Technical FAQ: All about tubulars

Tubular tire gluing options

Dear Lennard,
Got a question for you about tubular tire gluing. I’m planning on doing a gran fondo next year that involves many miles of tarmac and a few miles of very sketchy dirt, and I’m trying to decide what would be the best tire solution. My old-school brain tells me that a 28mm tubular would be the best performance option. But with the way we glue tubulars these days, if I got a flat it would almost surely mean a DNF, as pulling a well-glued tubular from a carbon rim in the field would be very difficult and overly time consuming. So, my question to you is this: do you know of a tire gluing method that would give the same level of adhesion that we used to get back in the 1970s and 1980s, when we would train on tubulars and regularly swap out tubular tires on the road?
— Bill

Dear Bill,
Well, you could select glue that doesn’t adhere as well. There are fewer glue options nowadays than in the 1970s and early 1980s, and I remember plenty of them that allowed easy tire removal. Remember Tubasti? That held decently but allowed relatively easy tire removal, and it is still available. I haven’t used it in decades and don’t know if its formula has changed. It also stayed tacky, so if you coated the base tape of your spare tubular with it, you could be fairly confident that it would stay on after a tire change. I think Vittoria Mastik 1 or Continental glue hold too well for easy tire removal and dry too hard to have on the spare tire.

The other thing you could do is use tubular gluing tape. Depending on how much adhesion you think you need (and one variable here is rim width; with today’s wider rims and disc brakes, tire adhesion is improved), you can pick the tape that best meets your adhesion needs and your quick-removal desires. And you can bring another roll of tape along with your spare tubular. It is slower than slapping on a pre-glued tubular, but once you remove the tape (often, the tape comes off with the tire, and if not, you can peel it off after the tire is off), you can put on a new layer of tape, stick on a new tubular, and you’re good to go.
— Lennard

Feedback on ’cross tips for rookies

Dear Lennard,

I have to take issue with this line in one of your recent columns:

Consider tubulars rather than tubeless tires for your race wheels. You will be able to run lower pressures without fear of burping air on corners.

I run Hutchinson Black Mamba tubeless on Shimano RS61 on my CX bike. No issues at any pressure. And I’ve even run them flat after putting an inch-long gash in the sidewall (some things are beyond mere sealant).

It’s fair to say that CX is a bit of harmless fun for me and the RS61s are cast offs from my road bike. But I do see lots of people flatting after picking up a thorn and I ride serenely by. I would have thought that insurance easily offset any small weight penalty.
— Stan

Dear Stan,
I understand your perspective, given that you have had stellar results with tubeless CX tires. However, that is not everybody’s experience, and I believe it generally has to do with the rim choice. Furthermore, there is a lot more to the performance difference between tubulars and tubeless CX tires than reliability.

I have been in and seen plenty of cyclocross races in which somebody on tubeless tires came in hard into a sharp corner and burped most of the air out of his or her tire in the turn. I believe that is often the result of using a standard rim with tubeless rim tape. I’ve done a lot of riding on tubeless CX tires at low pressures without ever burping one, but only on two types of rims: tubeless-specific (in my case, a couple of different models of Fulcrum “2-Way Fit”) rims and Stan’s NoTubes rims.

A tubeless-specific rim, like your Shimano RS61 wheels, has a ridge (the “hump”) along the inboard edge of each bead-seat shelf. A tubeless tire mounted on this type of rim is far less likely to burp air at low pressures than one mounted on a standard clincher rim. The hump essentially locks the bead from sliding inward, and it also forms a seal around three sides of the bead, not just two. A standard clincher rim sealed with tubeless sealing tape on it has no bead-retaining hump, is flatter in profile inside, and is slick, all of which tends to allow the beads of a tire at low pressure to slide inward under a high side load and lose air.

