simon simpson Posted June 3, 2007 Report Share Posted June 3, 2007 I've just been out with Aileen on the tandem. It took me back to the early 90's when serious camping tourists would debate the problems caused by Shimano redesigning the old (90 degree from vertical0 canti into the 1991 model with a 'lo-profile' 30 degree arm. The conversations continued like this, " He's got old stock deores and cable out the top Dia compe levers" The next problem was when people bought bikes with lo-pros and concealed cable levers.Great on day one outside the shop but a night mare in the rain with worn blocks STI at this time was only Dura Ace at about £280 Those with cash bought Magura rim brakes and used bar end shifters..... Drop bar STI / ergo and cantis is great (I use old style 90 degree Campag HP02s bought in 1993 because nobody would buy them) but you need to be aware of the horror of 'lever against the bar while going down the clune, in the wet, and the guy from the bike shop said they worked fine only last week and there's car pulling out ahead' realisations..... So..... point 1: there's no adjustment screw to move the brakes into the rim when the pad wears on many models point 2 mechanical advantage and cable travel on these items are not necessarily compatible- i.e. almost never- see sheldon brown below and the ctc letters that follow it point 3 if a bike shop does it they'll fix it up and it will work with new blocks, on the flat outside the shop, in the dry.... Dia compe produced dedicated (non sti) lo-pro canti and v levers...some people say they work... aTravel Agent is the usual solution ; http://www.billys.co.uk/english/group.p ... mt2tms9fl2 as you read down you'll see the reference to the 'lever against the bar in the wet' scenario Sheldon Brown on this one: (http://www.sheldonbrown.com/canti-direct.html) main bit below: Brake Levers for Direct-pull Cantilevers Direct-pull cantilevers have double the mechanical advantage compared with traditional brakes, so they require special brake levers. Direct-pull brake levers pull the cable twice as far, half as hard. The lower mechanical advantage of the lever compensates for the higher M.A. of the cantilever. It is not generally safe to mix and match levers/cables between direct pull and other types for this reason. Conventional brake levers used with direct-pull cantilevers will usually not pull enough cable to stop in wet conditions without bottoming out against the handlebars. In dry conditions, they either won't work, or will grab too suddenly. Direct-pull brake levers used with any other type of brakes will feel nice and solid when you squeeze them, but due to their lower mechanical advantage you'll need to squeeze twice as hard to stop as you should, so unless you are a lightweight rider with gorilla-like paws, this combination isn't safe either. To make a brake lever with low enough mechanical advantage for direct-pull cantlevers, the cable must run twice as far from the lever's pivot point. This is easy enough to do with levers for straight/upright handlebars. Levers for drop handlebars are harder to configure for direct-pull brakes, and currently, there's only one drop-bar lever made that's compatible, the Dia Compe 287V. Since most newer drop bar bikes use Ergo or STI brake/shifter units, direct-pull cantis are not generally a good choice for drop-bar applications. Drop-bar Workarounds If you want to use Ergo or STI brifters with direct-pull cantis, there are two workarounds available: You can use a pulley-device, such as the QBP Travel Agent. These are a bit of a hassle to set up, but do work. If you have a bike with skinny tires and no fenders, there are "shorty" direct-pull cantis that are more-or-less compatible with drop bar levers. Neither of these systems is ideal, and neither is really any better than traditional center-pull cantilevers. It is , of course, a hot topic in the ctc... Mini-Vees – 2004.01 I wish to improve the brakes on my 1997 Dawes Galaxy. It has Shimano Deore cantilevers, whereas my road bike has Tiagra dual-pivot sidepulls and much better braking. I read in Cycling Plus that mini V brakes will work with drop barred bikes. They reviewed a Planet-X Kaffenback with Tektro Mini Vees which appeared to work well. They are not very available in bike shops, but they do seem an answer to braking on drop barred touring bikes with large tyres. Ben Bate – Edinburgh Standard vee-brakes have 100mm vertical arms pivoted some 25mm below the rim. Subtract a bit for the cable “noodle cradle†etc. and that leaves 70mm of clearance for tyre and mudguard. Allowing a 50% margin for the latter, that’s about right for a 47mm tyre. That brake is designed for a 25mm cable pull. Drop handlebar levers pull only half that. So a mini-vee with 50mm arms should work okay. But that would leave only 20mm for tyre and mudguard! So mini-vees are a compromise, with arms about 2/3 the height of a standard vee. They give no more clearance, and neither do they work any better with drops, than a medium-reach dual-pivot sidepull (as distinct from the normal, ultra-short-reach variety). I tested an Orbit Harrier with Tektro Mini-vees in October 2000 and found that these brakes limited the section of tyre that could be fitted to 25mm with mudguards. I also observed that, whilst braking required but the lightest of touches, the pads didn’t move far before the lever bottomed out – requiring perfectly true wheels and frequent brake adjustments. I thought Orbit would soon abandon the experiment, and they did. So mini-vees are not the best answer unless the question’s really weird (like a racing bike with cantilever braze-ons, like the Planet-X Kaffenback) which probably explains why you don’t find many in bike shops! They are certainly not the answer for a Dawes