GPS device calibration - how does my Garmin 310 XT fare against an "official" distance and time?

I cycled a 100km "sportive" two days ago.
It had an "official" route, and the rider numbers had a timing chip on them, so start and finish times were recorded automatically as we (the riders) went through the start/finish arch.
Isn't technology wonderful.

So, like many others, I looked up my performance on Strava.
I found two "whole course" segments had already been set up by other riders.
The "bench marks" I am using are the "official" route I got from the organisers as a TCX file that I loaded into Garmin Connect, and my "official" "chipped" finishing time (all finishing times are published by the organisers, and available for all to see.

The "benchmark" route was 101.77km (from the "official" TCX route, remember).

So how did the "whole course" segments measure up?

This one comes in at 100.5 km, so sounds right to someone without the "official" route TCX to compare it to - indeed, the rider might have taken a great "line" on every corner and come in just a touch under the "official" route length, so it could be right.
And the time?
It's knocked 7 minutes and 20 seconds off my "official" finish time! It clearly is not measuring all of the route, or the rider took a shortcut (!), or the GPS errors mean it has rounded off some corners etc. etc.
Verdict: Someone has a smartphone (?), and they just chose a section that sounded about the right length.
Update: A route analysis shows that the route start on a straight section on the main road. Useful for perhaps longer training, without having to go down the road to the stadium, but with about a km clipped of the start and end of the "official" route, it is clearly NOT the entire route! The missing couple of kilometres seems to explain the missing time as well.

Mermaid (and I!) clock up our third ever "century" on the Tour de Vale

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StravistiX analysis of my HRM data for the Tour de Vale.
A good part of the Zone 1 bar is the slow "warm-down" I did after the event

Strava's "official" printout - I reached a new peak Heart Rate for cycling (of 174 bpm).
You can see the slow warm-down very clearly on the Heart Rate trace!
There was some waiting about during rider registration at the start,
as well as medal and certificate collection at the end.

My official finishing time (for the 100 km course) was 5 hrs, 22 mins and 55 seconds.
More to follow, after I have had a good rest!

The organisers have a facebook page where you can see some of the folks taking part, including some of the disabled "handbikes" some riders used for the event.
There is also an official list of "finishers" here, but the times for the 25km, 60km, and 100km routes are all mixed intogether, so don't assume the quickest (or slowest!) are doing a particular distance!

Update: some pics from the ride - I started off with Anna's camera in my basket, but it malfunctioned just after Chesham. Later I started using my smartphone for some more pics (but they are likely to be not as good, because the "proper" camera takes much better pics than a cheap smartphone!

Anyway, here are the pics from "home" to Chesham!

Me, all kitted up for the ride.
I planned a "no-stop" strategy, so I am carrying 4 litres of water, plus various foodstuffs, and tools etc. etc.
Naturally, I am wearing my trademark jeans and check shirt.
Note the prominent first-aid kit attached to the top of my rear carrier
- I'd hate to bleed to death just because someone can't find my first-aid kit!
Also ready for use to help other folks!

Buckingham Bikes (our LBS) had a stall for any last minute repairs before the event.
I daren't show them Mermaid, they'll have a laughing fit or a heart attack, or both :-)

Waiting for the start - the blue arch is the actually "start".
The rider numbers have "timing chips" in them, that activate as we go through the arch.
Very classy.
I seem to be the only one with significant luggage (mine weighs 11kg, all up for two panniers and the basket).
I am riding "super tourist" style, but almost everyone else seems to be in "cycle" kit, and riding "road".
I may have had both the cheapest AND the heaviest bike for the 100km!
Just before we started the announcer asked all thouse who had done a 100km before to raise their hands - not many of us put their hands up ...

Final Preparations

Making a list, and checking it twice ...

Tomorrow is the Tour de Vale, and I'll be doing my second "century" of 2015 (and, actually, only my third "century" ever!).

So this evening, I am gathering up the stuff I'm taking.
I'm carrying a lot of kit because I am not intending to make any proper stops - perhaps just a quick stop for the restroom and to re-arrange my water bottle, but that's it.

