Time Trial / Time Trialling / TT

So my hillclimb results from last year are valid?

Should be, if HC follows the pattern of other championships.

A mechanical, rather than racing, question but this seems the best thread to attract the attention of those in the know.

I put my friend on 1x10 over the Winter (55t Fibre-Lyte, 12-25 DA, DA RD, Connex 10SX, mechanical shifting) and it's been faultless until recently: raced twice a week over bumpy evening 10 and variable opens up to and including 50).

1) On a downhill section she slammed it 3/4 sprockets down the cassette to top and it dropped off the inside of the ring.

2) Immediately prior to a downhill section, she changed from 9th to 10th and hit a bump: the chain dropped off the outside.

There is no measurable wear to the chain.

My guess is that in the first case, the large change in gear caused the RD to "bounce" causing the chain to ripple and in the second, the bump in the road had the same effect.

However, the fact that on the same courses this hasn't been a problem until now makes me suspicious.

In the short-term I've taken a link-pair out (and she reports that the shifting is crisper as a result; the 25t sprocket isn't used) and today's 10 was incident free.

I've got a bit of a sweat on, as she's off to Mexico in September for the "world" sleeveless champs.

TIA

Chainguide of some sort?

Aero plz.

More seriously, it's been fine all year until now which suggests there is a "problem".

The only thing I can think of, is that the chain has developed lateral play,

Having said that, the bottom sprocket isn't used at all (as I haven't sorted the RALTech) and only the top six get any real use.

Cheap track disc

Yeah I saw that - Good price for a little wobble.

I need to sell my Hed Track disc actually... @ewanmac Fancy it instead of faffing about with the Zipp conversion?

Probably not, sorry. having a dedicated disc for a very small number of races seems silly and I think MagicMan (from TTF) has one of the conversion kits. If the axle falls through I may change my mind but I think I'm sorted for now.

Last minute decisions...So, 10mi TT with ~200m of elevation. Not a particularly powerful cyclist, but better uphill than most. For for the rear wheel do I go:
G3 Powertap hub, 32h Open Pro & Raltech cover ~1300g
or
50mm Carbon clincher ~900g

Powertap

Presumably this is for nat 10?

A few people are beginning to say the rear doesn't actually make much difference between a deep and a disc but flo shared some data indicating that the weight penalty has to be huge to make it trump aero.

The ther thing you need to consider is how much difference there will be when going down the hill, as only half the course is up!

Yeah, only half the course is uphill, but I'll be spending longer durations on the uphill sections than downhill, hence why I'll be conserving power when descending and applying more of it when ascending.

I would like some post-ride data though, so might go with the heavier PT wheel...

Rule of thumb is 1kg lost over 100m height gain is worth 2s right? So you've got a potential 2s gain on the uphill section... Having the power data could save you more (pacing)?

Cool, that's it decided then. My hill training for the past month has involved full panniers on an old steel frame anyway, so whatever I ride will feel like I'm flying...

hmmm.
Sunday weather looks terrible, but whatever- at least it appears to be a cross wind.
Be fun to test everything out.
Anyone else on CC London 25?

Also gonna attempt some hillclimbs after September I think.
Weight loss probably needed (though I am sub 65kg at the moment(maybe not after today's cheat day)).

After September? That's midseason! And lol @ needing to lose weight at sub-65.

lol @ needing to lose weight at sub-65

Maybe he's only 1.5m tall

Timing won't allow much else....
There's just a little more belly to go- but food is just too enjoyable.

(177cm for MDCC's sake).

Fixed wheel TTers - when comparing your gearing for 25s and 10s, by how many gear inches (if any) do you typically drop down for the longer distance? Ta.

by how many gear inches (if any) do you typically drop down for the longer distance?

Not at all. You should be riding 25s at almost exactly the same speed as 10s. In fact, you don't need to gear down for 50s either, you'll be going slightly slower (unless you're really good), but you'll also want to drop cadence a bit for the longer duration. Going 1mph slower, which is normal for mortals when going from 25 to 50, will drop your cadence by about 5rpm for typical speeds and gears, which is probably about right.

Anyone want some white giro empire in 46. Worn for 20miles.
Prefer my 45.5

I dropped chains too often with 1x11. I use a mechanical FD for now. If someone knows of an aero chain guide, please let me know.

I seem to have entered the UTag 10 on P881R.

Given I've just raced across Europe, should I bother trying to beat 19:55 on it? Anyone know the course?

18:39 CR. Think you could manage a PB, depends what your power is like after TCR + conditions.

Depends whether you entered the TT or road bikes event...