Stan’s NoTubes (it’s interesting your name is Stan and you’re a tubeless devotee) rim designs feature a very low internal rim wall — the Stan’s NoTubes Bead Socket Technology (BST), protected by five different patents and licensed to Velocity for some of its rims. I believe that I was never able to burp a tire on these rims because the tire sidewall comes into the top of the rim at a very low angle. On a standard rim with taller rim walls above the bead seats, the tire sidewalls stand up very straight before the tire bulges out above the rim. I think this allows the tire to fold over more easily (and hence be susceptible to burping) than the more rounded tire shape allows on a BST rim.

I also get your point about thorns, since a tubeless tire with sealant in it is largely impervious to them. That said, you can put some sealants (Caffélatex is one) inside of the latex inner tube in a tubular, and it will also be impervious to thorns. I have had personal experience running Caffélatex in tubulars at a race at the Boulder Reservoir where goat head thorns were everywhere, especially in the overflow parking areas; flats were the rule, not the exception, that day, but I didn’t have a single flat despite having goat heads all over both of my tires.

I see the main advantage of a tubeless tire as being the much lower rolling resistance due to the super soft, supple casing of cotton or silk tubulars. There has yet to be a tubeless CX tire that approaches a high-end CX tubular in this department. And when glued on properly, the tubular’s cornering performance cannot be matched by a tubeless tire.

Also, running a clincher tire (tubeless or not), at low pressure exposes the fragile rim walls to denting and bending (aluminum) or cracking (carbon). As for running when flat, I think tubulars will generally give you better security — because they’re glued on — than will any clincher other than perhaps a beadlocked tubeless tire like you have with those rims. And see my point above about ruining the clincher rim when you’re running it flat; a tubular rim is much more likely to survive being run flat than a clincher rim.

And yes, the weight of a tubular rim is also much lower than a clincher rim, and this is rotating weight out at the edges of a big hoop, which, in an event involving continuous acceleration, is far more costly due to the increase in rotational inertia than weight on other parts of the bike. Read the last response on the above link about the three Hummers.

I am quite certain that if you were to do some ’cross racing on high-end handmade cotton or silk tubulars on lightweight carbon rims, you would not be eager to go back to your tubeless tires. Of course, there can be a very wide price gulf between these two options, and given that CX “is a bit of harmless fun” for you, you may still prefer the tubeless tires on the old wheels from your road bike for that reason.
— Lennard

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Technical FAQ: How much rest do older cyclists need?

Dear Lennard,
I read the book “The Haywire Heart” and would like to know how much rest is enough rest. Based on your experience and your age, which I assume is about 60, what is your rest formula?

I am 74 and started running when I was 39, completing 10 marathons, including Boston. I have been cycling for the last eight years and racing five of those years, with the exception of the Senior Games, where I have raced for seven years.

Most of the information and the symptoms described in the book point to me. I had a pacemaker (slow heart) put in about seven years ago, and it was replaced (battery life) this past February. In August, I was told I have AF (atrial fibrillation). I had an Electrocardiogram (EKG), which was not good. That was followed by a stress test which, was “OK,” and I have a follow-up visit to my cardiologists in March.

After reading your book, I have reduced my workout sessions. Now, I do jogging (treadmill, 30/40 minutes), weightlifting/maintenance for 1:15 and ride the trainer for one hour. I do each twice a week and rest one day a week. My cycling on a trainer was 1:30/1:45, three to four times a week unless I rode outside (30 to 50 miles, three or four times a week). Jogging twice a week and weights once a week. Some of the information in the book scares me and is the reason for my question.

My cardiologist probably does not know about an athletic heart or its symptoms. So, I hope to ask the right questions and hope that he will pursue the answers. On the stress test I did, the treadmill went fine, no abnormal heart rhythms, but I do not know what the pictures revealed (several 360-degree pictures were taken). I was told they were “OK,” whatever that means. Rest is something I had not paid attention to until I read your book. If you have any suggestions or recommendations, I would appreciate your input.
— John

Dear John,
This is not a question with a definitive answer, at least not yet in the world’s relatively recent understanding of the relationship between endurance training and racing and the incidence of heart arrhythmia. And you are right to ask your cardiologist; he knows you and is knowledgeable about your heart and what it needs.

