Category Archives: geek

SEMrush or Searchmetrics


SEMrush and Searchmetrics are two well-know Data As A Service vendors in the search marketing community.
Many projects of SEO, SEM and social networks require research and monitoring. The pricing of both Searchmetrics and SEMrush is similar: monthly recurring fees for around $100 for basic features.

Keyword research

Now, one of the key features of these services are providing data about search keywords on the major search engines (Google) in the largest markets.
The data of keywords are typically used to understand the reach and depth of search engine positioning of websites. This in turns allow to map these websites in their category and in relative terms to their competitors.

Benchmark and methodology

In order to evaluate the quality and relevancy of data available at SEMrush and Searchmetrics.
Spearman’s rank correlation coefficient
It assesses how well the relationship between two ordinal variables.
The Spearman’s rho is a nonparametric measure of statistical dependence between two variables
> kws.correlation <- read.csv(“kws-correlation.csv”, na.strings=””)
> plot(kws.correlation)
> attach(kws.correlation)
> cor.test(gwt,semrush,method=”spearman”)
     Spearman’s rank correlation rho
data:  gwt and semrush
S = 14832, p-value = 4.411e-06
alternative hypothesis: true rho is not equal to 0
sample estimates:
> cor.test(gwt,searchmetrics,method=”spearman”)
     Spearman’s rank correlation rho
data:  gwt and searchmetrics
S = 7310, p-value = 0.007778
alternative hypothesis: true rho is not equal to 0
sample estimates:
> cor.test(semrush,searchmetrics,method=”spearman”)
     Spearman’s rank correlation rho
data:  semrush and searchmetrics
S = 2, p-value < 2.2e-16
alternative hypothesis: true rho is not equal to 0
sample estimates:

Rear mech hanger of the Ridgeback Meteor 2004

I found out that all bicycles with gears have a single Aquilles heel. The rear mech hanger of my Ridgeback Meteor has a crack. It is unsafe to ride the bike. The piece is made of aluminium.

Position of the hanger on the bike
Position of the hanger that attaches the chain system to the frame

The store where I bought the bike in London (Evanscycle) cannot locate its reference. Ridgeback does not does not provide the information online nor answer to emails enquiring about the hanger.

I ordered a gear mech derailler hanger on ebay to a French merchant, Alpine Bikers. They do not answer to questions on ebay but they do ship spares made of aluminium.


Reverse rear mech hangers Ridgeback Meteor 2004
Rear mech hangers Ridgeback Meteor 2004
rear mech hangers Ridgeback Meteor 2004 reverse
Reverse rear mech hangers Ridgeback Meteor 2004

If you think of the hanger as having the shape of a seahorse, the replacement piece has a mouth a bit too long. It cannot be attached to the frame for that reason. My local key-maker trimmed some 2 mm off the piece and the trick work: my bike is on the road again.

This is  the result and how it fitted back in its place.

Trimmed Ridgeback hanger
Hanger trimmed by our local key-cutter

There are protectors of derailleurs available that are worth considering for all-terrain bicycles. It you attach one protector to your bike, leave one of its two holes without screw; this way it still protects the derailleur from direct lateral impacts but it would break or twist where one of the screws is missing thus preventing further damage to the frame, which would be fatal to the bicicycle.

Bicycle tyre Schwalbe Marathon Plus

The Schwalbe Marathon are remarkable tires. I think that I inadvertently rode for at least 100 kilometers (in consecutive riding sessions) with a grain of quartz embedded in the tyre.

Schwalbe Marathon Plus tire
Schwalbe Marathon Plus tire with a grain of quartz

According to a friend who regularly enrols in cycling expeditions in exotic countries, the tire is the primary choice for a world-trip because it’s so reliable.

Juvenile swift stranded in Luarca, Spain

A nestling swift (Apus apus) was lying in the ruins of a house at one meter over street level. It didn´t look injured. We did not touch it.

The pictures were taken in the first week of August in Luarca, a seaside village in the north of Spain.

Swift chick Luarca
Swift chick Luarca
Swift frontal closed eyes
Detail frontal closed eyes
Detail of head of swift chick
Detail of head of swift chick

We spent as little time as possible taking the photos. We did not see the parents coming in to feed the chick in the 5 minutes that we stood waiting at a safe distance.

The first fledgings show up around July 27th in Asturias, Spain, upon the phenology records. There is a great guide to take care of fallen chicks: Swift First Aid.

First arrival dates of swifts are a popular phenology record. Swifts in London arrive in April and May. I think that the duration of stay for Common Swift presence on the nest is a more interesting metric than the first arrival. Surprisingly, this metrics is still poorly studied in Europe (Tigges, U., 2007, The Phenology of the Common Swift Apus apus in Eurasia and the Problem of Defining the Duration of their Stay).