Galaxy. For that you’d better stick to cantis. Chris Juden For a confirmation that Mini-Vees are not the answer even on a Planet-X Kaffenback, here's a query I received 2005.12: I recently bought a Planet X Kaffenback and am generally very happy with it, but there are two issues that you may be able to shed some light on. Firstly, the bike is fitted with mini V-brakes combined with drop-bar brake/shift levers. Whilst the brakes are very effective with the blocks set up a hair’s breadth from the rim, any tiny deviation in the trueness of the wheel causes the pads to rub. If I set the brakes up so as to clear the rim, then they fail to bite until the lever is pulled back almost to the handlebar. I stress that the wheels are actually very straight, with an almost imperceptible wobble which I have tried to fix wit a spoke key. Do you, by chance, know any tips that could help me solve this problem? Geoff Wood – by email I suggested some decent cantilevers! J D Sonley, of Gargrave N. Yorks, was descending a twisty hill on his Dawes Discovery when the front Tektro direct-pull brake suddenly failed. Fortunately he was still able to stop the bike by a combination of rear braking (not so effective on a steep hill), foot dragging and swearing! Upon examination the slot in the end of the "stirrup", that is supposed to retain a nipple on the end of the "noodle" (cable guide tube) was found to have opened up, presumably under the force of braking, letting the noodle pop through. This is not an isolated freak incident. I have recently been in correspondence with the operator of a cycle hire business, who in the last couple of years has encountered at least 20 similar cases of complete or partial failure of the noodle stirrup. Enquiries amongst the cycle trade reveal that this is a common occurrence with cheaper brands of direct-pull brake and the photograph shows a collection of failed brakes (the slot is not supposed to be any wider than a cable) from Alhonga, Apse and an unidentifiable brand in addition to Tektro. The stirrup has a slot, rather than a hole, so that the noodle and cable can easily be detached and the brake opened up to facilitate wheel removal. Some other brake-release mechanism might be preferable, however it would appear that the design is adequate when not abused and/or when the stirrup is made from high tensile steel. (I have yet to see a genuine Shimano V-brake failed in this way.) The cables of failed brakes often show evidence of snagging on something, for example the frame tubes in event of the handlebars spinning around – which often occurs in a crash. An upward or sideways yank on the cable will easily lever the noodle completely or partly out of the stirrup; so that firm application of the brake may later force it though the distorted slot. Note that Mr Sonley had a spill on this bike (in a slippery ford) a few weeks previously. If you have this sort of brake on your bike, check that the slot in the noodle stirrup has not become any wider than the inner cable. On cheaper brands the steel is soft enough that you may be able to tighten the slot just by squeezing with pliers! This worked for Mr Sonley, who also tightened a strong zip-tie around the end of the stirrup so it couldn't open out again, enabling him to continue in relative safety and later replace the offending brakes with something of higher quality. Chris Juden Canti – levers – 2006.09 It may be of value to run an article on the dangers of mixing V-brake levers with Canti or caliper brakes, as there seems from my experience to be a dangerous lack of knowledge on behalf of retailers as to the difference between these systems. I will explain. I was recently given my nephews old bike for my son. Before letting him ride it I serviced the bike and made sure everything worked, however one thing didn't: the brakes were seriously under powered, dangerously so. I tried everything, but nothing made them better. My sister informed me new levers had been fitted by a reputable bike shop as the originals had been broken. On closer inspection I realised they had fitted V-brake levers, which pull much more cable than canti levers and thus reduce the pulling power of the lever. As the shop that fitted them is a long way from my home I decided simply to fit a new pair of levers. But when I tried to buy some all the local retailers offered were V-brake levers, saying there was no difference, one assuring me he was a mechanic of 15 years and thus "knew everything". Apparently not! Maybe I'm just very unlucky, but there seems to be some ignorance as to just how different V-brakes are and perhaps something in your publication could help alleviate this. I eventually got a second-hand pair of levers and the brakes now work perfectly. Peter Greenhalgh Reversing V-brakes – 2003.11 It seems a pity a front V brake cable enters on right as this make the cable bend in an S shape rather than a reverse C shape(when front brake lever is also on right). Is a Travel-Agent pulley wired for no cable travel increase any more efficient than the cable noodle? Would mounting V brakes on the rear of the front fork be better because the mounting bolt would no longer be subjected to braking forces? Alan Bradley – Belfast The S-bend doesn’t usually seem to be a problem, however the Travel-Agent is a good noodle substitute – those tubes can get sticky with use and since the cable merely passes around the larger pulley, there will be little risk of fatigue. Most of the world, of course, has the front brake lever on the left. (In Britain we have a noble tradition of zigging when everyone else goes zag, but we can’t expect Shimano to cater for that!) Quote Link to comment Share on other sites More sharing options...
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