Regarding my age, you are right; I am about 60 (I’ll hit that number in June), and I cannot know from personal experience what it is like to be 74 and wanting to train hard. My personal rest formula for dealing with arrhythmia is to have rest be the default, rather than more training. When in doubt, rest; you can’t hurt yourself much by resting, whereas the reverse may not be true.

Lots of research has focused on the amount of rest and recovery needed in order to optimize training loads (and avoid overtraining). There are many methods to detect recovery states, one of the primary ones being heart rate variability. When I was on the national cycling team back in the early 1980s, this was our main tool for determining overtraining or not — checking the resting heart rate (and body weight) first thing in the morning every day. This is a smartphone app I had for monitoring this five years ago when I still cared about optimizing my training before I developed my heart arrhythmia. In the face of your mind coming up with rationalizations for training hard anyway, you might listen to your little handheld computer telling you to back off if needed, rather than you telling yourself to do so based on an elevated morning resting heart rate and a drop in morning weight (indicating dehydration).

You can also take self-assessment questionnaires, which assess mood and other psychological factors, like the Profile of Mood States (POMS); these have been shown to be effective at detecting one’s recovery status. VeloNews will have a podcast on this topic soon with Trevor Connor, who knows a lot about it, hosted by Chris Case (one of my co-authors on “The Haywire Heart”).

While recovery from training is well-studied, it is not necessarily the same thing as the amount of rest required to avoid developing an arrhythmia, which I have never heard of being studied. Still, I believe that the above methods would be useful for optimizing your training without overcooking yourself, and they may also be beneficial for avoiding arrhythmias.

You didn’t say whether you are always in AFib, or whether you have paroxysmal AFib (meaning episodes of AFib that occur occasionally) or persistent AFib. Paroxysmal AFib episodes can last for a few seconds or a few days before the heart’s pacing returns to normal sinus rhythm, often on its own. This condition is fairly common among masters endurance athletes. Paroxysmal AFib and persistent AFib may be treated by “conversion” (cardioversion) back to sinus rhythm with an electric shock delivered via a pair of paddles while under anesthesia (or with drug therapy) if it goes on for many days or longer.

Since you said you were in sinus rhythm on the treadmill stress test, I imagine you are not in permanent AFib. Also, if you were always in AFib, your doctor probably would have put you on blood anticoagulants to prevent stroke, and I imagine you would have mentioned that. Since the heart is not functioning at optimal efficiency when the upper chambers (the atria) are fibrillating (disorganized, chaotic contractions over 300 bpm), AFib certainly decreases your cycling power output.

Sleep is the most important component of rest. If you have any doubt, I recommend you investigate whether you have sleep apnea, which can be done with a sleep test organized by a pulmonologist. Sleep apnea greatly increases the probability of an individual developing AFib, and it largely does that by straining your heart at night while reducing the amount of rest you get. If you are waking up without realizing it due to gasping for air to survive (waking this way 20,000 or more times per night is common in sleep apnea), you aren’t spending much, if any, time in REM sleep and thus aren’t getting good rest when you sleep.
― Lennard

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Technical FAQ: Tips for cyclocross rookies

Questions from a ’cross newbie

Dear Lennard,
I had my first taste of ’cross in 2017 on a touring bike and now I’m hooked, so I purchased a Giant TCX SLR1 to do double duty as my commuter and race bike. The Australian race season in my city starts in April 2018, and I have some tech questions so I can prepare my bike. Perhaps you know some people who are riding the northern ’cross season and can pitch in with their current setups this season?

I’m looking to purchase a set of race wheels so that I can still commute during the week (on the stock Giant rims and road tires) and swap out to lighter race wheels (tubeless CX) for skills training and race day. I don’t want a lot of hassle and adjustment when I swap out.

My bike has the 12mm thru-axles, the front is 100mm) and the rear is 142mm, plus flat mount hydro brakes and an 11-speed SRAM Rival 1X.

