Technical FAQ: Powertap rim choices and disc-brake cleaning
I currently have a Cycleops Pro Powertap rear road wheel (rim brake). It is a 32-spoke hub laced to a Cycleops rim, which I think might be a rebranded Velocity aluminum rim. I have the matching front wheel but wanted to re-build them into a nicer carbon-rimmed wheelset, keeping the Powertap hubs. Most of the carbon rims I’ve looked at have fewer drilled holes, like 18, 20, 24 count. Do you know of any 32-hole carbon rims? I don’t really race or TT, so I don’t need anything with a deep profile, and I am less concerned about weight.
Secondly, assuming I find a compatible carbon rim, can I use a bladed spoke like Sapim spokes? I think I’ve heard you can only use regular spokes laced in a certain pattern for the Powertap hubs. I was wondering if you happened to know this as true?
Here is the response from Rich Sawiris, owner and founder of Wheelbuilder.com, expert on wheels and making them with Powertap hubs.
“There are no great options for 32H carbon road rims, however it is possible to swap the hub shell on the Powertap Pro for a different hole-count. We still have a few Pro model shells around the shop that would allow the transfer of an existing torque tube for a lower spoke count. A 24H count would give you the greatest number of carbon rim options from every major manufacturer.
Bladed spokes are fully compatible with a PowerTap hub if the major dimension of the blade does not exceed 2.6mm. The most popular options are the DT Aerolite, Sapim CX-Ray, and DT AeroComp models. The PowerTap hub requires a minimum 2-cross lacing pattern on the non-drive side flange, but we recommend it on both flanges. Typically, we would lace a 24H hub with 2X lacing and a 28H or 32H hub with 3X lacing.”
Can you provide advice on cleaning road bikes with disc brakes — techniques, cleaner, etc.? The way that I clean my bike seems to be associated with having grease or grime on my front pads (and in turn producing loud squealing and reduced braking power) a few rides after my cleaning. My LBS is guessing that my use of dish soap and water to clean the frame may be the source of the problem. More generally, with the growth of disc brakes on road bikes, there might be great interest among VeloNews readers in an article on proper cleaning of road bikes with disc brakes. At least it would be of interest to this reader.
Here are answers from a number of disc-brake product managers.
From FSA’s Joel Richardson (formerly with Hayes):
“The safest route when cleaning the bike would be to remove the front and rear wheels, remove the brake pads and install the bleed spacers that come with the brakes. This will ensure that the pads and rotors are not contaminated during the cleaning. The bleed spacer will prevent the caliper pistons from getting pumped out if the brake lever is bumped while cleaning.
“Now this is a bit of a process and inconvenient if the user cleans their bike after every ride. Most disc-brake manufacturers recommend isopropyl alcohol to clean the rotors and disc-brake components. However, mild dish soap and warm water is also acceptable. With this in mind, I suspect that the soap and water is not the root cause of the noise for your reader. Instead, the grease and road grim that the soap and water are washing off the bike and drivetrain may be making their way on to the rotors and/or brake pads. If this is the case, then the pads will need to be replaced and the rotor cleaned per above.
“Another possible cause for the noise and loss of power relates to burnish. The brake pad material is transferred to the surface of the rotor and this in turn creates the friction needed to stop the bike. It is possible to remove some of this material when cleaning with soap and a brush. On the next ride the pads will make noise and power would be low until the burnish process has been completed again. If the power has not returned and the noise continues after 15-20 good stops from 10mph then the pads may be contaminated.
“Basically, we’ve been cleaning disc brake-equipped mountain bikes since 1998 with soap and water and have never seen an issue related to the soap.
“One final possibly is related to drivetrain maintenance. Mountain bikers have learned that you must be cautious when cleaning and lubricating your chain and derailleurs. Overspray from cleaners or spray lubes can easily pass through the spokes on to the rear rotor. The next time the brake is applied, these contaminants are transferred to the brake pads, and it’s time for new pads.
“Hope this helps you with your column. As mountain bikers, we are accustomed to the nuances of disc brakes. With the introduction of road disc brakes we have a new group of riders that may not be aware of all the tips we’ve picked up of the last 17 years.”
From Eric Schutt, media manager for Hayes:
“When washing a bicycle with disc brakes, we suggest using isopropyl alcohol to clean the rotors. It’s best to avoid any detergents, chemicals, or lubricants from coming in contact with disc brake rotors and pads. If you wanted to go the extra step, you can use a clean, lint-free towel to clean the pads. You can either run a towel thru the brake slot in the caliper, or remove the pads to clean them.”
From Stefan Pahl, product manager at Magura:
“We haven’t got experience with road disc brakes, but with MTB disc brakes, and they should be identical.
“We recommend cleaning rotors with soapy water and a clean brush. But you can also use disc cleaner sprays or alcohol. Make sure to always use clean rags or towels!
“Be careful when using brushes or sponges when cleaning with soapy water, which are not clean and might have some grease or oil residue from the drivetrain. This can contaminate the rotors/pads.
“Contaminated pads, especially with organic compounds, have to be replaced. The oil or grease is soaked up by the pad material like a sponge, the pad will never perform equal after cleaning.
“Other advice: Be careful when lubing the chain when using sprays. Never let oil mist get onto the rotor.”
“Some bike cleaner sprays contain oil or other lubricants to make the bike shine and repel water. They will also contaminate the rotors and pads.”
From Bryce Olson, customer service representative at TRP:
“Cleaning and washing a road bike with disc brakes definitely presents some issues when it comes to keeping the pads and rotors free of contaminants. Hands down, the best way to avoid squealing pads as much as possible is to remove the pads before washing the bike. Granted, this takes a few extra steps and a little more time, but is the best way to avoid the issue. Any pad that gets wet, whether it’s contaminated or not, is more likely to squeal than a dry pad for a while until they dry out. While we haven’t done any scientific or dedicated testing, in our experience using a bike-specific wash instead of dish soap tends to cause less noise issues. Finally, cleaning the rotors separately, after washing the bike, with isopropyl alcohol to remove any residue or contaminants before using the pads is highly recommended to help keep the pads clean and contaminant-free.”