Swapping out a powertap...not so simple?

Joseph Lombardi

Not sure if this belongs here but seems well enough to ask......

I have a powertap on wheel from wheelbuilder on my TriBike....

I have a roadbike...no powertap....and I want to ride on my roadbike with power....

Normally; I understand...just swap the wheels...right...no problemo....

Except...my road bike has a compact cassette, only 9 rings/gears (18) and my tri has more...so I can't just swap it as the front derraileur isn't matched etc...

Can I put swap the cassettes ...putting the compact cassette on the hub with the powertap...without any consequence?

Joe Matchette

Yep. (assuming they are both the same, e.g. Shimano)

I do it all the time with my bikes. Tri bike is 10-speed cassette. Road bike is (ancient) 9-speed.

tgarson

Joseph,

First real quick, the reason why it's not so simple to swap the wheels is not because one bike is a compact and the other is not. Being a 'compact' only refers to the number of teeth on the crank (and the bolt pattern of the crank), but has nothing really to do with the rear derailleur or your rear cassette.



The cassette is different on your road bike than your tri bike because your road bike has a 9-speed rear derailleur (from the sounds of it), while your tri bike is a newer 10-speed.



Those semantics out of the way, I believe the answer is yes. As long as your rear hub is not a dura ace, which it is most likely not, I'm pretty sure most 10-speed Shimano hubs will accept a 9-speed cassette. So you should be able to swap the cassettes using a chain whip and a cassette lockring tool and ride the 9-speed cassette on your PT wheel.



But, I'm a Quarq guy so someone will have to fact check me there in case there is some PT magic I don't know about when it comes to swapping cassettes.

[Deleted User]

I was able to switch out mine compact to a triple- change out cassette and wheel. Did it a few times..then went on EBAY and just bought another used PT wheel. $500....couldn't pull the trigger on a Quarq since already invested in a PT. Gives you a chance to clean your cassette while your at it.

Tom Glynn

I will probably work, but with different cassettes, 9 vs 10 speed, and compact vs regular cranks, sometimes chain length may be an issue, so for example if one bike is an 11-21 with a regular cassette and one an 11-28 compact crank, set up for the different bikes, then the 11-28 may have a slightly longer chain and my cause issues when swapping out.

I have my road and tri on the same setup - compact cranks and swap out the rear wheel with the same cassette, typically the 11-28.

Jeff Sullivan

yes in theory it can be done - i switch my PT wheel between my Shimano (tri) to my Campy (road) - the shimano is 10 speed & campy is 11 speed - i have to switch hub assy's first and add a small spacer - go to your LBS to get the hub assy (if needed) & spacer (probably req'd) - they will (should) know the dimensional differences between your 2 systems - my complete system was about $100 - switch over about 10 min

John Withrow

The other little tweak you might need to do is to adjust your Rear Deraileur on your Road bike each time you swap the wheel to your PT wheel. I know the hub on my PT wheel is ever so slightly wider than the hub on my non-PT hub. Even 5mm difference will require a quick adjustment to the RD. Once you do it a few times, it's no big deal.

Steve West

My roadie has a triple up front and 9 in the back. Tri bike is a compact with 10 in the back.

I bought a second cassette hub from WheelBuilder ($70 I think) just so I could have both available for spring conditions (crappy roads, bad weather) where I can do the tri bike on the trainer but use the roadie outside on frost heaves, sand and grit. It's a really cool system cause the hub and cassette just pop off - no tools.

Come regular warm season I can use the 2 hubs for different cassettes (12-25, 11-28) on the tri bike and swap in seconds.

Dave Campbell

I did the same as Steve, bought an extra freehub and leave a 9 speed cassette on one and a 10 speed on the other. Takes 2 minutes to move the wheel from my 9 speed road bike to my 10 speed tri bike. Assuming you have a fairly new Powertap hub. Be careful and do not loose the spacer behind the freehub!

robin sarner

Good answers.

But the reason why all our bikes are now 10 speeds. No swapping issues.