Saturday, 11 June 2016

Hoppy goes on a diet

Hoppy on a diet. Front mudguard gone, many other bits to follow!

In two weeks I have a 100km charity sportive.
So it is time I put Hoppy on a diet.

The math shows that my time for the sportive will drop by about 1 minute for every kilo (2.2 lbs) of weight lost. (Update: A later calculation suggests that the time saving over the 100km route will be about 48 seconds per kilo lost)

Off my fat butt, I am down about 6 kilos (13.2 lbs) on this time last year.
(And I am about 12 kg / 26.2 lbs down on my weight for January 1st 2015, which is when I started my diet).
So that's 6 minutes saved!

My previous bike weighed in at a rather sedate 18kg (almost 40lbs,)
The Hoprider 300 weighs (according to Decathlon, the place that sells them!), 15.6 kg for a "medium,".
Well, my Hoprider 300 is an "extra large", so is going to weigh in heavier than that! More like 16.5kg.

So I put Hoppy on a diet.
Off came the mudguards (fenders)
Front fender and fittings weigh 230g

Rear fender (and fittings) weigh in at 291g

Off came the kick stand.
182g for the kickstand

Off came the lights.
107g for the front light ...

... and 74g for the rear

Off came the dynamo wheel, and on went the wheel I had on Mermaid, saving 454g just for that change!
The wheel from mermaid weighs 1212g ...

The dynamo wheel that comes with the bike weighs 1666g.

On went some super-heavy (and super-reliable) Marathon Plus tyres - at 791g each, they weighed 124g MORE than the tyres supplied with Hoppy. But the Marathon Plus have less of a tread pattern than the Innova tyres (supplied with the bike), and the Schwalbes have a reputation for great puncture resistance combined with medium rolling resistance. Not good. Medium.

On went an 8-speed cassette, to replace the 7-speed freewheel. the SRAM PG850 has quite a few cutouts and quite a bit of drilling, so is not as heavy as it looks, and Mermaid's old back wheel with the PG850 gears actually weighed in at 38g LESS than the 7-speed wheel and cassette that came the Hoprider.

Off came the rather heavy Shimano M131 crankset (steel rings, cast cranks), and on went my forged alloy crankset, with an alloy "big ring".

The Shimano M131 48/38/28 is rather heavy ...

Less steel more alloy. Even with a steel middle and inner ring, the Spa Cycles forged set comes in 239g lighter
(rings are 48/34/26, 'cos that;s what I like, and unlike the Shimano unit, the rings are removeable, so you can have pretty much what you want for the ratios.)

The cast ally Shimano M131 weighs in ...
(it is a 170 mm crank)

 ... again lighter (11g), the Spa Cycles forged 175 crank arm I now have on Hoppy.
Longer cranks, but lighter. Hmm.
Forged is better than cast, that's why!

Which crank bolts to use?
I had this (new) pair from Stronglight in my "bits" box ...

... although at only a single gram heavier, the bolts and covers supplied by BTwin are much the same weight.
I fitted the Stronglight ones because they have a "allen" head, while the BTwin ones need a thinwall 14mm socket or a T40 torx bit - yep that surprised me as well - they are 14mm bolts with a torx socket cut into the hex heads of the bolt!
I even swapped the BB for a lightweight aluminium Stronglight item.
Turns out the "original" has a lot of plastic in it, so the BBs weigh about the same, but the new crankset saves about 250g, half-a-pound, even though the old one had 170 cranks and the new one has 175s.
The plastic-cupped BB from BTwin compares favourably for weight with ...

... a Stronglight aluminium-cupped unit.
Oh, and I have 3 water bottle cages, too.
Anyway, in the end, I got Hoppy down to 14.5 kg.

And that is with Marathon Plus tyres (pretty much the heaviest touring tyre available), and heavy duty wheels.
If I splashed out on, say, something as simple as a pair of Campagnolo Khamsin wheels and a pair of Schwalbe One tyres, I could get the weight down to closer to 13kg.
Even simpler, leaving off the luggage rack saves about a kilo too!
So Happy could get down to 12kg or so without breaking the bank.

But as we are, Hoppy is down to about 14.5 kg (a little over 32 lbs)
So that is 3.5 kg (7.7 lbs) less than Mermaid was.

So that is another 3 minutes saved.
I'm going to be carrying less stuff this year. Last year I pretty much took the kitchen sink. Useful if a zombie apocalypse breaks out during the sportive, but not exactly light, or likely to be needed.
So I am hoping to save a 2 or 3 kilos (4.4 to 6.6 lbs) on "stuff".
So that'll be another couple of minutes saved.
Then there is the "aero". My clothes are a lot closer fitting this year, and I have my aero "horns", too. I can get my position lower, and save a bit there, too. Should be good for five to ten minutes off my time.
So what do we have?
6 minutes saved from my weight loss
3.5 minutes saved on the bike weight.
3 minutes saved on tools and "stuff"
5 to 10 minutes on aero.
So 17 to 22 minutes then.
Better keep my head tucked in - 22 minutes is what I was looking for to get my time down to 5 hours.

On the "test run" I actually knocked 40 minutes off my time.
I have done a more thorough analysis of both the saving from better aerodynamics and less weight.

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