1. Is the 12mm thru-axle a standard that includes disc/hub/cassette spacing so I can do a hot swap without caliper or derailleur adjustment?

2. Is it safe to shim a rotor mount on one wheelset to get spacing compatibility between both sets? If so, would you recommend 6-bolt or center-lock for the race wheelset?

3. Is it possible to adjust the hub position and hence caliper/cassette position on the hub axle?

4. Would there be much derailleur adjustment if I went from an 11-36 (commute) cassette to an 11-32 (race) cassette, or would you recommend keeping the same cassette type?

5. If I have a race wheelset and cassette, would you recommend a race chain to go with it? I tend to use KMC with quick links, so swapping is easy.

6. I was also going to get a spare hanger and my LBS said to get it installed and pre-bent before putting it in the toolbox. Any other hot tips for a CX newbie?

Thanks heaps. Also, your book is great! 
— Murray

Dear Murray,
I’m glad to hear you’re hooked on cyclocross and that you get to start your season right after ours ends. My answers are numbered to match yours.

1. Yes, you should be able to swap straight across with your thru-axle wheels, and the derailleur and brakes should line up the same as on the other wheelset. That said, the positions of the rotors may differ slightly. See No. 2.

2. Yes, you can shim the rotors to get both sets of wheels to plop into your bike with no brake rub. I have done this with both 6-bolt rotors and with center-lock ones, although it is easier with 6-bolt rotors. For 6-bolt rotors, you can use shims like these, although you can use separate disc-caliper-mounting shim washers at each hole, or you can even cut your own shims out of a beer can. You can mount 6-bolt rotors (and a shim or two if you wish) onto a center-lock hub with an adapter like this.

I find that if you just have a little bit of brake rub, you can avoid the shimming process completely and just true the rotors to line up the same in the brake. In that case, it is irrelevant whether you have 6-bolt or center-lock rotors. You need a tool like this, ideally with a dial gauge on and a truing fork or two to very precisely get it straight in exactly the plane you want to not have brake rub.

3. No, you cannot adjust the position of the hub on the axle.

4. The best performance will be if you have the same cassette on both wheels. That’s because the chain will have to be considerably longer for the 11-36 than for the 11-32, and you will probably also have to crank down further on the b-screw with the 11-36 as well to avoid chain noise from the upper jockey wheel pinching the chain against the cog. If you then slap an 11-32 on there, there will be more chain slack than need be, and the upper jockey wheel will probably be constrained to stay further away from the cassette than is ideal, so shifting will be more sluggish. The potential for a jumped chain will increase with all of that extra chain slack having to be taken up by the jockey wheels.

5. Yes, if you are not using the same size cassette on both wheels. See No. 4 above. If you had two different chains, you could improve the shifting and chain retention by running a shorter chain with the 11-32. I still anticipate that you’d want to also loosen the b-screw a bit as well, even though you don’t want to do any adjustments.

6. I suppose that’s a good idea, although I have rarely seen the need to bend a new derailleur hanger into proper alignment. Certainly having the extra derailleur hanger is a must. It’s not a terrible idea to have an extra rear derailleur as well.

Here are some other tips for you:
— Mark your seatpost height at the top of the seat binder and check to make sure it does not slide down with repeated jumping on and off of it.

— Tighten your saddle well so it doesn’t slide back or tip back with repeated jumping on and off of it. Mark the rails so you can tell if it has slid back. Unless you’re a really lightweight rider, avoid carbon saddle rails.

— If you have Crank Bros. or Time pedals, set your cleats on the narrower release angle to aid in getting out earlier as you come flying up to a barrier.

— Put steel shoe shields under your cleats so you don’t crack your carbon shoe soles where the rear spring digs into it right behind the cleat. This is especially important with Crank Bros., Look, or Time pedals.

— Consider tubulars rather than tubeless tires for your race wheels. You will be able to run lower pressures without fear of burping air on corners.

