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#11
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Long Brake Levers
On Wed, 21 Mar 2018 19:44:01 -0700, Jeff Liebermann
wrote: On Wed, 21 Mar 2018 21:20:19 -0400, Frank Krygowski wrote: That probably sounds terribly risky to some people, as in "But what if the lever breaks at the repair???" I'm sure the TIG welding will hold together if there's sufficient penetration. The epoxy glue job is a bit risky depending on temperature. The difference between the coefficients of thermal expansion for aluminum at 23 PPM/C and epoxy[1] at 95 PPM/C could easily tear apart the glue joint when hot or cold. Looks like Masterbond has several low CTE range epoxies: https://www.masterbond.com/properties/epoxies-low-coefficient-thermal-expansion which are a bit too low but should work. If that's too much work, just mix in some powdered aluminum into the epoxy mix, and it should bring the CTE of the epoxy down a little. If that's still to much work, use the largest diameter roll pin as possible. But in any normal use, the force on a brake lever is quite small. A strong person can bend many designs fairly easily. I did that on the levers on my wife's touring bike, to better fit her smaller grip. They don't have to be super-strong because you'd go over the bars if you squeezed too hard. Agreed. I don't think grip force is going to bend or break the levers (under normal use). More likely, impact damage from dropping the bicycle on the brake levers will break the joint. Epoxy is rather brittle and will crack before it bends. If that's a problem, a thin strip of aluminum, glued over the joint, should help protect the glue joint. [1] MG Chem 9200 structural epoxy adhesive: https://www.mouser.com/ds/2/265/tds-9200-2parts-1149953.pdf A set of epoxy adhesive 832FX-450ml costs $46.03. A set of XLC brake levers Brake Lever set for V-Brake BL-V05, at Amazon is $12.59 :-) -- Cheers, John B. |
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#12
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Long Brake Levers
On 3/21/2018 3:41 PM, Jeff Liebermann wrote:
On Tue, 20 Mar 2018 13:45:06 -0700, sms wrote: On my DaHon Speed TR folder, it had brake levers, branded DaHon with a longer handle than other levers I've seen, about 1" longer. One of the levers broke in half and I haven't been able to find a suitable replacement. No clue on a replacement, but if you still have the remains of the old lever, it can be repaired in various ways. I had one I fixed by drilling both sides of the break. On the thick side, I drilled it for an interference fit for a roll pin. On the other side, I drilled it loosely because it's very difficult to get the holes aligned on the same centerline. I then filled the hole and mating surfaces with structural epoxy and allowed to harden for over 24 hrs. I'll see if I can find it and take a photo. However, there's not much to see. Just a crack that goes around the lever. Another way is to TIG weld the two pieces together. I haven't done this, but have seen the results. If it's done professionally, it should look good and hold together quite nicely. You'll probably need to know the Al alloy. My guess(tm) is forged 6061-T6. I don't have them anymore. But there is just no way you could have fixed these given the small surface area and the large amount of force put on levers. I suppose that welding some sort of reinforcing bar would work but be kludgy. Now that I know the description "four finger brake levers" I should be able to find something. These are for linear pull brakes. As someone said, "four finger" is not a very accurate way to specify the length. Looking at pictures online is about the best I can do. The ones that look the best are not available anywhere, the EVO, E-Force Park V. |
#13
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Long Brake Levers
On Thu, 22 Mar 2018 18:17:37 +0700, John B.
