To prevent article pages from being miles long, but preserve all the useful questions and answers provided over time, I've decided to copy/paste the website comments to the forum - and "move" further discussions here.
If you can't find the answer to your question in this thread, please open a separate thread with your question/problem, in an appropriate forum section (this is the brakes section).
ericonabike 27/10/2018 at 12:38
Hi Relja,
I,d love to know your opinión on my plan to update an old hard tail, steel frame mountain bike to reincarnate it as a “gravelish” tourer.
I would like to fir bigger wheels than 26″ but it has cantilever brakes and it seems that 27.5 conversion is as far as I can go. I have read that some cantilever brakes have enough up and down adjustability of the pads to allow for the bigger rim. The 27.5″ would be only 12 mm higher from tne brake pivots than tne 26″.
One cantilever model that is recommended for the 27.5 conversion is the Tektro 720 but after reading your thorough article I have some doubts.
First of all, it is a wide profile cantilever, that you describe as obsolete and poor on mechanical advantage.
Second, I fear that the fact that I have to move the pads as high up as possible, that is, further away from the pivot, will also diminish mechanical advantage and braking performance.
Do you think that this conversion is more trouble than what it’s worth? Do you know by any chance a more suitable cantilever model? Am I right in discarding the idea of Vbrakes? Partly because I prefer drop bars.
Thank you
Relja 27/10/2018 at 19:39
As for mechanical advantage, it can be modified by altering yoke angle – so there’s no problem with that, at least not with “old-style” cantilever brakes (no “fixed size” stranding cable). So no need to worry about that – if the brakes are any decent ones (not no-name, flexible calipers).
About the wheels – what is the aim of 27.5″ wheels? What do you want to achieve? 26″ wheels with wide (and hence tall as well) good quality tyres will give strong wheels with comfortable and fast rolling.
28″ wheels (or 29″ as they’re marketed when such diameter wheels are placed on a MTB) do allow slightly lighter wheel (though less strong), but 27.5 is just extra expense for minimal gains in my opinion. So, perhaps a bit of a “Solomon solution”, but I’d recommend good quality tyres with the current 26″ wheels.
ericonabike 27/10/2018 at 21:42
Well, I see your point, but current rims and hubs are worn. I have to replace the wheels any way. And I thought I might gain a a bit of diameter in the process, 25 mm exactly. Probably not worth it if you have decent 26″ wheels, but not my case. I like the way my 28″ bikes roll, 27.5 is as far as I can go because it is a 26″ frame with brake pivots.
I also think, bikes look nicer with bigger wheels, and ride better, I hope the difference is noticeable. 26″ may be doomed to,disappear. There are less and less options and many online shops don’t even sell them any more, many reputed brands stopped making 26″ models. This may be a poor argument, as 27.5 is not very widespread either.
Relja 27/10/2018 at 22:10
In case you need new wheels anyway, things are different, didn’t understand that from the start. I’d still consider 26″ wheels, here’s my thinking:
They’ve been pronouncing the death of 26″ ever since 29ers first came out. But even today, factories make good quality tyres in that dimension as well. In fact, for touring, I’d opt for 26″ wheels since (at least in my part of the world) 26″ tyres are more widely available than 27.5″ and 26″ wheels are stronger (all else being equal).
My first choice would be 28″ wheels, but here that’s not an option. These do roll better. 27.5 is obviously like a “half step” up from 26, but not a very big difference. Even from aesthetic point of view, I’m not sure how nicer a bike designed for 26″ wheels would look with 27.5 – but the looks are 100% subjective, so no arguing there.
You probably could “get away” with 27.5 technically – provided the pads can be moved a bit higher (about 13 mm tops). If that’s the case, you need to weigh the pros and cons. 27.5 leaving less clearance for wider tyres on the frame, which can be a problem if you intend to use mudguards, or wider tyres, for example. Rim and tyre choice also play a role. If you need to change brakes, do currently available cantis (or V-brakes, if changing the levers as well) also have the “extra” 13 mm of pad movement.
Plus side being that 27.5 will roll better with a similarly wide tyre, compared to 26″ wheels.
Gearing is a non-issue with today’s available cassettes and triple chainring cranks in my opinion.
