sjanzeir

So, I'm looking to uprate the factory V-brakes on my Mu. I've ordered some Jagwire compressionless housings on the way, having taken a closer look at the factory brake arms in action today, I've noticed that there's ever so slight flex in the length between the brake block mounting slot and the cable anchor:



So, are there any stiffer arms that I can possibly replace these with (that are reasonably priced)? I mean, a set of Paul Motolites would be nice, but at nearly $500 for two pairs, I'd be perfectly happy with something a little more plebeian...

hokiefyd 

Shorter arms would presumably flex less, if you'd be open to that option. They'd have less mechanical advantage, but they'd flex less. Otherwise, I think most mass market linear pull brake arms (from the likes of Shimano or Tektro) will be pretty similar in that regard. Most full length ones are in the 100-105mm range. The shorties are about 80-85mm. They're designed to work with short pull brake levers.

frankenmike 

Do they stop good? If so I’d save the money for other upgrades.

SalsaShark

In my experience, if the caliper arms are stiff enough to not flex in use, the seat stays will flex instead. This flex is usually a byproduct of the braking system having more than adequate power available to efficiently stop the bicycle. Linear pull brakes are quite powerful due to the high mechanical advantage of the system. I have not seen the need for compressionless housing, as it might lessen the already twitchy modulation of a bike equipped with linear pull brakes.

sjanzeir

They're better than good; they'll easily send me over the bars. Raw stopping power is not an issue, especially given that I'm still on factory blocks. It's that spongy feeling - particularly in the rear brake - that I'm trying to chase out. Or maybe I've been spoiled by the hydraulic disk brakes on my Hemingway.

sjanzeir

My hybrids, with 700c wheels, run the same exact brake blocks and levers (avid FR-5) on 85mm mini-Vs. I can report that the brake feel is noticeably more positive and solid with pleasingly more precise modulation, and stopping power is just as good. It's that feel that I'm trying to replicate.

sjanzeir

This being a 20" folding bike with a pair of burly, stubby stays that double both chain stays and seat stays, there is very short frame real estate between the rear wheel axle and the brake stud. That said, I could discern some barely noticeable flex near the dropouts - by a much smaller amount than that in the brake arms themselves.

hokiefyd 

I know what you mean. I have a couple of bikes with Mini-Vs also. I'd suggest using those. You'll get a firmer feel with less mechanical advantage with long-pull levers (like Avid FR-5s). These have a pull radius of about 32mm, which is about in the middle of the range for flat bar levers. Shimano long-pulls are closer to 40mm. True short-pull levers will give you more mechanical advantage, but will have a slightly squishier feel (all else being equal). These are levers usually have a pull radius of about 24-29mm.

I never realized how variable the pull radius is on flat bar brake levers until I started measuring it, even among those in the same "class" (such as short-pull or long-pull). You can really dial the feel and mechanical advantage balance with your choice of levers. Go all the way with something like an Avid Speed Dial lever and go mad with it!

sweeks

This is just a stab in the dark... isn't the slightly spongy feeling proportional to the cable length?

Sorcerer

Seat stays can spread, flex apart, when pulling the rear brake because the tubing can be flexible. I discovered this myself on a titanium mountain bike.

The fix was adding an aftermarket "brake-booster". These are horseshoe shaped affairs made of metal or carbon fiber and typically come with some hardware to mount them with.

I ended up with a Shimano booster. I have two bikes that use one each. They are essential as the rear brakes are not functional enough for trail riding otherwise.

sjanzeir

Looked at those, too (I did some of my homework before I posted the question,) but given that this is just a regular folding bike that I ride around town and treat a lot like a BMX and never take it anywhere near an MTB trail, going the brake booster route seemed like taking it a little too far... Anyway, my 30ft compressionless jagwire loop is in the mail; I'll install a length, see what that does and report back.

And let me take this opportunity to mouth off as to just how much I hate internal cable routing - especially on a folding bike. I hated it on my old Raleigh in 1995 and I loathe it now. I despise whomever invented it and thought it was a good idea in the first place. Changing out that outer is going to be a hell of a PITA (don't ask me how I know.)

dsbrantjr

Never Fix A Running Piece.

HTupolev

Yeah, this is basically what brake boosters exist to address.

Avoiding compressionless housing is like deliberately leave air in the lines when setting up hydraulic discs. Flex causing post-engagement movement in the brake lever muddies the waters around the sensation of lever pressure, and can make the point of engagement harder to feel. I actually think that v-brakes have more to gain from low-compression housing than almost any other kind of mechanical brake, because the high mechanical advantage leaves them prone to mushiness.

