Time Trial / Time Trialling / TT

And bigger cogs = more efficient?

bigger cogs = more efficient?

In general, yes, but you weirdos with your dérailleur mechanisms also have to consider chain line, since straight chain is more efficient than bent. Given the alignment of normal road drivetrains, the 62 is probably going to be win both ways, as you're likely to spend more time with the chain straighter.

Basically what Gbj said but with graphs and stuff. I knew I'd seen this video before just didn't realise how old it was
https://www.bikeradar.com/features/friction-facts-free-speed-from-proper-shifting/

Found this on water bottle drag there is one real world aero penalty that wasn't possible to account for between the two BTA's tested because with a regular bottle Bta you have to sit up to drink but it gives you a pretty good idea. My bike set up like this but with acetate sheet fairings attached to form a nose cone broke even in proper aero testing compared to the bare frame. Also I'll try and find some proper data but there seems to be a trend for pro riders who wear very stubby or no tailed aero helmets like your air attack and their riding position. They all have a similar relaxed neck low head eyes down and lowish hand positions and i remember testing well with a Bambino in a similar position in my first ever aero testing session despite the kask supposedly not being very aero in stand alone testing. Obviously everything aero is rider specific and I'm just making assumptions but if your definitely going with the air attack and you said your upping your front end a higher elbow lower head position could work well for you. Hope some of that helps.
https://www.aero-coach.co.uk/water-bottle-testing

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Events are up!

Breckland 12hr, Aug 7th. Unlikely if I try and ride the twentyfour12 MTB thing the week before.

Well, that was quick. Flatmate just taken delivery of this, got it under £300, and its looking OK. Paired with my tubular Zipp 404 front thats under 1550g for the set. A modern 60-80 combo would probably be just as, if not more aero, but thats also cost about the price of the whole TT bike, sooo...

Also on the way the profile designs bottle for between the extensions. This, and some more about home-made di2 TT shifters in here.

Any interest in a viewspeed Ti front skewer? Super clean front end, infinte watt saving, blah blah blah. Not my pic:

Anyone know an affordable option for clamp-on TT brake levers that still leave space for a bar end lever? The Jtek levers below are £40 each from SJS.

Why do you want to brake while using the extensions?

If you want to slow down, you sit up and if you want to slow down more you grab the brakes on the basebar.

If you want to slow down, you reduce pedalling torque and if you want to slow down more you invert the sign thereof

fixed tfy 🙂

Brake levers must be secured to the handlebars in such a position as to enable the competitor to readily apply both brakes whilst holding the handlebars at their widest point. The width of handlebars shall be no less than 35 cm

You can do that with gears, it's just WAAAAAAY slower. :P

As I'm sure you know, some courses also have specific rules about not riding the RABs/turns on the extensions.

I know some/all of the A31 courses apply this like H50/8 type rides.

Why do you need more than one brake lever?

*fixed*tfy

Insert "page refresh fail" comment here.

Sorry I should have been more specific.

I will have no extensions. Only the bullhorns. It's not going to be a proper TT bike, just a fun build.

Scout ebay for some 'vintage' stuff?

https://www.ebay.co.uk/itm/185248592416?hash=item2b21ad3220:g:ZUsAAOSwwTph2rr4

Anyone on here have a Notio and utilise regularly? Few things to pick brains about..

no extensions. Only the bullhorns

Depending on which bullhorn, you'll probably be looking for 23.8mm clamps, not the 22.2mm clamps found on most flat-bar levers and those JTek "aero-or-die" levers

That is a sound point. Likely to be 23.8 or 24.0 mm. I'll wait until I get my bullhorns and then go from there.

Those have no room in the end for a bar end shifter. But yeah it'll likely be eBay to the rescue, in any case.

Yeah, I got bored looking.

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Use any lever thats larger than your bullhorn's diameter, and then a shim/spacer.
If you send dimensions I'll make one for you. See on my "going out to drink aperol spritz in London Fields" bike:

Drop me a message if you need one made. If you'll be using 31.8mm oversized ones, I could make it eccentric so it has space to guide the cable of the shifter too.