I'm looking to set "a time", rather than just "complete", so I want to keep going.

My "secret weapon" is my Garmin 310xt watch, which I will be setting up with a heart-rate alert of about 80% of my maximum heart rate. I'll be trying to conserve my strength for the later parts of the route. I tested the route 4 weeks ago, and I found I faded badly on the last third of the course :-(
So this time, I'll be looking to "save" myself a bit more on the early sections.

Of course, on the early hills, the "high heart rate" warning will be beeping constantly, and I will be getting up towards my maximum heart rate on the biggest climb (!) but if I can save most of my glycogen for the hills, and use the "aerobic" part of my metabolism for most of the rest of the ride, I should fare better.

I have a slightly lower "bottom" gear than in last month's "test", as well - I swapped the smallest chainwheel from a 28 to a 26.

I'm not much of a fan of pricey bikes and pricey sports drinks, so I made my own ...
On the "test" ride, I took water with half a teaspoon of sugar and a 1/4 teaspoon of salt per litre.

This time I have gone for a strong blackcurant "aquash" drink, with about 1/4 teaspoon of salt per litre added - the stuff works out at about 280 calories a bottle, and contains about 70g of carbohydrate (mostly sugars) per bottle ...
... and I have three bottles!

Homemade sports drinks - a strong-ish mix of "squash" with a bit of salt added.
A diabetic's nightmare at about 70g of carbohydrate (mostly sugars) per bottle!

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Of course, I am carrying quite a bit of "regular" water as well - a good couple of litres, in fact.
Various food stuffs mean I am carrying at least 2000 calories of food and drink with me.
On the "test" ride, I burnt off about 2500 calories, so I want to make sure I ahve enough for the whole trip.

Apart from food, I've been finding the stuff everyone forgets about - suncream and hay fever tablets, for example, as well as collecting up some tools, a spre tube, a puncture kit and tyre levers, a couple of cans of tyre repair foam etc. etc. (and remembering that I have Marathon Plus tyres, I shouldn't need ANY of that stuff!)

I also did a map for my wife with pre-arranged meeting points, and loaded some tools and spares into the car (if needed, she is also my "service car" AND "broom wagon").

I found my first aid kit (it is a small one in a red pouch), and attached it to the TOP of my rear pannier rack - nice and visible in case of emergency. Sometimes every second counts, and it would be a pity if a passerby was unable to find my first aid kit at the bottom of a pannier (!)

One last thing reamins to be done - getting a good night's sleep.
Sleep is an important part of the training process, and starting a ride well rested gives a rider a real boost in the second half of a long ride!

Sponshorship link for anyone interested:
https://www.sponsorme.co.uk/petermilsom/bhf-london-to-brighton-bike-ride-2015.aspx
The two charities are
1) The British Heart Foundation - a large national charity that funds reseach into matters heart conditions, disease, etc. etc.
2) Wheelpower - a much smaller charity based in our town that funds a variety of aspects of disabled sports, including funding special wheelchairs for disabled children to participate.

New Front Wheel

Of course you can move a bike wheel on a bike!

I bought a new front wheel today.
Mach 1 240 rim (that's heavy-duty!) with 36 spokes.

The previous front wheel on Mermaid (the original!) has lost all signs of the "wear" grove on BOTH side of the rim!

The final straw was a broken spoke picked up while on the rather worn-out roads that form the basis of next Sunday's "century" ride - I tested the route a few weeks back, and just let me say that anyone who is doing the event on fancy lightweight wheel might get a bit of a surprise!
I could have just replaced the spoke, but the rim really should have been replaced some time ago (!), so I went with a whole new, machine-built, wheel.
Mermaid has only ever had modestly priced machine-built wheels, so this wheel is actually an upgrade (the new rim has a box-section, compared with the single-wall construction of the original)

Just got to fit it now.

Bit of service work on the bike

Can you see what is wrong?

I like to ride.
I don't much want to spend all my time fixing my bike, I want to spend all my time riding it!
Sometimes, though, a bit of maintenance is needed.
I have a "Century" ride coming up on Sunday, so I gave the bike a quick lookover last night.