cassette for Dawes Super Galaxy 2011

[timdownieuk]

If my experience with Dawes is anything to go by the cassette on your bike may not have been an 11-32 but something else. My Horizon was supposed to have 11-32 but had 11-30 and my Century was supposed to have 12-25 but has 11-25.

This has to be the explanation. I know what the new cassette is because I've counted the teeth and the serial number is on the smallest ring. I didn't check what the old cassette was, I'm just going on what I can see online.

I took the bike in for a service because it's done nearly 4000 miles. I can't fault anything else, it's beautifully smooth and clean. He did ask me if I wanted a different cassette, one with easier ratios. I said no, because the existing one was perfect. I can get up any hill fully loaded, so it's low enough, but the top end is really good, had 50 mph out of it. Now my legs are flailing around at 25mph. And I'm in a much higher gear just going along on the flat. The front mech rings haven't been changed, just a new chain and cassette. And I do know what gear I'm in and it's not due to the wind, credit me with some intelligence!

I'm having a big problem squaring the statements "the top is (was) really good, had 50 mph out of it" and "flailing around at 25 mph" without there being a huge change in gearing, not just a one tooth difference in top gear. We know that the new cassette has a 11 tooth sprocket for the highest gear now. To achieve what you claim to have achieved before would require the old one to have had only 5 or 6 teeth!

Now I appreciate that a bit of exaggeration may have crept in but in the words of Scotty, "You cannae change the laws of physics!"

It just doesn't make any sense.

[fatboy]

It's not to with the cycle computer is it?

[OnYourRight]

It's not to with the cycle computer is it?

A guess in this direction: it was previously set to km/h although patpalloon always believed it to be reading miles per hour, and the bike shop changed it to actually read in miles per hour. Getting it to show 25 would therefore require ~1.6 × faster pedalling in a given gear.

None of these suggestions square up with patpalloon’s considerable experience as a touring cyclist, but there’s no easy explanation for a massive change in gearing without an accompanying massive change in the number of sprocket teeth. In fact I can think of no rational explanation.

Which leads me to a question, patpalloon: what are you thinking of telling your bike shop?

I hope you get to the bottom of this, regardless.

[mercalia]

summer is the silly season for news paper stories?

[patpalloon]

Thanks for the suggestions, but saying things like I might have be speedo calibrated wrong, or have I looked down to check I'm in the right gear aren't really very heplful. I am an experienced cyclist and I have done 2 UK end to ends on it supported, 700 miles in Spain and 950 miles around Ireland on it unsupported and loaded. And before you say it, no it's not different because I am now riding it unloaded. My speedo is a Garmin gps set to mph.

I know my bike and the ratios are different now. The only explanation I can think of is that the original cassette was not the onelisted by Dawes, unfortunately I don't have it now. Ok let me explain the 50mph statement. I have had 50 mph downhill, but that was freewheeling. Generally I don't need the big chain ring at the front until above 25mph and that's probably 7th at the back giving me two more gears to change up. But at the other end I can get up any hill even fully loaded so it was perfect.

The bike is going in on Monday. I hope they have a record somewhere of the cassette that was taken off.

[timdownieuk]

Thanks for the suggestions, but saying things like I might have be speedo calibrated wrong, or have I looked down to check I'm in the right gear aren't really very heplful. I am an experienced cyclist and I have done 2 UK end to ends on it supported, 700 miles in Spain and 950 miles around Ireland on it unsupported and loaded. And before you say it, no it's not different because I am now riding it unloaded. My speedo is a Garmin gps set to mph.

I know my bike and the ratios are different now. The only explanation I can think of is that the original cassette was not the onelisted by Dawes, unfortunately I don't have it now. Ok let me explain the 50mph statement. I have had 50 mph downhill, but that was freewheeling. Generally I don't need the big chain ring at the front until above 25mph and that's probably 7th at the back giving me two more gears to change up. But at the other end I can get up any hill even fully loaded so it was perfect.

The bike is going in on Monday. I hope they have a record somewhere of the cassette that was taken off.

Most of us don't know you so we can't assume experience. Or rather we can but if we do that we risk overestimating a rider's experience/knowledge which can lead to confusion sometimes. You didn't help us to help you by adding irrelevant details like your freewheeling speed downhill!

We can only work with what you tell us and what you told us didn't really make much sense to many here.

[OnYourRight]

But it still doesn’t make sense. The top gear you had before could not have been higher than 48T × 11T, the same as it is now.

Only if your previous cassette had fewer than 11 teeth on the smallest sprocket could you have had a higher gear. Such cassettes don’t really exist and certainly wouldn’t be shipped on a Dawes tourer.

Your intermediate gears may have changed with the new cassette, but we’re talking about small changes – a tooth here or there.

[patpalloon]

I see your point, so there's nothing smaller than an 11? Perhaps I didn't make myself clear on earlier posts and got to hung up on the highest ģear. Before I would be on the middle chain ring at the front for most of the time. I would be in 4th to 7th at the back. This would do for 90% of my riding. I would only need the smallest chain ring at the front ie the granny, for steeper hills - using 1st to 4th at the back. I would only need the big ring at the front for downhills and then 7th to 9th at the back. I tended to stick to these so as not to cross the chain.

Now, I'm having to change up to the big chain ring at the front a lot more, and down again to the middle, so this is going to out more strain on my front mech, cable etc. I hope this makes sense.

[531colin]

No, it still makes no sense at all.
You had 11-32, or thereabouts.
You now have 11-32, or thereabouts.
Look at the individual tooth counts here....http://www.sjscycles.co.uk/shimano-deore-hg50-9-speed-cassette-11-32-prod8136/
.....11,12,14,16,18,21,24,28,32 ....just as an example
take the middle sprocket, 18 teeth, and my guess that your chainrings are 26,36,48.
48 front, 18 back gives a 72" gear....a good sensible middle gear for lots of people.
You can't get exactly 72" from a 36 tooth front, a 14 tooth gives 69" and a 13 tooth gives 75"
But you can't get either a 13 or 14 tooth sprocket in the middle of a 9 speed 11 to 32 cassette.

[fatboy]

It wasn't a SRAM cassette before? For 8 speed at least the graduation is different with bigger gaps at the bottom and smaller higher up. I've had both and yes they are different, but I'm fine with both

[531colin]

It wasn't a SRAM cassette before? For 8 speed at least the graduation is different with bigger gaps at the bottom and smaller higher up. I've had both and yes they are different, but I'm fine with both

But any differences will be small.
Shimano example is 11 12 14 16 18 21 24 28 32
SRAM won't be ...... 11 12 13 14 15 16 20 25 32
48x21=62"
36x16=60"

Using sensible differences between sprockets, you can't make a big enough difference in the cassette to equal the difference between chainring sizes.

[PT1029]

Patpalloon,
as per my previous post, can you definitavely say what psi you pump your tyres up to?
As with all the other respondents, your otherwise mechanical explanations mystify me!

[patpalloon]

I always keep my tyres at 80 psi. I haven't changed the tyres or wheels. The new cassette is a Shimanos CS HG80 9 speed 11 32. I don't know for definite what the old one was. It was a 9 speed. I'm taking it in on Monday so will let you know what happens.

[nez]

If you took your galaxy to a good shop, they probably doubled the tyre pressure to where it should have been!

I hope that isn't a rule, I keep my Super Galaxy at 120psi!

[patpalloon]

120 psi is very high for touring bike tyres. What tyres are you running?

And more to the point, what cassette do you have on your Super Galaxy? And what year is it?