Dear Lennard,
I am refitting the components on my son’s bike, and was looking for150mm crank arms. Where did you find them? Are they single, double or triples?--Ron

Dear Ron,
HSC makes 150mm in double or triple. www.hscycle.comTA used to make that length as well, but I have not seen any in years.--Lennard

Dropping the chain
Dear Lennard,
My chain continues to jump past my small chain ring when I go fromthe big ring 53 to the small 39 tooth. This always seems to happen at themost inopportune times. I have the front derailleur adjusted to where itis all but touching the chain in the 39X25 combo. I’m running an all Ultegracomponents on a C’dale Caad 5 road bike. Let me know if you have any suggestions.--Neil

Dear Neil,
Try a Third Eye chain watcher or a Deda Dog Fang. These little plasticgizmos clamp around the seat tube, and you set the height and rotationso that it pushes the chain back onto the inner ring whenever it triesto climb off. Either one is a no-brainer to use and completely effective.--Lennard

Can I switch?
Dear Lennard,
I have a Litespeed Vortex with integrated headset. The current headsetis made my Cane Creek I would like to change to Campy but, someone toldme that once I have Cane Creek that is all that I will be allowed to replaceit with. Is there any truth to that? And if I can replace with Campy, isthis a job that someone with average mechanical skills and knowledge cantake on?  --Glen

Answer from Litespeed:

When we decided to utilize integrated headsets on our bikes,we initially wanted to accommodate the Cane Creek and Campagnolo designs.However we discovered that the differences between the two designs arelarge enough to warrant deciding on one of them to guarantee a perfectfit. While we certainly appreciate Campagnolo's reputation and quality,we decided to go with Cane Creek to allow for a wider range of spec options.Which means that all current bikes will only accept the Cane Creek integratedheadset. A Campagnolo Hiddenset would require slightly larger integratedcups and thus this could not be facilitated at the local bike shop.
Herbert Krabel
Litespeed

Dear Lennard,

Dialed in or worn out?
Hi Lennard;
I've noticed that whenever I see pictures of pro racers warming upfor time trials, they never have the disc rear wheel on their bike, whyis this? Is having absolutely fresh rubber more important than having perfectlydialed shifting? Or is the sound of a disc on the trainer really that bad?--Rob

Answers from some professional riders:

I can't speak for everyone, but I don’t use a disc if I amwarming up on the trainer because when you do an effort, sometimes evenif everything is adjusted correctly, trainers tend to shred tires. So Ido it to avoid torching my tire on my race wheel in case anything goeswrong.

Also some skewers work better in a trainer than others, so it may bethat a training wheel skewer fits into the little trainer grippies better.
Colby Pearce

It’s just to keep wear off of the really light, skinny tires so themechanics don't have to replace the TT tires every third race.
Jonathan Vaughters

Going disco?
Dear Lennard,
As a shadetree bike mechanic who is working on a friend's bike, I havea question. Are there any disc brake adapters available for forks to converta V-brake fork to a disc brake fork? My friend had to crash replace theframe, and they sent a disc specific frame back to him. He has found aset of Avid's and a set of Deore/Sun Rims wheels for me to install, butthat will leave him with a Disc rear and a V front. I wouldn't think itwould pose a problem, but just wanted to check to see if there was an inexpensiveadapter made. --Brandon

Dear Brandon,
Not that I know of, and I doubt you would want to trust them if therewere. The geometry, size and shape of dropouts and lower legs varies somuch on forks that a universal adapter would fit badly on all but the onefork for which it was designed. Furthermore, slippage would always be anissue. --Lennard

The consequence of a bad weather ride
Dear Lennard:
I'd like to know what you recommend for smoothing chewed up rims. Aftera few bad weather rides, I've been unable to silence my brakes. AlthoughI cleaned the bike after each ride, I was unaware of the teeny-bits-of-debris-embedded-in-the-brake-padsproblem for long enough that my rims have suffered some scratches. I'vetried cleaning them with soap and water, cleaning them with rubbing alcohol,and cleaning them with 0000 steel wool. Finally, I realized what was wrong,and sanded my brake pads down to a clean surface. I'd like to really getthe rims smooth before riding on my newly cleaned up pads, but the steelwool is taking forever, and 290 grit sandpaper, (tried on an old wheelI had lying around the house), seems a little too aggressive. Should Igo for it with the 290? Or order a bale of the 0000 steel wool and cancelmy appointments for the next two weeks? Or is there a better way? --Rob

Answer from Mavic:

What's happened to the rim is not unheard of with a machinedsidewall. If you could look at a cross section with a magnifying glassit would appear as peaks and valleys. Something has caused the peaks toerode. In this case it may have been some grit picked up from the wet roadsacting like a type of sandpaper, but old and/or hard brake pads could bethe cause too. This sloughing process will continue on it's own scheduleuntil the high points have been surfaced so you can speed the process byusing the steel wool approach or the fine grit sand paper. We make a gummystone used for cleaning ceramic sidewalls that works pretty well here.It may not hurt to change the pads for something newer/softer but the metalbits will continue to show up until rough edges are gone. Keep checkingand cleaning the pads.
Hope this helps
Bill Douglas
Mavic USA

How much grease?
Dear Lennard,
I have no experience with working on bikes, so I purchased a copy ofyour mountain bike book and have been slowly making my way around my bikeas a winter project. As I was working on overhauling my wheel hubs I wonderedhow much or little grease I should use in the ball bearing area. --Michael

Dear Michael,
A thin film is plenty. But over-greasing is rarely an issue, either,unless you get it in the center of the hub around the axle, where shearingthe grease as the hub turns would cause friction. --Lennard

Follow-up on adjusting tight Ksyrium hubs:
Dear Lennard;
I have a pair of Ksyriums that had a similar problem. I put the wheelin a truing stand and adjusted them back and forth with the pin-tool. thewheel was sticky even when the cup was almost falling out.
It turns out that one of the drive-side cartridge bearings was shot.Who knows why? It just was. Went to my local shop, they pulled it out andput a new one in and voila!

Now I just wish I would have done this BEFORE the time-trial. --Geoff

Follow-up on cleaning ceramic rims:
Hey Lennard,
 As a follow up to the ceramic brake surface question...I re-adjustedmy brakes to meet my preferences, replaced the pads, rode the bike fora break-in period and the brake system is now performing wonderfully.

 Thanks for answering my questions, forwarding them on to Keith.--Mike

Dear Lennard;
realized something in my delirium while climbing a long hill tonight– Mr. Bontrager is right. My braking is getting better and better as therims get older. I started with ceramic specific pads when the rims werenew, but they didn’t have enough power, so I switched to the sticky Kool-Stopblack pads. But as the breaking surface gets smoother and better, I’m clearlymoving towards harder and harder pads. This year it’s Severe Weather Salmoncolored pads, so maybe next year it will be set of Green KS ceramic pads.If things continue at this rate, I may have to put on Brillo pads in afew years. --Steve

---

VeloNews technical writer Lennard Zinn is a frame builder, a former U.S. national team rider and author of several books on bikes and bike maintenance including the pair of successful maintenance guides " Zinn & the Art of Mountain Bike Maintenance" and "Zinn & the Art of Road Bike Maintenance." Zinn's VeloNews.com column is devoted to addressing readers' technical questions about bikes, their care and feeding and how we as riders can use them as comfortably and efficiently as possible. Readers can send brief technical questions directly to Zinn. Zinn’s column appears each Tuesday here on InsideTri.com.