Tester's T3

Yes, but what length of outer? Still needs maths to work that out.

Hey Tester, I've got a Cervelo T1 which uses the same forks as your T3. How did you drill the fork to fit your brake?

Not the same fork at all, the T3 came with the FK26, the T1 comes with an FK24, see http://www.cervelo.com/en/engineering/ask-the-engineers/the-p4-fork-a-prodigious-father.html for the difference.

Sorry, I thought it had the FK24 too. Did you already had a brake hole then?

Yes, because the FK26 is made for the P2/P3 Tri/TT bikes.

That's a shitter for me, I was hoping you might have some answers. I've seen a few T1's with a brake fitted, but I'm unsure of the drilling procedure or if it's even recommended on the FK24. I looked at some of the clamp on brackets but none will fit the blades of the fork.

Sell the FK24 and buy an FK26?

Sell the FK24 and buy an FK26?

Nah, wouldn't want to sell the 24's. Buying the 26's might be an option so I can swap back to brakeless. Is there any clearance issues with the track nuts in the drop outs?

The FK26 has full carbon dropouts, I'd avoid track nuts as there's a temptation to overdo the tightening torques and damage them. Better to use an Allen key skewer if you have a hollow axle to fit your hub, or follow my lead and make new bolt-on axles.

Has this been resolved yet?

It has now

2 Attachments

Do they slow you down?

Will find out when I ride it, it was OK with the too short length of Nokon, I'm hoping for a slight improvement from this flexi-noodle.

Did it stop you?

Well, I didn't run into anything. Jumping off my MTB (8" rotor, 4-piston hydraulic caliper) onto the T3, it's pretty obvious which one has the better brakes :-)

@8bits

160mm is midway between 140mm and 177.5mm (on a geometric progression)

For a given gain ratio, 140mm and 177.5mm give approximately identical performance

The relationship between crank length and performance could be one of these three things:

1. A straight line
   
2. A humped curve
   
3. A dipped curve
   
   

If it is 1, 160mm will be exactly as good as 140 or 177.5
If it is 2, 160mm should be better than either 140 or 177.5
If it is 3, I've made a terrible mistake, but that should be reasonably obvious once I've tried the 160s on my RollerFort. It's also by far the least likely.

In theory, then, by switching down to 160s, I get either a gain in power or nothing. I stay close enough to the 165/170 cranks on the rest of the fleet to be comfortable jumping from bike to bike. I get 17.5mm of wiggle room on my position to mess around with saddle height and bar drop without bumping into hip closure angle limit. There might be aero gains to be had.

I get either a gain in power or nothing.

But how will you know? ;)

But how will you know? ;)

I'll go faster :-)

In answer to your other question, it will depend a bit on how things go on the rollers with the short cranks, but initially I think 58/17×160 gets me roughly the same gain ratio (7.058) as 53/14×177.5 (7.060)

That's an option if things go very well, experience suggests that 58/13 won't be required until I'm threatening Dowsett's 10 record (99rpm = 17:16)

that's interesting, never read an explanation like that, my thought would be that a larger crank arm would yield more leverage and less force would be applied for a bigger gear (TT)

@Ordinata

Plenty of room for a 58T, the T3 stays are bowed inwards for clearance, I use a ~46mm chainline, and 58T is only 10mm larger radius than the 53T that's currently on there.

my thought would be that a larger crank arm would yield more leverage and less force would be applied for a bigger gear

That's correct. In conventional terms, I'm switching from 100" gear with the long cranks to 90" with the short cranks. The pedal force and foot speed remain constant, but the foot goes a shorter distance per revolution, and the cadence goes up as a consequence.

What cranks to replace the Zipps?

That's not definitely fixed yet, but candidates are:

1. Rotor 3D+MAS - definitely comes in 160mm, fits my existing BB386 cups
   
2. Vision Metron - probably comes in 160mm although the short ones have yet to be seen in the wild, also fits my existing BB386 cups
   
3. Find a way to fit a chainring to 160mm ISIS Unicycle cranks, probably with some kind of adapter like Cliff Voller's from Fibrelyte
   
4. Win lottery and persuade Zipp to make 160mm Vuma Chrono Pista with a shorter axle to go with custom frame & wheels built for 30mm chainline and 80mm OLN, bringing the Q down to <120mm as recommended by @xavierdisley http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0838.2012.01479.x/abstract
   

New lock ring!

1 Attachment