Have fun!
— Lennard

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Technical FAQ: Thru-axles, discs, and cranks

Following up on thru-axles

Dear Lennard,
You recently addressed the rationale for front wheel/fork thru-axles when using disc brakes in your column, “Thru-axles and frame stiffness.” I would just like to ask why most frames are transitioning to front and rear thru-axle setups. This requires complete new wheel sets, whereas just replacing the front fork and wheel with thru-axles would be less than half the cost. You made a most eloquent argument for the front wheel change, but why also the rear wheel to thru-axle?
— Matthew

Dear Matthew,
Indeed, in the thru-axle discussion here a couple weeks ago, the majority of the discussion was on the advantages of a front thru-axle. While perhaps less compelling, particularly on road bikes, thru-axles also have advantages over quick releases on the rear of the bike.

I have seen many disc-brake mountain bikes with quick releases where the left rear dropout had become so worn out that the wheel was constantly getting yanked back in the now-widened dropout slot, causing the tire to rub on the chainstay within a short riding distance. I have seen it on bikes with steel dropouts and aluminum dropouts. The stress created by application of the disc brake, combined with insufficient clamping force by the quick release, can really beat up the left dropout.

Analogous to the discussion of the front disc brake and fork dropout damage, when the brake clamps on the rear rotor, the fulcrum of the imaginary lever connecting the tire’s ground contact patch with the top of the tire now becomes at the top of the rotor, rather than at the center of the wheel, and the angular momentum of the rear wheel drives the axle back in the left dropout. Especially when combined with bouncing around on rough terrain along with one of those aluminum, cam-shaped quick-release levers, which generally are incapable of generating sufficient clamping force, the axle can move — in this case, back against the rear wall of the dropout. Do this enough thousand times while braking and riding hard, and you will have ground down the dropout to the point that the axle can wallow all around in there, changing the angle of the rear wheel in the dropout and allowing the tire to move over against the chainstay. A thru-axle completely eliminates the potential for this problem.

I wonder what you mean by your statement about cost. If you were to switch from rim brakes to disc brakes, you would have to get a new bike anyway, and whether the wheels are quick-release or thru-axle has a minor effect on the price. Or did you mean that you could just replace the fork and front wheel and front brake on an existing rim-brake bike and use a front disc brake with a rear rim brake? In that case (see the next question), you would avoid getting a new rear wheel, and the thru-axle discussion would not come into play, as you would still have a rim brake.

Your wish for a front thru-axle and a rear quick-release axle did come true briefly; there was one model year a couple of years ago where some disc-brake cyclocross bikes were coming that way, and there were many years where mountain bikes generally came with a front thru-axle and a rear quick-release axle. Now, most disc-brake bikes have front and rear thru-axles, and I would bet that will be the new normal for the foreseeable future.
― Lennard

Mixing cantilever and disc brakes

Dear Lennard,
I ride and enjoy my 2011 Specialized S-works Tricross, which is fitted with TRP cantilever brakes. I’ve been happy with the canti brakes for ’cross racing and trail riding, though I do recognize the benefits of disc brakes. However, I’m not planning on buying a new CX bike anytime soon. That brings me to my question: what would you think about replacing the front fork in order to run disc brakes? I’d keep the canti brake in the rear.

I’d like to try the Crusher in the Tushar ride in 2018 and have been reading rider opinions on bike selection and course conditions. Being very comfortable with my CX bike, I plan to stick with what is familiar. The description of the descents on washboard roads favors a MTB, so I thought the front disc brake would make the descents safer at speed (as well as allowing for a slightly larger tire up front).

Would you recommend this modification? If so, what are your thoughts/suggestions?
— Chris

Dear Chris,
I think that is a perfectly reasonable solution, for the reasons you cite. See my answer to the prior question for another reason.

The cheapest way to do this would be with a cable-actuated front disc brake, since you could use your existing left lever. That said, the braking performance of a hydraulic disc brake greatly exceeds that of cable-actuated discs. The latter solution would provide you with better braking at the expense of a lighter wallet and mismatched levers.
― Lennard

What’s that little plastic plate for?

