Editor’s Note: VeloNews tech editor Nick Legan is a former ProTour mechanic who most recently wrenched for Team RadioShack at the 2010 Tour de France and elsewhere. His column appears here every Thursday. You can submit questions to Nick at email@example.com, and be sure to check out Nick’s previous columns.
I have tried on several occasions to find the Q-factor for road cranks from various manufacturers without success. Information on Q-factor for the major road crank manufacturers would be appreciated.
— Tim Gavin
I recently spoke with Alex Wassmann, SRAM’s On the Road guru, about Q-factors. Here is what he had collected for Lance when he switched from Shimano to SRAM. Lance is very particular about Q-factor and uses spacers on his LOOK Keo Blade pedals to get his required stance or width.
Shimano DA 7900 – 147 mm
Campagnolo Ultra-Torque – 145.5 mm (labeled on the arms)
SRAM BB30 – 145 mm
SRAM GXP – 145.3 mm
SRAM SRM/Quark – 145 mm
none of these measurements use pedal washers included with some cranks. Pedal washers are included to protect carbon crankarms from CPSC flat pedals (the pedal wrench flats will dig in and can ruin the arm).
(Related: Some Lennard Zinn columns about Q-factor)
I’m in my mid-fifties, and going on a long bike ride, from Venice, Italy, up over the Alps to Munich, Germany. Our highest elevation will be an 8,000-foot pass. My question is, to help on the climbs, I’d like lighter wheels, which would be tubulars. But since it will take me 5 to 6 days to do this ride, and I’m far from home, I’m thinking of sticking with clinchers, which would be easier to repair if I flat.
— Michael Olexo
I have to start by saying that I’m quite envious on your upcoming ride! Sounds like an epic in the making. While I’ve had the chance to see many beautiful places like the Alps, I’ve yet to ride most of them.
In thinking about your scenario, I’m gonna have to say that you should stick with clinchers for this ride. There are a couple reasons, one of them involves the mountains you’re about to tackle, or more specifically descending them, and the other is a perspective on the weight of your bike.
While I don’t find roadside tubular tire changes any more difficult than a clincher, the clincher is more secure once repaired. The tubular wheel would need at least one layer of glue and many hours to dry enough to make it safe for extended descending. I don’t think you’ll want to end a good day in the saddle so that you’ll feel secure descending on a recently installed tubular. Clincher tires would keep you rolling more consistently in the event of a puncture.
When thinking of overall bike weight you also need to consider the weight of carrying a third (spare) tubular tire. I would prefer to carry two clincher inner tubes and, for a similar weight, be able to repair two punctures. I might have a slightly heavier bike, but I’ll be able to keep rolling and importantly, enjoying my ride!
Of course, if you will have a follow car, then going with tubular wheels and having a spare set of wheels behind you would work well too. You can then have your faithful follower peel the punctured tire, throw on some glue and your wheel is ready for the next day.
I would also recommend that you ride aluminum rim whatever wheels you decide on. Carbon rims and pads have come a long way, but if conditions turn nasty carbon rims can eat a set of brake pads. Aluminum still offers superior braking.
I would also recommend that you honestly examine the gearing you have on your bike. If your gearing just gets the job at home, it might be a bit too ambitious for a week-long adventure. I would recommend a compact and a 28-tooth cassette, if not a triple. Fatigue is inevitable, but misery isn’t. Best of luck and be safe out there!
Before gluing my first set of tubular tires on a new set of carbon rims, I did a lot of reading to ensure I prepared the new rims and tires in the best way possible. These tires have successfully been in place for about 18 months now without incident.
I’m now wondering how long before I should consider re-gluing? Now in hindsight, I did a poor job of stretching the rear tire evenly when mounting to the glued rim which resulted in an elongated tire opposite the valve stem (i.e not quite a perfect circle). I’d like to remove and re-glue the rear to remove the bumps I feel when at speed. Are there any special considerations or rim/tire preparations needed when removing and re-gluing a used tubular tire on a used carbon rim? Any tricks to get even tire stretch when applying the tire to the glued rim to avoid the elongation I’ve experienced?
You’re in luck. It’s not hard to check whether or not your tires need to be re-glued. Deflate them and try to peel them off by hand, checking around the entire circumference of the rim. If you see dry, cracked glue and the tire begins to come off easily, then you’re due for some glue. If the tire stays firmly in place, you’re good to race! (I should copyright that!)
That said, if you’re not happy with the rear tire’s hop, then by all means, put it off and have another go. If you’ve never taken off a tubular you intend to use again, know that you need to be very careful not to tear the base tape. Some tires like to delaminate when taken off.
I would recommend a fresh layer of glue on the tire once it’s off. Let that dry overnight. The good news is that your previously glued tire has stretched for the past 18 months and it will go back on quite easily. In fact you’ll need to be careful to not overstretch it when you stick the tire.
On the carbon rim, don’t get too carried away. If you have a nice even layer of glue that stayed in place, that’s a good thing. Don’t mess with it. With a truing stand and a utility knife I typically spin the wheel and scrape the edges of the rim to smooth the glue a bit. Some mechanics buy narrow wire brushes to even and roughen the glue surface.
When your tire is dry, make sure to wipe the rim with a clean rag before you apply glue. Don’t use any solvents, but get as much debris or loose glue off as possible. These things only inhibit a good bond.
In the future, I would recommend stretching your tires a bit longer. Then glue your tire and your layers on the rim and let them dry. Before you put on the last wet layer of glue, practice installing the tire to get it on evenly. If you have the time, you can even stretch the tire again once it is pre-glued (sometimes they tighten up again). Just make sure that it’s on a dry rim.
There are lots of little tricks to tubular tires. Only experience though makes it easy. Good luck Dan.
I’m just curious, if a pro crashes and say he marked his frame, scratched his shoe, or cut the saddle just a little, do they switch completely to a new one or keep on using them? I remember you mentioned some pros find a fond attachment to a component such as their saddle of preference, so if that gets damaged a little do they get a new one or keep their old one?
— Tony Yang
Shoes get scratched and saddles get scuffed. Unless there is either a functional/structural reason or a glaring aesthetic reason, there is no need to change them. Saddles do break in and to put on a new one mid-race can spell doom for a finicky rider.
Every pro comes to a race with two pair of shoes. One he/she will race on and the other will go in the team car in his/her rain bag (a small personal bag with a rain cape, gloves, vests, hats, etc.). In even small crashes I’ve had riders break a cleat or a buckle on their shoes. They can change and continue on.
On the other hand, if a frame gets “marked” as you say, that always warrants serious investigation. On a saddle, a rail or a shell is either broken or it’s not. Pretty straightforward. But mechanics don’t mess around when it comes to handlebars, frames, forks and wheels. When in doubt, change it out!