Cassette Change - a Review and Improvements?

I wrote a few weeks ago about the decision to "Man Up" and get a 12-25 cassette for my Giant rather than replace it with either a 12-27 or a 12-28. The reason was really to try to stop being lazy and force myself to use a higher gear and build some strength. Internet cycling forums (fora?) are full of advice about how to ride ("spin" or "grind", "the power is the same", "destroys my knees" etc), but ignoring all this I felt that with the 27 and 28 cassettes I bailed out too soon and looked for a lower gear which I then hung onto for too long meaning that my speed was lower than it might be. There was no real evidence to suggest this, and being an engineer evidence is crucial, but it seemed plausible. So I went ahead and fitted a 12-25 to my Giant.

Since then, when riding the Giant I have also made a concious decision to try to be in 1 gear higher than I feel I would have been before. Bearing in mind that from 4th gear on (the 19 tooth) the gearing is pretty much the same across all the 12 and 11 cassettes the difference lies in 1, 2 and 3 - the 3 biggest rings. As a result my main target is to try to keep in or above the 19 tooth ring.  I have also started to "grind" a bit more and stand up to generate lower speed torque.

I have been riding the new cassette for about 6 weeks or so now, and feel that there is a bit of a change for the better.

I think that this might have been seen today when I went out for an early morning run. The weather was pretty good - shorts and short sleeve top (but with arm warmers) and some but not too much wind.

I rode the same route as I had ridden the week before and within 20 minutes or so felt pretty strong and confident of being able to set a reasonable pace. This route is quite flat - about 1500 feet over 47 miles but features a couple of good stretches of flat fat road where even I can push out a good speed.

At Balsall Common I was at average of about 19.6mph and feeling good. I kept pushing hard and at about 30 miles (Little Alne) was still at 19.3mph average. However from this point its generally uphill all the way. Nowhere is particularly steep but its just a gradual height gain - an example is Pettiford Lane -
   
I am 39th on this segment at 3'15''.

I tried very hard to keep the pace up for the rest of the way home and pushed wherever I could but I felt the time slipping away. I didn't dare look at the Garmin to see what was happening and just kept pushing as hard as I could.

The result when I got home was an overall average of 18.9mph for 47.1 miles.

The ride is here:
 

This route was the same as I rode the week before. This weeks performance was 2:29:52 ride time at an average 18.9mph compared to last week where it was 2:39:07 at an average of 17.7mph. I was to say the least ecstatic with the pace. This is the fastest ride this year (even over commutes which at 18 miles can be pushed hard), and about my 7th fastest ride ever - all the faster rides are over 20-28 miles so not only was the pace high the distance was good as well. And I got 19 achievements (although to be fair on that route I had only ridden it 2 or 3 times before so at worst I would have got a 3rd on many of them!)

Can I claim that the different cassette on the Giant has made this improvement? Probably not as there are other factors.

For example with the better weather and work commitments in my favour I have been able to commute twice a week for the past 3 weeks or so, and been able to extend the Friday return leg to get over 40 miles on the day, and adding this up has given me 4-5 weeks at 100+ miles a week so I am obviosuly a lot fitter now than a few weeks ago:

Regardless I'll take the ride as a memorable PB.

And I am happy with the cassette choice.