Dear Lennard,
I put a Hollowtech II 9000 crankset on my Kent Eriksen bike last spring when I switched to SRAM eTAP and got it working with an 11-36 cogset — partly with your help to try it, against SRAM guidelines for their WiFly. In Sept and October, I rode the bike in Umbria and Abruzzo, Italy to good effect, considering I’m now 70, and I’ve been concerned about arrhythmias even well before reading . The shifting was fine.

But here’s a more technical gear question that, again, the very small local shop mechanic couldn’t help me with. In taking the crank off the bike in Umbria or putting it back on in my garage here a week ago after changing the BB (it grinds), I seem to have broken that little plastic safety plate between the two bolts securing the left crank on the spindle.

I looked in the Zinn road book that I bought early this year (though now I see that it is the 4th edition, 2013) and found no mention of that plate. Drawings don’t show a plate there. Presumably, Hollowtech II came out later than press time for the 4th edition.

The many amateur YouTube how-to videos about the crankset have various advice about how tight to screw in various parts and whether that little plate needs to be there at all. One site called it a spacer. The part had a projection that maybe dropped into the hole that is in the spindle to keep the crank on there if the plastic pre-tension nut or the two bolts all failed.

How important is that plate? Will the crank slide off without it?
— Eric

Dear Eric,
That plate is only important if you ride with those pinch bolts insufficiently tight. If you tighten them to torque spec and check their torque periodically, the plastic safety plate will never come into play.

The plate has a little tab on it directed radially inward, and it is intended to drop into the little hole drilled radially into the side of the spindle a centimeter or so from its non-drive end. As the hole is drilled parallel to the drive-side crankarm, it is also a visual indicator; without looking at the opposite crank, you know the proper installation orientation of the left arm by putting that hole under the slot. The left arm then ends up at the correct 180 degrees to the right arm.

If your crankarm pinch bolts were loose, that tab on the plastic safety plate would keep the arm from sliding off for a little while; otherwise, the arm would come right off while you pedaled. If you were perceptive enough to notice that your crankarm was flopping around before your continued pedaling eroded away that plastic tab, you would save yourself the indignity and damage of having the crankarm come off while riding. If you were to ignore the wallowing around of the crank, however, it would eventually come off anyway, once that tab became worn.

The way to properly use that safety plate on installation and removal without losing it is to remove one of the pinch bolts so that the safety plate can pivot on the other bolt.
― Lennard

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Technical FAQ: How to control two brakes with one hand

After last week’s column, there were lots of suggestions on how to control two hydraulic (or cable) brakes with a single lever. So, this week’s Technical FAQ column is devoted to these reader letters:

Dear Lennard,
Just a quick suggestion for Efe looking to deal with braking with one hand. I have the same problem. I am left-handed, and I do all my shifting and braking using my left hand.

You can see from the picture that I have taken the right STI lever and placed it on the end of the left drop so that the brake lever is almost touching the left brake lever. This allows me to have independent braking, both front and back, allowing me to fully use each brake.

I also have Ultegra Di2, which allows me to modify what each lever does. In my case, both levers shift the rear derailleur, allowing shifting from both the drops and the hoods. To shift the front derailleur my mechanic stripped down a climbing shifter and we attached the stripped down shifter to the left STI lever just above the brake lever. The right side is just a dummy hood, which is completely stripped down.

This system has worked on this bike for 30,000km. The only thing I suggest (like you see in the picture) is to place a sandwich bag on the bottom lever to stop ingress of sweat from hands into the body of the lever. My lever failed after about 10,000km after which I started using the sandwich bag and haven’t had a problem since.

I too am a paracyclist and this setup seems to work for me. Hopefully this could help Efe’s friend.
— Stephan

Dear Lennard,
In response to the question how to set up double brakes on a bicycle with drop bars, I have a couple different theories how to accomplish adequate braking using one hand.