The idea of de-tuning the braking-power-versus-lever-force curve makes theoretical sense from a certain angle, but I don't think it applies to the circumstance that most cycling equipment is in. Maximal control can't happen if your finger can't easily distinguish force levels, but it can also be compromised by having to put real effort into a squeeze. And bicycle brakes almost never end up on the former side of that curve: for most riders, very little commonly-available equipment is too powerful for a well-fit one-finger action.

Germany_chris

Older XT and up V bakes were pretty stiff
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The ones that look like these. Pad adjustment on them is kinda finnicky but they have plenty of power and stiffness

sjanzeir

Yeah, researching this, I've come across a few discussions about those "parallel push" types. Some people swear by them; others say that they are too complicated to to be worth it.

There seems to be a general consensus, though, that the regular, non-parallel XT/XTR V-brake arms are probably the stiffest ever.

Germany_chris

They could well be I have a set of parallels XT 785/6? and a newer set XT T-780? and never noticed a difference in stiffness but logic say that material science has improved and anything newer will be stiffer. I did go upmarket last year and notice that the more expensive brake is easier to modulate if ultimately having the same power.

Mr. 66

I would not use compressionless housing for brake, one can but that housing would also need to be braided also. The housing without the braiding can blast apart after time under brake use.

bboy314

Hopefully the OP is referring to compressionless brake housing, which has the braiding and is often used for mechanical disc brakes.

sjanzeir

True.

sjanzeir

Update: I installed a length of new Jagwire compressionless outer for my Mu's rear V-brake along with a new inner. I can tell you that there's a noticeable improvement in brake feel with a much better defined engagement point, but now the flex in the V-brake arms appears more pronounced because the old brake housing is no longer there to take up some of the slack. I would've shot a video of the brake arms in action if I had a functioning tripod; I'll get around to it later.

May whoever invented internal cable routing - and whoever thought it was a good idea to design a folding bike with internal cable routing - burn in hell for epoch after searing epoch.

cobba

Have you thought about trying hydraulic rim brakes?

https://www.magura.com/en/components/bike/rim-brakes/

sjanzeir

Of course I have! 😁

sjanzeir

Okay, update time!

I had spent some time looking at pictures of V-brake arms that look like they might be stiffer than the crappy aforementioned Tektros. There weren't very many brand-name brakes that seemed to fit the bill... but these ones from the Litepro official store looked like they could make for a viable test case:





For a fraction of the price of the likes of Bombshell, Bullseye, LDC, and Speedline, no wonder that they look ugly AF! (I had ordered all-silver but they messaged me to tell me that the stock data on their store front was wrong and they were sending red on black instead - that's Aliexpress for ya!)

They were a PITA to install and set up, too (the old YGWYPF adage at work); one arm in particular needed a few taps with the handle of a screwdriver to go onto the stud - and the leverage of said screwdriver to come off; using the middle holes on the pivots to anchor the springs meant that the brake levers would be way too stiff to pull at, so I anchored them on the lower holes instead; the alloy bolts were about to get their hex heads rounded at the slightest attempt to tighten them; despite the (alleged) ball bearings, all four arms seemed to suffer from Sticky Pivot Syndrome; the supplied washers were too large to allow any free pivoting action, so I had to use smaller, brass washers that tightened only onto the inner bearing race; and adjusting the set screws for equal free travel was finicky at best.

But boy, do they work! Stiff as a girder they certainly are, and once I finally managed to set them up properly and take the bike out, they were stellar! Unlike with the factory Tektros that were made of cheese, now I've got some real stopping power that I can actually modulate.

We'll see how they hold up under regular use. What I might do next is get another set, this time in the silver that I originally wanted, and move the red bits from the black ones over to the silver ones, matching the livery of the bike.

One thing's for sure, though: I really, really, need to replace the old, nearly worn out Tektro pads with fresh, quality ones!

Germany_chris

I’m glad you found something that works for you

downtube42

I'm not from a third world country, but I did grow up in an economically disadvantaged neighborhood

I empathize with the use of inappropriate tools and excessive force to turn barely adequate designs into functional items. In the first world advantaged neighborhood where I now reside, there is no activity so satisfying. Using a Park chain tool to break a chain is not nearly as rewarding as performing the same task with a large flanged cast iron bushing pulled from the junkpile, a carpenter's hammer, and a 6 penny nail. However, if I tried reliving that experience now, it would be phony.

Carry on.