wrote: On Wed, 21 Mar 2018 19:44:01 -0700, Jeff Liebermann wrote: On Wed, 21 Mar 2018 21:20:19 -0400, Frank Krygowski wrote: That probably sounds terribly risky to some people, as in "But what if the lever breaks at the repair???" I'm sure the TIG welding will hold together if there's sufficient penetration. The epoxy glue job is a bit risky depending on temperature. The difference between the coefficients of thermal expansion for aluminum at 23 PPM/C and epoxy[1] at 95 PPM/C could easily tear apart the glue joint when hot or cold. Looks like Masterbond has several low CTE range epoxies: https://www.masterbond.com/properties/epoxies-low-coefficient-thermal-expansion which are a bit too low but should work. If that's too much work, just mix in some powdered aluminum into the epoxy mix, and it should bring the CTE of the epoxy down a little. If that's still to much work, use the largest diameter roll pin as possible. But in any normal use, the force on a brake lever is quite small. A strong person can bend many designs fairly easily. I did that on the levers on my wife's touring bike, to better fit her smaller grip. They don't have to be super-strong because you'd go over the bars if you squeezed too hard. Agreed. I don't think grip force is going to bend or break the levers (under normal use). More likely, impact damage from dropping the bicycle on the brake levers will break the joint. Epoxy is rather brittle and will crack before it bends. If that's a problem, a thin strip of aluminum, glued over the joint, should help protect the glue joint. [1] MG Chem 9200 structural epoxy adhesive: https://www.mouser.com/ds/2/265/tds-9200-2parts-1149953.pdf A set of epoxy adhesive 832FX-450ml costs $46.03. A set of XLC brake levers Brake Lever set for V-Brake BL-V05, at Amazon is $12.59 :-) 9200 - Dual cartridge 25 mL (0.8 fl oz) 1:1 STRUCTURAL EPOXY ADHESIVE https://www.ebay.com/itm/MG-Chemicals-9200-Structural-Adhesive-25-mL-Dual-Syringe-/132476402539 $13.50 for 25 mL. However, you do have a point. Considering the tiny quantity needed for gluing the lever back together, a less expensive adhesive might be a better choice. Unfortunately, I couldn't find a cheaper low CTE and low shrinkage epoxy. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#15
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Long Brake Levers
On Thu, 22 Mar 2018 12:41:39 -0400, Frank Krygowski
wrote: On 3/22/2018 6:02 AM, wrote: On Thursday, March 22, 2018 at 12:42:05 AM UTC+1, Joy Beeson wrote: On Wed, 21 Mar 2018 07:05:36 +0100, Tosspot wrote: 4 finger is longest I've seen these days, but be careful, mileage varies and some are closer to 3 than 4. Now that is weird. Thanks to two engineers and a Dremel Moto-Tool, I have child-size brake levers on my bike, and I can put six fingers on the lever. (Not while riding, of course.) How things can change in only thirty or forty years. -- joy beeson at comcast dot net http://wlweather.net/PAGEJOY/ The above message is a Usenet post. I don't recall having given anyone permission to use it on a Web site. Because brakes/cables and housing got so much better that only two fingers are needed to apply enough pressure on the pads to get you over the bars. Technology is marching ever onward. Some day, we'll just have to THINK the word "brake" and we'll go over the bars. Right. With electrically actuated brakes, you can probably do that. Just wear a colander instead of a helmet while riding. The colander picks up signals from various parts of the brain. When it detects the brain wave pattern for "fear" or "panic", it applies the brakes. Patent pending. Won't that be wonderful! Yep, but you don't need to wait until cycling catches up with modern technology. ABS (anti-skid brakes) and anti-lock bicycle brakes are available today. https://www.bikeradar.com/us/road/news/article/pinarello-blubrake-abs-system-launch-48819/ https://www.bikeradar.com/us/road/gear/article/abs-bicycle-brakes-for-e-bikes-first-look-48000/ https://www.cnet.com/roadshow/news/bosch-brings-anti-lock-brakes-to-bicycles/ http://www.sabs-global.com/product.html https://www.youtube.com/watch?v=Xe-U2E6Cw8w https://www.youtube.com/watch?v=ipwu-J9LElI http://road.cc/content/tech-news/213546-italian-company-blubrake-develops-electronic-anti-lock-braking-system I like the ones with the built in vibrator (mechanical modulator). There's nothing like a good massage after a hard days ride. After the safety fanatics have given up pushing mandatory helmet laws, they can easily switch to ABS brakes as the next required safety feature. Full disclosu I've never actually gone over the handlebars. More often, my flight is interrupted by the stem hitting a very sensitive part of my anatomy. Yep, I can definitely see myself installing ABS bicycle brakes. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#16
