Tektro Oryx - again

[djnotts]

Recently acquired a Jamis Aurora, v little used, vgc, v good price. Chosen for being a triple and having bar cons.
Oryx brakes pretty poor.
Checking tensions revealed that I could barely move the arms by hand. Had to drift them off the bosses with a mallet. Totally dry - from new I guess (as was seat post).
Made a large improvement in braking. Bettered further with longer V brake pads (Clarks finest!).
Rear better than front despite longer cable. The hanger is lower/nearer the "grd on the rear so I am guessihat that might be the "difference"?
Insufficient inner wire to lower straddle without a new one. Is it likely to be worth the hassle (assuming fail to thread it without removing ba

r tape!)?

[cycle tramp]

All things being equal 'yes' - if only because in doing so, you will then have the knowledge to know if its worked - and if it hasn't at least you will then be able to answer the next questions... 'do I dislike these brakes so much that I am prepared to replace them with something else?'

[djnotts]

All things being equal 'yes' - if only because in doing so, you will then have the knowledge to know if its worked - and if it hasn't at least you will then be able to answer the next questions... 'do I dislike these brakes so much that I am prepared to replace them with something else?'

Sounds right, although I have read nothing (of lots!) that suggests that any other cantis are guaranteed to be "better" in any particular situation. They're already about acceptable, what little I understand of MA implies that lowering straddle to give a >90 deg angle when "off" and 90 deg when applied could improve that.

[Rob D]

FWIW, my wife and I have Oryx brakes on our tourers. We have longer pads - and maintain the brakes carefully. Not perfect in rain, but otherwise find them pretty good.

[djnotts]

FWIW, my wife and I have Oryx brakes on our tourers. We have longer pads - and maintain the brakes carefully. Not perfect in rain, but otherwise find them pretty good.

Yes, logically, nearly 50% longer pads make a noticeable difference. Even with my weakened hands and drop levers I can now lock the rear!

[slowster]

This was the definitive thread on the issue of straddle cable height - viewtopic.php?t=57410, in particular cyclenut's/CJ's posts.

[djnotts]

This was the definitive thread on the issue of straddle cable height - viewtopic.php?t=57410, in particular cyclenut's/CJ's posts.

Thanks for that, but a quick skim reveals that I can follow very, very, little of the maths. If 0 level in 1965 covered such things I have long forgotten it.
Cantis are clearly, as I have always thought, the work of a devil!
If the bosses were wider spaced I would just go Vs. I shall try changing and lowering the straddle hanger ..... and beyond that simply accept the danger!

[531colin]

You don’t need to follow the maths…just look at CJs picture of the carefully placed steel rules: where the rules cross shows the length of the arm of a wide profile cantilever with the equivalent mechanical advantage .

Low straddle wire gives higher MA in practice not just in theory. There is enough wire on that front cable, just drop the straddle down to the cable end cap. That’ll make a difference straightaway. The thick pad spacers need to be between the pads and the arms,I think they are already?

Edit. Can’t remember what I’ve got in my bits box at home
Also can’t remember brake post spacing for vee brakes, or when it changed . Oryx feel recent to me, maybe after brake post width increased?

[Norman H]

Colin beat me to it.

Lowering the straddle as far as possible is key to maximizing mechanical advantage (MA) on that type of cantilever brake.

It's also important that the brake pad meets the rim braking surface square on. To achieve this you shuffle around the pairs of conical washers that are supplied with the brake shoes.

[djnotts]

You don’t need to follow the maths…just look at CJs picture of the carefully placed steel rules: where the rules cross shows the length of the arm of a wide profile cantilever with the equivalent mechanical advantage .

Low straddle wire gives higher MA in practice not just in theory. There is enough wire on that front cable, just drop the straddle down to the cable end cap. That’ll make a difference straightaway. The thick pad spacers need to be between the pads and the arms,I think they are already?

Thanks. I must study that photo more carefully.
Guess I can gain 1/2" with existing wire.
Yes, wider spacers on rim side.
And being v familiar with Vs I understand pad/rim contact!

[531colin]

Measure the brake post separation on Vee brake and Tektro bikes
I can’t remember it all.. on the old “narrow” posts front and rear spacing varied?
Too long ago!

[djnotts]

Measure the brake post separation on Vee brake and Tektro bikes
I can’t remember it all.. on the old “narrow” posts front and rear spacing varied?
Too long ago!

Yes, on the 2019 Jamis the f & r spacings are slightly different. The f at c.80mm is the narrower and probably just about wide enough to be ok with some modern Vs. STX RCs probably the best fit.
I'm just trying to avoid hassle of changing brake levers!

[djnotts]

Dropped straddle hanger as far as possible with existing wire. Short test round the block and it DOES seem to make a noticeable further improvement.

[Jdsk]

20230928_142740.jpg (72.49 KiB) Viewed 557 times

[djnotts]

Thanks!
As far as I can judge, now 90deg brake applied, c125 deg slack.