Using mechanical brakes, use a brake splitter where one cable enters and two exit. Think of the old Odyssey Gyro setup used on BMX bikes. The trick will be figuring out where to mount it on a road bike. Of course this would not produce the front/rear bias that Efe was seeking, but it may be a relatively simple solution.

Assuming hydraulic disc brakes are preferred, a single lever set up would require, as you stated, a larger master cylinder to accommodate the increased fluid volume required to operate two calipers. If we pull from automotive tech, it is safe to say the right machine shop could make two separate master cylinders that could be connected together. One would be the rear master cylinder the other the front, each configured to provide the desired front rear braking bias. This is a common set up in racecars.

The next option for a hydraulic system would be to use proportioning valves installed after the master cylinder; this would give a fixed front/rear bias depending on what percent of fluid flows to the front vs. the rear once it leaves the master cylinder. Of course, this setup would also require custom machine work to create the master cylinder and proportioning valves.

In any case, finding the correct braking bias that would cover the most common situations would be the trickiest part of the equation. The center of mass on a bicycle is constantly changing based on rider position, so what works while seated wouldn’t necessarily work as well while standing. If it were me, I would lean toward the side of caution and shoot for a brake bias of F60/R40.
— Carl

Dear Lennard,
Your letter on December 5 about double brakes for a Paralympic cyclist lacked the most obvious answer.

The solution already exists in the automobile industry, where one pedal controls brakes on four or more wheels. The short story is that a balancing system/valve makes the front brake the primary brake and the rear brake function like a secondary brake. The automobile systems are of course more sophisticated and have “split points” to rebalance for harder braking situations. But that is because it is ten to thirty times the mass and 1,000 times more energy to decelerate a motor vehicle than a bike. A simpler lightweight system would be desirable and likely all the Paralympic cyclist needs for his bike.

Possibly all one needs for a simple double brake on a bicycle is the right ratio of large rotor in front and small rotor in back, such as 180/140 or 203/140.

Another simple system on a bicycle might also have a smaller hydraulic port for the rear hose, which will also reduce the force applied to the rear brake.

My reputable reference is a Society of Automotive Engineers PowerPoint they titled “Brake Systems 101.”

Maybe this is how the automobile industry can finally pay back cycling for its invention of the Bowden Cable.

Preferably, a professional engineer with computer-aided design equipment would incorporate calculations to get the ideal pressure balance needed for a bicycle over a broader range of weight/mass. Otherwise, you are in Graeme Obree-like experimental territory. But Campy claims that a single pivot in the rear brake is enough to provide both hands with the feeling that equal pressure is applied by both hands and provides superior braking control.
— Frank

Dear Lennard,
One possible solution to get two hydraulic brakes operated by one lever would be to use a cable-actuated lever and a cable-to-hydraulic converter. You could probably come up with a cable arrangement with a single cable in the lever that gets split to two cables at the actuator. You could adjust brake balance by using separate barrel adjusters to each side of the hydraulic converter. It would take a little fiddling to do the one to two split (basically a “Y” cable) but I can think of a couple of ways to accomplish it with just a little messing around to create a small metal bracket with three cable stops on it (one input and two output).
— David

Dear Lennard,
Perhaps slotting the brake pad material on the rear brake?
— Peter

Dear Lennard,
In response to the question and answer on the braking for the Paralympic cyclist, one solution would be one lever and 2 pistons of differential size to give different amount of braking power front and back.
— Mark

Dear Lennard,
Was just reading about the athlete that needs all the controls to his left hand.

I have done this for a customer with similar issues.

Attached [see above] is my latest iteration (Ver 3.0) of all left-hand controls on a Surly Moloko bar on an S-Works Diverge.

I would think if they used an ergo drop bar, with a flat area, it would be possible to mount the Guide brakes in a similar manner as I have done in the pictures.

Because the Guide brakes are all in-line, it is possible to “stack” the brakes and use the index finger for one brake and the middle finger for the other, up to the rider as to which one is which, of course. Using the RSC version, allows for complete tuning of the brakes.