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Long Brake Levers
On 3/22/2018 8:48 AM, Jeff Liebermann wrote:
9200 - Dual cartridge 25 mL (0.8 fl oz) 1:1 STRUCTURAL EPOXY ADHESIVE https://www.ebay.com/itm/MG-Chemicals-9200-Structural-Adhesive-25-mL-Dual-Syringe-/132476402539 $13.50 for 25 mL. However, you do have a point. Considering the tiny quantity needed for gluing the lever back together, a less expensive adhesive might be a better choice. Unfortunately, I couldn't find a cheaper low CTE and low shrinkage epoxy. Do you really believe that given the tiny surface area and the large forces applied to brake levers that any adhesive could possibly work? You would have to reinforce the repair with some sort of splice. Way too complicated to try to save zero dollars. |
#17
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Long Brake Levers
On Thu, 22 Mar 2018 10:13:11 -0700, sms
wrote: On 3/22/2018 8:48 AM, Jeff Liebermann wrote: 9200 - Dual cartridge 25 mL (0.8 fl oz) 1:1 STRUCTURAL EPOXY ADHESIVE https://www.ebay.com/itm/MG-Chemicals-9200-Structural-Adhesive-25-mL-Dual-Syringe-/132476402539 $13.50 for 25 mL. However, you do have a point. Considering the tiny quantity needed for gluing the lever back together, a less expensive adhesive might be a better choice. Unfortunately, I couldn't find a cheaper low CTE and low shrinkage epoxy. Do you really believe that given the tiny surface area and the large forces applied to brake levers that any adhesive could possibly work? Yes. The glue joint won't be as strong as the original aluminum forging, but should hold together as long as you don't crash the bicycle. If the levers are hollow, a steel reinforcing rod down the center cavity should provide sufficient strength. If solid, drilling and adding a steel roll pin should do the same. The strength is not in the glued butt joint, as you seem to suggest. It's in the roll pin or center rod. Simply slopping on some glue to the broken area and butting them together, isn't going to hold. You would have to reinforce the repair with some sort of splice. Way too complicated to try to save zero dollars. Well, if it's too thin for a pin through the center of the lever, then tacking the pieces together, milling several slots across the broken area, and pounding in a roll pin, should be sufficiently strong. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#18
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Long Brake Levers
On 3/20/2018 1:45 PM, sms wrote:
On my DaHon Speed TR folder, it had brake levers, branded DaHon with a longer handle than other levers I've seen, about 1" longer. One of the levers broke in half and I haven't been able to find a suitable replacement. DaHon was no help in getting a replacement, ever since Pete Mole passed away the company has been in decline in the U.S.. I replaced both of the levers with https://www.bikenashbar.com/cycling/nashbar-deluxe-mountain-bike-brake-levers-ns-adbl-base but the levers are too short. Where can I find longer brake levers? Pretty amazing to search for brake levers. I have seen 2 finger, 3 finger, 3.5 finger, and 4 finger models. It's very hard to find a 4 finger V-Brake/Linear version that is purchasable. Most are caliper and cantilever only. I found two that claim to be 4-Finger: 1. XLC-BL-V05 2. Saccon Shimano Nexus V-brake 4-finger silver / bl (not available in U.S.). |
#19
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Long Brake Levers
On 03/23/2018 12:00 AM, sms wrote:
On 3/20/2018 1:45 PM, sms wrote: On my DaHon Speed TR folder, it had brake levers, branded DaHon with a longer handle than other levers I've seen, about 1" longer. One of the levers broke in half and I haven't been able to find a suitable replacement. DaHon was no help in getting a replacement, ever since Pete Mole passed away the company has been in decline in the U.S.. I replaced both of the levers with https://www.bikenashbar.com/cycling/nashbar-deluxe-mountain-bike-brake-levers-ns-adbl-base but the levers are too short. Where can I find longer brake levers? Pretty amazing to search for brake levers. I have seen 2 finger, 3 finger, 3.5 finger, and 4 finger models. It's very hard to find a 4 finger V-Brake/Linear version that is purchasable. Most are caliper and cantilever only. I found two that claim to be 4-Finger: 1. XLC-BL-V05 2. Saccon Shimano Nexus V-brake 4-finger silver / bl (not available in U.S.). That was my experience. It's not that I don't think 2/3 finger brakes work, but when it's -15 and I'm wearing ski gloves they become 1/2 finger brakes. Added to which, I *like* 4 finger levers :-( |
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