Wow Bill!! Thanks for this! Very helpful.... really appreciate the analysis!
On Saturday, January 18, 2025 at 11:39:49 AM UTC-5 Bill Lindsay wrote: > "if I could confirm the caliper width" > > This depends mostly on you and your setup. The four things that depend > exclusively on you are: > > 1. How wide is your tire, really? There's some objective measurement, > lets call that X1 > 2. What width of brake pads do you require to "clear" that tire? Let's > call that X2. Is X2 1mm larger than X1? Or are you OK with forcing it out > a little, so that X2 is a little bit smaller than X1? > 3. How wide is your rim? That's X3 > 4. How wide do you choose to run the brake pads relative to that rim > width? Some generations of 105 brifters are high mechanical advantage > levers. They pull very little cable. Combine that with things like small > hands and the desire for hair trigger barking and you might run your brakes > super close to the rim. Let's call this X4, which has some relationship to > X3. So it depends on you in two ways. > > The only thing a person with Grand Cru calipers can tell you is how much > the calipers open when you throw the QR from the closed position to the > open position. I've got a bike with Grand Cru calipers. I threw it on the > stand for you and pulled the front wheel. It barely gets out with some > force. A solid whack with my fist and out it comes. Not enough of a > problem to worry about knocking out the brake adjustment, but it's pushing > it. > > My tire measures 33mm actual width. X1 = 33mm > My rim measures 23mm wide. X3 = 23mm > My brake pads with the QR closed measure 26mm wide, 3mm wider than the rim > width. X4 = 26mm > When I throw the QR to the open position, the brakes open up just a tiny > bit to 29.5mm. X2 = 29.5mm > > So the DIFFERENCE between Closed and Open on Grand Cru calipers is 3,5mm > as-measured on my front brake. X2 (29.5mm) is quite a bit smaller than X1 > (33mm) so that's why it is hard to remove the tire. I knew this would be > the case when I pulled the build together and I feel that road bikes with > caliper brakes and wide tires should have a brake-lever QR in addition. My > build uses Campagnolo brifters, which I gutted so they are just brake > levers. I have a QR button, and that button allows X2 to grow from 29.5mm > out to 32mm. That allows pretty easy front wheel removal: the tire just > squeaks past the brake pads with a little friction but I don't have to > whack it, like I would if I didn't have a brake lever QR button. > > If I hypothetically had Shimano brifters and if I wanted to earn myself > another couple of millimeters without ditching my brifters, a few options > would include: > > -run wider rims, increasing X3 and correspondingly increasing X4, which > will grow X2 as well > -consider running the brakes looser from the rim > -consider using the barrel adjuster as an auxiliary QR > -consider running an inline QR mechanism, like the Shimano SM-CB90 > > That's what I've got for you. > > Bill Lindsay > El Cerrito, CA > > On Saturday, January 18, 2025 at 7:45:11 AM UTC-8 warne...@gmail.com > wrote: > >> Thanks for the many suggestions! My Roadeo is currently setup with >> Shimano 105 brifters, so unfortunately the road lever QR functionality is >> not an option. Perhaps I'll look into the Tektro 539 option. I've heard >> great things about the VO Grand Cru's, and think they look really nice too; >> so would love to go that route if I could confirm the caliper width when >> open up with QR. >> >> On Friday, January 17, 2025 at 10:49:34 PM UTC-5 Benz Ouyang, Sunnyvale, >> CA wrote: >> >>> Ryan's recommendation of doubling up on QR with QR on the calipers and >>> QR on the levers is probably your best chance of getting adequate >>> clearance. I have a similar setup with Grand Cru brakes and Campagnolo >>> Ergopowers (with the built-in QR). >>> >>> One thing you didn't mention is what rims you're using. The narrower the >>> rim, the less the QR is able to clear wider tires when opened. As an >>> extreme example, if you're running 30mm rims with 35mm tires, the QR only >>> needs to nominally clear the 5mm difference. However, if you're running >>> super narrow 19mm rims with the same 35mm tires, you're looking to clear >>> 16mm of "tire bulge", which is more of a challenge. >>> >>> On Friday, January 17, 2025 at 2:45:43 PM UTC-8 Ryan wrote: >>> >>>> I have 32mm Stampede Pass tires on my Rivendell Road. I realize they're >>>> not 35mm. I also have Grand Cru brakes and TRP road levers with the >>>> additional QR button, for additional slack on the inside of the brake >>>> hoods. Maybe that combo could work? Don't have a wheelset with 35 mm tires >>>> ready to hand to tell you for sure, however, unfortunately, but maybe >>>> someone else on the list has this brake/lever combo AND >= 35 mm tires and >>>> could tell you for sure. One reviewer on Orange Velo site mentions that >>>> the Grand Cru brakes on their own don't release enough to mount a wheel >>>> with a 35mm tire...but in combo with the TRP levers, they just might clear >>>> your 35mm tire. Functionally and aesthetically they are a nice combo. >>>> >>>> On Friday, January 17, 2025 at 4:00:39 PM UTC-6 iamkeith wrote: >>>> >>>>> I hope I have these model numbers correct and not transposed, but the >>>>> Tektro R539 was originally designed by and for Rivendell, as the first >>>>> "Silver" branded brake. It was designed specifically for this purpose - >>>>> as >>>>> an upgrade for Rambouillets and Romuli and Redwoods, etc, which were >>>>> designed to fit 33-37 tires, at at time when medium-reach brakes were few >>>>> and far between. Tektro eventually started selling them to anybody. >>>>> I'm >>>>> not sure why Rivendell doesn't still carry them, but does still carry the >>>>> even-longer-reach R559. At any rate, they're still available but it >>>>> might >>>>> take some looking to find some in a proper silver finish. I don't think >>>>> I'd ever rave about any caliper brake, but have them on my Ram and they >>>>> are >>>>> fine and do what you are looking for. >>>>> >>>>> On Friday, January 17, 2025 at 2:30:06 PM UTC-7 warne...@gmail.com >>>>> wrote: >>>>> >>>>>> I currently have Shimano BR650 calipers on my Riv Roadeo, and have to >>>>>> deflate the 35mm tires to remove the wheel. I'm looking for >>>>>> recommendations for calipers that would open wide enough for the RH Bon >>>>>> Jon >>>>>> Pass tires I'm using (35mm wide). >>>>>> I believe the Velo Orange Grand Cru calipers would accommodate these >>>>>> tires.... any thoughts on these? >>>>>> Also, not sure about Paul Racer M's?? I appreciate the wisdom and >>>>>> insight of the forum!! >>>>>> >>>>>> thanks! >>>>>> Bob >>>>>> >>>>> -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. 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