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Power on both bikes?

borncrazy

Apr 23, 12 3:05

Post #1 of 15 (1129 views)

Power on both bikes?	Quote \| Reply

Hey guys

For the last few months I’ve been planning on getting a power meter. I was planning to get a Vector since waiting a few months wasn’t going to kill me but have started to reconsider since it has now been delayed indefinitely.

So here’s my current situation.

I have 2 bikes, a 2008 Trek 1.7 and a 2006 Trek 1000 (used as a tri bike, pic in my profile). The drive trains on both bikes have not been modified. (NOTE: One bike is 10-speed, the other is 8-speed) The 1.7 has 172.5mm cranks and 50/34 chain rings, the 1000 has 170mm cranks and 53/39 chain rings (for some reason the trek website says it has a triple). I don’t want to go any longer than 170mm cranks on the 1000, as I am very happy with my position. I’m not too worried about the length of the cranks on the 1.7 and don’t mind changing to a 53/39.

With vector it was simple, without vector it’s seems a little more complicated due to different bottom brackets (I assume, I know nothing about bottom brackets but they look completely different), different crank lengths (not a huge issue though) and different drive trains (can’t use the same wheel on both bikes).

What do you think my best option would be? Bearing in mind, I’m a student so don’t have a lot of money (though I have $1500 set aside for what was going to be a vector) and I live in Australia (don’t know if this changes prices/availability). Or is it impossible without spending a decent amount of money to upgrade the 8-speed drivetrain on the 1000? I already have a Garmin 910xt and do hope to upgrade to an actual tri bike when I get a bit more money.

My Races: Mandurah 70.3 2013 | IMWA 2014

Nicko

Apr 23, 12 3:45

Post #2 of 15 (1098 views)

Re: Power on both bikes? [borncrazy] [In reply to]	Quote \| Reply

If you have bar end shifters on the Trek tri bike, here's my suggestion:

Shopping list:

Powertap Elite+ or Pro (cheapest possible Ant+ hub)
30mm alu rim + spokes
Wheelbuilder Aero Jacket
10spd chain for the Trek.

Wrenching:

Change the tri bike rear shifter from index to friction mode.
Move the 10spd cassette to the Powertap wheel.
Put a 10spd chain on the tri bike.

Now you have one 10spd powermeter wheel for both bikes, that talks to your Garmin 910xt.
The wheel becomes a disc wheel when racing tri's or TTs.

If you buy used you can have everything <$1000 US.

(This post was edited by Nicko on Apr 23, 12 3:48)

tribern

Apr 23, 12 3:56

Post #3 of 15 (1090 views)

Re: Power on both bikes? [borncrazy] [In reply to]	Quote \| Reply

With AUD 1,500 you could get a pretty decent wheel with a PowerTap hub built into it. For less you can get the PowerTap hub laced into your existing wheel.

Cool thing is, when you upgrade your drivetrain, it won't matter what crank and cassette combo you get (unless you switch from Campy to Sram/Shimano) and you can even upgrade your bike(s) and keep the wheel. Looking at the CBD Cycles website http://www.cbdcycles.com.au/...genre=Power%20Meters you have enough options that you could even go here and also spring for an Aerojacket wheel cover http://www.wheelbuilder.com/store/aerodisc.html.

Hmm, as the AUD is so strong, you could even go here http://www.wheelbuilder.com/...owertap-package.html for AUD218 more you can get a wheel set with PowerTap

borncrazy

Apr 23, 12 4:29

Post #4 of 15 (1065 views)

Re: Power on both bikes? [Nicko] [In reply to]	Quote \| Reply

I have 9-speed dura-ace bar end shifters on the tri bike, already using friction mode.

Would I need to change the front/rear derailleur or the chainrings?

Would the 9-speed shifters work with a 10-speed cassette in friction mode?

If i've already got a disk cover and I get the powertap installed on the same rim, would I be able to use the same cover and just make the holes bigger or would I need a completely new cover?

Edit: Added a question

My Races: Mandurah 70.3 2013 | IMWA 2014

(This post was edited by borncrazy on Apr 23, 12 5:23)

jackmott

Apr 23, 12 5:08

Post #5 of 15 (1029 views)

Re: Power on both bikes? [borncrazy] [In reply to]	Quote \| Reply

powertap

upgrade the other bike to 10 speed

tiagra is 10 speed now so it can be cheap

Memorial day sale at ATC and Meet Pro Triathlete Matty Reed - Sat May 25 - Captex!
The newest tri shop in Austin - ATC 360
Freelance sports & outdoors writer Kathryn Hunter

(This post was edited by jackmott on Apr 23, 12 5:09)

borncrazy

Apr 23, 12 5:25

Post #6 of 15 (1013 views)

Re: Power on both bikes? [jackmott] [In reply to]	Quote \| Reply

thanks jackmott, I didn't see your post before I edited my last one. do you think i'd be able to use the same disk cover?