Whatever route you choose, it can be a fun project. Choosing/building new wheels, perhaps even going the dynamo hub route (for touring). While I slightly “lean” towards the 26″ option (if it’s not obvious already), I really can’t say that either choice is outright, 100%, better – not in every aspect. It boils down to your preferences and priorities. So I can’t give you a straight answer “do this”. Most I can do is say what you probably know already: 26″ is more certain to work/fit.
ericonabike 30/10/2018 at 15:33
About the death of 26″ wheels, they will always be around, there will always be a few niches left fir them, like smaller size bikes for children and small people.
But, if I go to good bike shops I don’t see any 26. You can have a look at tne catalogues of the big brands. Trek has three 26″ models whereas 27.5 go up to sixty something. And it is a matter of time untill 28″ is most common in every country. Most bikes are made in China an Taiwan, it is a highly globalised market and trends will spread everywhere.
It is true that a smaller wheel is always stronger, but I have read that today there are better quality materials, rims and spokes and 28″ can be made stronger than before. That’s why you can see wheels with 18, 12 a less spokes.
Geometry is not a problem, clearance, bottom bracket hight, etc. The bike I want to conver is a 1990 mountain bike. A 26″ rim with a 2.20″ tyre and a 27.5 rim with a 1.75″ tyre have an identical,external diameter. In reality I don’t gain much, I only compensate the loss of diameter when I fit smaller road/hybrid tyres.
I have to her new cantilevers with enough adjustability. Tektro cr720 are recommended for this conversion and there are more options, many made for the cyclocross market. My fear, and my original question, was that moving the pads to the far end, away from the pivots will di inish tne mechanical advantage. Cantilevers slteady have a bad name as the least powerful of all brake varieties, l don’t know it the bad name is really deserved. My fear was whether I can afford to loose mechanical advantage in a brake that is already suppose to be just about adecquate got a loaded touring bike,
Cheers
Relja 30/10/2018 at 15:39
Mechanical losses from moving the pads upwards will be compensated by altering yoke angle. I wouldn’t worry about that too much.
You could also try v-brakes (would require changing the brake levers as well), provided they allow the pads to be moved high enough for the larger rim diameter.
Relja 22/02/2020 at 12:59
Just in case – to avoid any misunderstanding: as far as brake levers are concerned, any road, or cantilever brake levers are compatible. Regardless of the type of cantilever brakes used.
Concerning the brake calipers: the system is not digital (of course, as you have obviously noted in your comment – saying the calipers seem like “medium to narrow profile”), so there’s no cut in stone limit, like: “from this – to this width the brake calipers are medium profile”, or “from this to this angle the brake calipers are wide profile” etc.
The model shown in the picture, with the yoke cable setup shown in the picture, looks like a good starting point for setup. The brakes come closest to medium profile for all I can tell. I would start with a yoke angle at about 40 degrees and tune from there.
First testing for brake lever travel (making sure to take out any cable slack first of course by using adjustment barrel on the brake lever, or near the brake housing stops – if one is available/exist on the bike).
Then I’d make a controlled hard stop (in a safe environment) to test for the stopping power (i.e. the level of mechanical advantage). Of course, any increased mechanical advantage, gained by increasing the yoke angle, will result in longer lever travel – so it is a trade-off (I prefer shorter lever travel, with pads staying closer to the rim when brake levers are released, but my hands are rather strong AND I usually use only two fingers for the brake, so don’t like the lever pinching my two smaller fingers still left on the bars).
It is a bit of a trial and error. A bit more so than V-brake tuning, since with cantilevers, depending on the anchor cable length and angle, mechanical advantage changes, along with lever travel (while with V-brakes, it generally boils down to adjusting the desired lever travel and not much else). But once you get a desired setup for the given calipers, you can measure, take note and know how to easily and quickly do it the next time (yoke angle length and angle).
Not sure if this is of much help. Cantilever setup is nothing mysterious, nor completely guess work, but, at least in my experience, there is no getting around some trial and error for a “perfect setup” (according to one’s preferences). The info given in this post is, again, in my experience, a good starting point. Meant to keep trial and error hassle to a minimum.
