loads cheaper than the UK. It was an HG70 I think.

Is the higher price because it is 8 speed? Or because a 11T to 28T cassette is a rare thing? Maybe both huh. The worst thing about my bike is how it is 8 speed, but im not complaining really, I knew the price of it meant I was only going to be getting the basics/old stuff.

nickfrog

You can't have both. You seem to know next to nothing about cycling, yet you give lessons to people who know a great deal about it. Very tedious.
Go and learn to ride a bike.

unixnerd

Is the higher price because it is 8 speed? Or because a 11T to 28T cassette is a rare thing? Maybe both huh. The worst thing about my bike is how it is 8 speed, but im not complaining really, I knew the price of it meant I was only going to be getting the basics/old stuff.

I think the 8 speed stuff is getting harder to find in the better grades of component. I could have sourced a lower end part much more easily, but the bike is XT throughout and I want to keep it to a high spec.

It's a '97 Marin Mount Vision (superb bike, really light). I could have gone to 9 speed but I'd have had to change quite a lot to do it and the bike is so original and in such good condition it'd have been a shame. I'd like closer ratios but not enough to change the rest of the bike. The gaps in ratio I have at the moment are quite acceptable to me.

My tourer is about 7 years old and runs Sora with an 8 speed 11-32 (or 34?) rear end. I find an annoying gap between the top 4 and bottom 4 gears. If I used it more I'd have no hesitation in going to 9 speed. But I only use it in bad weather when my nice 9 speed Cannondale road bike it hiding from the elements.

peter413

You only need to change the rear shifter pod and obviously the chain and cassette, you should change the chain when you change the cassette anyway

Mr Wu

nickfrog wrote:

You can't have both. You seem to know next to nothing about cycling, yet you give lessons to people who know a great deal about it. Very tedious.
Go and learn to ride a bike.

Good point. Well put.

I'm just re-reading it all again in the hope it'll get me off to sleep.

Manc33

Well don't lose any sleep.

Can I put a road cassette on a mountain bike?

Since I know "next to nothing" I hope someone can answer this.

It is a 8 speed. I don't see why not. Would the rear mech also have to be changed? Say it aint so!

I was thinking a 11 to 23 would be nice.

If you have a 22-32-42 setup on the front, the lowest gear would be 22F/23R or 0.96, this is pretty much as low a gear as ANY bike needs! The problem always is my gears are too low, the whole range. If a hill is so steep that pedalling is too hard even at 0.96 then id get off and walk, Jesus.

You still retain the 11 cog because its a 11-23 cassette. Ideally I would love it if it was 11 to 21, but with 21 you can't have that low gear and I think its needed.

Then, you have a close ratio cassette with 11.12.13.14.15.17.19.23

Yes! This is the start of my dream to make the perfect drivetrain!!!

As long as that type of cassette fits on a MTB frame?!?!?!?!

With this setup, you would be using the smallest and middle chainring a lot, the big chainring would only come in at high speed.

22F - 23R = 0.96
22F - 19R = 1.16
22F - 17R = 1.29
22F - 15R = 1.47
22F - 14R = 1.57
22F - 13R = 1.69
22F - 12R = 1.83
22F - 11R = 2.00

32F - 23R = 1.39
32F - 19R = 1.68
32F - 17R = 1.88
32F - 15R = 2.13
32F - 14R = 2.29
32F - 13R = 2.46
32F - 12R = 2.67
32F - 11R = 2.91

42F - 23R = 1.83
42F - 19R = 2.21
42F - 17R = 2.47
42F - 15R = 2.80
42F - 14R = 3.00
42F - 13R = 3.23
42F - 12R = 3.50
42F - 11R = 3.82

nicklouse

there is no such thing as a MTB cassette there are wide range and close range cassettes.

the former tend to be found on MTBs and the latter on Road bikes but not exclusively.

as long as the spline pattern matched your hub no probs.

Anonymous

Manc33 wrote:

The problem always is my gears are too low, the whole range. If a hill is so steep that pedalling is too hard even at 0.96 then id get off and walk, Jesus.

Wow, just... WOW! :shock:

Manc33

yeehaamcgee wrote:

Manc33 wrote:

The problem always is my gears are too low, the whole range. If a hill is so steep that pedalling is too hard even at 0.96 then id get off and walk, Jesus.

Wow, just... WOW! :shock:

Why, just why?

With a 22 on the front and 32 on the back (standard lowest gear on most MTB's) thats a ratio of 0.70. You are going at TWO miles an hour on those cogs buddy! You can't even pedal fast enough to make 6MPH hardly = STUPID + POINTLESS. What is the point when walking with it you could be going 4 MPH. When I first got on my bike it was in the lowest gear, I thought the chain had come off. :shock: Nope, it was in the lowest gear, a pointlessly low gear, too low.

The gearing on the crappy old 7 speed I gave up was better! That has a 26F and 28R so a ratio of 0.93. I figured make your lowest gear around 0.90 to 1.00 and there it is, you only need a freaking 23 on the back not a ridiculous 32 :roll:

Of course I only say a 11-23T on a 22-32-42 chainset. That 22 front will get used a lot on hills. Man, it would be far better.

Here is every gear on a 11-32T

22F - 32R = 0.69
22F - 26R = 0.85
22F - 21R = 1.05
22F - 18R = 1.22
22F - 16R = 1.38
22F - 14R = 1.57
22F - 12R = 1.83
22F - 11R = 2.00

32F - 32R = 1.00
32F - 26R = 1.23
32F - 21R = 1.52
32F - 18R = 1.78
32F - 16R = 2.00
32F - 14R = 2.29
32F - 12R = 2.67
32F - 11R = 2.91

42F - 32R = 1.31
42F - 26R = 1.62
42F - 21R = 2.00
42F - 18R = 2.33
42F - 16R = 2.63
42F - 14R = 3.00
42F - 12R = 3.50
42F - 11R = 3.82

With a 11-23T setup:

22F - 23R = 0.96
22F - 19R = 1.16
22F - 17R = 1.29
22F - 15R = 1.47
22F - 14R = 1.57
22F - 13R = 1.69
22F - 12R = 1.83
22F - 11R = 2.00

32F - 23R = 1.39
32F - 19R = 1.68
32F - 17R = 1.88
32F - 15R = 2.13
32F - 14R = 2.29
32F - 13R = 2.46
32F - 12R = 2.67
32F - 11R = 2.91

42F - 23R = 1.83
42F - 19R = 2.21
42F - 17R = 2.47
42F - 15R = 2.80
42F - 14R = 3.00
42F - 13R = 3.23
42F - 12R = 3.50
42F - 11R = 3.82