My Races: Mandurah 70.3 2013 | IMWA 2014

jackmott

Apr 23, 12 5:27

Post #7 of 15 (1007 views)

Re: Power on both bikes? [borncrazy] [In reply to]	Quote \| Reply

borncrazy wrote:

thanks jackmott, I didn't see your post before I edited my last one. do you think i'd be able to use the same disk cover?

yeah you could enlarge the inner hole in the disc cover, however its kind of expensive to build the powertap into an existing wheel usually. maybe you could just buy one prebuilt that is the same depth as your current wheel

Memorial day sale at ATC and Meet Pro Triathlete Matty Reed - Sat May 25 - Captex!
The newest tri shop in Austin - ATC 360
Freelance sports & outdoors writer Kathryn Hunter

borncrazy

Apr 23, 12 5:33

Post #8 of 15 (1001 views)

Re: Power on both bikes? [jackmott] [In reply to]	Quote \| Reply

well my friend who works at a bike shop said it would probably be $150+ but he wasn't sure so I'm going to go there tomorrow and ask. Even if it does cost 150 it still looks like I'll be able to get it all for $1000

My Races: Mandurah 70.3 2013 | IMWA 2014

Nicko

Apr 23, 12 8:42

Post #9 of 15 (900 views)

Re: Power on both bikes? [borncrazy] [In reply to]	Quote \| Reply

borncrazy wrote:

Both derailleurs can stay. You only need a 10spd chain to go with the 10spd cassette (which is ultimately dictated by the index shifters on your road bike).
The front chain rings should accept the narrow chain. Test with the stuff you already have before deciding.

I would advice to get a new rim of similar measurements as your existing wheel to go with the PT hub. That way you have two rear wheels that can take your existing wheel cover. It is always nice to have a backup wheel when going to a race (or if the PT needs to be serviced).

It's easy to cut the center hole bigger for the PT hub.

cwg_at_opc

Apr 23, 12 13:52

Post #10 of 15 (813 views)

Re: Power on both bikes? [Nicko] [In reply to]	Quote \| Reply

when i switched my d/a 7400(8-speed) to 10 speed, the new chain got stuck between the chainrings, so
be prepared to buy a new crankset(you might get lucky, but be mentally prepared anyway.)

Nicko wrote:

...
The front chain rings should accept the narrow chain. Test with the stuff you already have before deciding.
...
/quote]

"...I try not to ever ride as slow as 20mph. ;) ... And even more than that, I don't race with a speedometer. My computer is set up to show Power // Cadence // Time. I don't actually ever know how fast I'm going. I only know that if I'm in 53/11, and it takes more than 100rpm to hit my target watts, it's time to coast." - Jordan Rapp on '09 IMC

JollyRogers

Apr 23, 12 17:45

Post #11 of 15 (741 views)

Re: Power on both bikes? [tribern] [In reply to]	Quote \| Reply

tribern wrote:

Cool thing is, when you upgrade your drivetrain, it won't matter what crank and cassette combo you get (unless you switch from Campy to Sram/Shimano) and you can even upgrade your bike(s) and keep the wheel.

Even if the OP switched to Campy there are two options available with the ANT+ hubs: a shimano-splined, campy spaced cassette sold by Saris or a Campy freehub which requires no tools to swap. You could even leave a cassette on each freehub and do a no-tool swap if the bikes were equipped differently.

number114

Apr 23, 12 18:35

Post #12 of 15 (713 views)

Re: Power on both bikes? [borncrazy] [In reply to]	Quote \| Reply

Not sure if you already have a computer or watch to collect the ANT+ power data, but don't forget to add that to your overall cost.

borncrazy

Apr 23, 12 19:22

Post #13 of 15 (682 views)

Re: Power on both bikes? [number114] [In reply to]	Quote \| Reply

Already have a 910xt so all good on that front.

My Races: Mandurah 70.3 2013 | IMWA 2014

NickW

Apr 24, 12 3:47

Post #14 of 15 (599 views)

Re: Power on both bikes? [borncrazy] [In reply to]	Quote \| Reply

Is there a reason you can't simply change the cassette when you move the wheel from one bike to the other? It takes about 2 minutes tops.

borncrazy

Apr 24, 12 4:32

Post #15 of 15 (580 views)

Re: Power on both bikes? [NickW] [In reply to]	Quote \| Reply

I could do that, though I'm prepared to pay $100 to change to 10-speed so unless the chain gets caught between the chainrings, I'd rather not have to change the cassette.

My Races: Mandurah 70.3 2013 | IMWA 2014