In fact – this is more thinking out loud – it could be a good idea if people reading this and configuring their cantilevers, could send pictures of their setup (and lever and caliper model if available), yoke cable length and angle, along with their achieved brake lever travel (according to their preference) and feedback on the stopping power, rim clearance and brake lever travel.
Would take some figuring out, but surely in time I could assemble a searchable table depending on the caliper model – with the desired mechanical advantage/lever travel setup examples.
Ben 09/10/2020 at 20:44
Hey there Relja, first off, this post is great! It has all more information than I have been able to find anywhere else after days of scouring the internet.
Some potentially helpful backgound info before I ask my question: I run Tektro Oryx 99A brakes. They came with the used 2014 bike I bought in summer 2018. They have slowly been decreasing in breaking quality since I got the bike and my bike shop hasn’t been a ton of help as the guys I have talked to simply don’t work on cantis much. I have been reading users manuals and manufacturer’s instructions, in addition to watching Park Tool and GCN tutorial videos for canti adjustments/tuning and haven’t been able to find the info I am seeking.
I have tried adjusting my cable tension, spring tension, and used all three of the holes for the spring base pin, but my front left canti still doesn’t have enough spring tension to come off of the rim after I release the lever. If I take the quick-release cable off of the canti, it springs off the rim immediately. It seems the spring tension has somehow been compromised, because no matter what combination of spring/cable tension I have tried, I still wind up with a left canti that can’t spring back against the force applied to it by the right canti spring and brake cable.
Do I need to just buy new cantilevers?
Can I replace the spring?
Am I missing an obvious adjustment?
I would greatly appreciate any advice you could offer and I am hoping that you still monitor this post!
Cheers,
-Ben
Relja 10/10/2020 at 08:18
Hello Ben,
Several problems mentioned here. I’ll discuss them both.
1) Brake’s fading performance
Possible problem causes:
– Pad wear alters the angle, affecting mechanical advantage.
Adjustment should solve this one.
– Grease/dirt on the pads and rims.
Solution is cleaning the rims using 90+ % alcohol (here it’s available in those huge shops – super/hyper markets as they are called – rather cheaply).
And cleaning the pads with it, perhaps first grinding them using a file, or some sandpaper. Kind of brake pads I recommend (similar models exist for V-brake types of brakes, it’s the 2-piece system that makes the difference).
2) One side of brake caliper not retracting
It happens only when the cable is attached – if I understood correctly.
That leads me to a conclusion that spring force on one side is a lot greater than on the opposite side. The brake model has screws for fine-tuning the spring tension.
Changing the hole where the spring is engaged in the frame (three holes usually) doesn’t help? Changing the hole makes a huge difference in spring’s tension. So if changing that doesn’t help either (a lot more coarse method than using the adjustment screws at the calipers), then I suspect one of the following:
– Dirty/stuck bushings.
Disassembling, cleaning, and greasing the mechanism could help.
– Damaged spring, or the inside of the caliper, the place that provides resistance to the spring (frame hole is one side, the other side is against the adjustment screw – that can get damaged/misaligned, so the spring is no longer held in tension on the inside).
– Spring loosing tension by a huge order of magnitude – least likely.
I hope this helps. Do let me know what you try and figure out.
Regards,
Relja
Lez 11/04/2021 at 20:25
What a great post and dialog. Thank you very much. Given me lots of tuning advice.
Roger 30/08/2023 at 13:20
Larger dia wheels are technically better. The penalty for larger wheel dia has always been the weight factor and greater moment of inertia. However with newer tech we have lighter weight alloy construction or even carbon. These new tech rims do not have to sustain brake wear since they use discs which are steel.
The result is a better bike with around the same overall weight as the older 26″.
Just like the older petrol vehicles are phasing out we will see a trend to larger dia bicycle wheels … but hopefully after my time.
If you can't find the answer to your question in this thread, please open a separate thread with your question/problem, in an appropriate forum section (this is the brakes section).
While I slightly “lean” towards the 26″ option (if it’s not obvious already), I really can’t say that either choice is outright, 100%, better – not in every aspect. It boils down to your preferences and priorities. So I can’t give you a straight answer “do this”. Most I can do is say what you probably know already: 26″ is more certain to work/fit.