I will deliver the bike this Friday; test riding the bike at the shop, it works much better than I was expecting. My customer will have full control of the bike with one hand. Front brake, rear brake, dropper post and shifting.
— Jeff Ghiselin – Owner
Stray Dog Bicycles
2340 Sunset Blvd #160
Rocklin, CA

Dear Lennard,
It’s a setup I have never tried, but it might be possible to combine this cable-actuated brake doubler and this cable-to-hydraulic adapter to get the desired result.
— Phil

Dear Lennard,
Just use a [Shimano] Saint lever. It normally pushes 4 pistons in a single caliper, so pushing 4 in two calipers should be fine. I would do XTR Race calipers, or road calipers, since I think they have the smallest volume.

As a side note, I have seen a guy with no hands and one foot riding double black trails at Whistler (Ride Don’t Slide). He had cups made to insert his forearms, and articulated the brakes with dropping the elbow. Fascinating, and motivating.
— Ralph

Dear Lennard,
I was reading your article regarding the braking system for a Paralympic Cyclist. When Efe spoke about a possible single lever dual disc brake setup, I got to thinking. Has anybody (brake manufacturer) considered a setup where one of the brake lines has an orifice in it to increase the required Force to actuate the piston (F=PxA)? Or perhaps, design a dual brake setup where one of the brake lines has a smaller ID than the other. Then when a single lever setup is used, the lever force would apply a greater force on the larger diameter line assuming that the pistons on both brakes were of the same diameter. If two brake lines of equal diameter were used, perhaps a dial-in-adjust flow restrictor could be designed into the inlet of one of the brake lines to allow for brake modulation setup.
— Shawn

Dear Lennard,
I read your piece today regarding a brake work around for a handicapped rider. I recently completed a similar project for a rider with one arm. The rider in question has only his left hand since birth. We fitted a Shimano Dura-Ace Di2 left shifter programmed to operate the rear derailleur. Front shifting is accomplished by fitting a Shimano climbing switch accessible with the same hand programmed to operate the front mechanism.

The braking was a challenge as my customer wanted hydraulic disc brakes. After much research and consultation with Shimano, SRAM, TRP, and others, we determined that the fluid volume in the master cylinder in the single lever is not sufficient to operate two calipers. Our fix was to use a cable-style lever. A cable runs to a cable doubling device which allows the single input cable to operate two separate cables running to each wheel. We then used TRP’s HY-RD brake calipers, which have hydraulic cylinders on each caliper but are actuated by cables.

The setup works perfectly and the client is very happy with it.

— Justin Karbel
Dave’s Cycle
Cos Cob, CT

Dear Lennard,
A potential solution for this special-needs cyclist could be made possible with the Problem Solver cable doubler, if they were willing to use conventional rim brakes or cable discs. I have heard of this being done successfully by a variety of cyclists with special needs.

Could he also mount a rear derailleur fingertip shifter on the left side of his bars?
— Louis

Dear Lennard,
Regarding the gentleman with the hand strength deficiency, I would strongly recommend against splitting the hydraulic fluid from one lever among two calipers. Any attempt to split the braking force over two brakes will reduce the effectiveness of the front brake, which is the critical brake for maximum deceleration. To quote Sheldon Brown: “The fastest that you can stop any bike of normal wheelbase is to apply the front brake so hard that the rear wheel is just about to lift off the ground. In this situation, the rear wheel cannot contribute to stopping power, since it has no traction.”

A setup with braking force split 50/50 front/rear would lock up the back wheel long before locking up the front wheel, and the stopping distance would be longer than the same bike with only a front brake for someone with limited hand strength.

I would recommend leaving the left brake lever connected to only the front brake, and installing a bar-top lever on the left side connected to the rear brake (purely as a backup in case the front brake fails or the front tire flats). Disc brakes would be a good idea if heat management is a concern, since he won’t be able to easily alternate brakes to give rims a chance to cool.
— Brendan

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