Mountain Bike Reviews Forum banner
1 - 16 of 16 Posts

·
Pivoteer
Joined
·
3,445 Posts
Discussion Starter · #1 ·
I have a set of Tech V2s with the floating 203/183 combo with the stock Hope organic pads. I also have a set of Tech M4s with floating rotors and Hope organic pads.

On my M4s, with the bike in the stand,when I pull the levers, they are solid, they come to a complete stop. I can pull the lever with all my strenght and get them to move closer to the bar, but overall, a nice solid feeling.

With the V2s, I am getting a more mushy feeling. I have bleed both the front and rear (also bled the M4s), using the same technique shown on the Hope website, using the same Valvoline DOT4 fluid. My calipers were centered using feeler guages, and the pads are contacting the rotors identically (no flexing in the rotor).

When on the bike, it is not noticable, the brakes are STRONG, infact I have the BPC dialed almost all of the way out (same with the M4s). I have noticed, if I drop in a set of Sintered pads, the levers have a much more positive, stiff feeling to them.

So, my question is this, are the M4s feeling more solid in the stand because they have a larger contact with smaller pistons, so the lever cannot compress as easily? Is it possible that the V2 pistons are strong enough to "compress" the pad material of the organics?

Or, do I need to bleed them again? I have pushed about 30cc of fluid through each brake, the fluid is clean, no air bubbles, and the front and rear V2s feel the exact same after bleeding. I really don't think this is the problem, since both front and rear feel exactly the same.
 

·
Pivoteer
Joined
·
3,445 Posts
Discussion Starter · #3 ·
Diggidy said:
HOPE says to use DOT 5.1, not 4.0. Do the pistons on the V2 move freely or is there any sticking of the pistons?
No issues with the pistons. After a ride today, The lever feel is perfect when riding. The power is crazy. It is more of an issue, or more appropriately a non-issue, when the bike is in the stand.

I am under the impression that DOT4 is just fine. In-fact, many of the Hope experts on here highly recommend the Valvoline fluid. Someone posted a link as well, showing Valvoline having one of the highest dry and wet boiling points. If this is not correct, please correct me. My brakes did not come with a manual, and i have not seen a version on the website.
 

·
Registered
Joined
·
468 Posts
what rotor are you using with the V2 ?
I also noticed that when sitting stationary and pushing the brake while rocking the bike back and forward the brake does some CLICK noise, looks like the pads are moving in the caliper

is that normal ?
 

·
...idios...
Joined
·
5,662 Posts
I also noticed that when sitting stationary and pushing the brake while rocking the bike back and forward the brake does some CLICK noise, looks like the pads are moving in the caliper.
I have this with all of my Hopes, to lesser degrees. The V2 and X2 is the most obvious, having the larger (taller) backing plate on the pads.

tiSS'er, I've always put the slightly softer feeling of the V2 down to a combination of the rotor and the caliper. I get it a little on my SX Trail, where I use a vented rotor, but more notably on my Orange, which has a standard rotor. You can observe the cause most easily with the caliper removed from the bike; take the pads from the caliper, and fill the full width* of the rotor slot with large washers and gently pumping the pistons out until they clamp the washers/spacers. First of all, any compression you felt from different pad compounds will now be removed; so you really should feel a defined stop at the end of the lever stroke (bite point). If you now pull the lever hard, you'll notice that the bite point softens. You should now be able to clearly see the caliper flexing under the force of the compressing pistons. It is this, I believe, which gives the V2 it's slightly different feel; as it is much less noticeable on the M4. (I have Tech M4s on the rear of both bikes).

*it's important that you fill the whole width of the rotor slot on the V2 as the pistons are further apart (to be able to accomodate the vented rotor) than on the other Mono calipers. If you don't fill the whole slot, you'll empty the reserve of fluid from the master cylinder and draw air into the system.
 

·
Pivoteer
Joined
·
3,445 Posts
Discussion Starter · #6 ·
SteveUK,

Thanks for the reply. I feel better now knowing i am not doing something wrong with the bleed, or other issue. I am running the standard floating rotor, not the vented. I have never thought about the caliper flexing, but it makes sense. I am actually glad that they do, or if by design, it is genious. When I was in Whistler, I had a tough time braking the first day as the brakes were coming on so strong, so quickly, I was really losing balance and confidence. After dialing out the BPC, it became very clear that these brakes are beyond anything I have ever ridden. They were simply superb.

Do you see any issue with me running DOT4? I know DOT5.1 is a bit more viscous, but will it really matter?
 

·
...idios...
Joined
·
5,662 Posts
There seem to be plenty of people running certain high-performance DOT 4 fluid - Motul springs to mind - where the boiling points can be better than some other fluids rated at DOT 5.1. I'm a habitual Stendec Crystal DOT 5.1 users because it's what my local shop carries and because I've never had any trouble with it.

I'm afraid that I just don't have knowledge to say that any given fluid (at room temp) is, or could be, responsible for the feel of you lever (at the end of its stroke); but I would be surprised if it is. No matter how viscous a fluid is (up to a point), it's no more/less compressible than the next. A thicker fluid might make the lever slightly more difficult to depress, but once the pads bite then compressionless is compressionless. I'm sure if that is incorrect somebody with an education will set me right.

I've no idea whether or not the flex was built into the caliper design; it's present on all the calipers, though. I would agree with you that it makes sense, as zero give in a system would leave the brake feeling harsh and twitchy. There's good flex and there's bad flex, of course; the flex in the lever clamp of the old Mini lever feels really quite strange to me now, after a couple of years on the Moto and now Tech levers. Hope really have it nailed with the Tech lever; it feels so smooth, almsot servo-driven, and yet so precise; and the BPC and reach adjustments make it so simple to tone a brake up or down, while still being able to balance the feel of both levers, that I sometimes find myself doing it just because I can! Like I said, Hope really have nailed it with this one.
 

·
ride hard take risks
Joined
·
25,423 Posts
The hydraulic line on a mountain bike is very small ID and the construction does not allow much if any expansion under pressure. Back in the early motorcycle era when the hoses were massive rubber expanding hoses you could notice a slight difference in fluids under braking. Today moto hoses are much smaller ID and speeds higher with more caliper pistons and allot of heat boiling fluids. My last brake bleed was with Valvoline DOT4 and couldnt tell the difference from my normal Bel-Ray I usually use.

My HT did a similar thing to me when in the rack it was a bit spongy and I was lazy so just left it being the rear brake. 4 days latter pulled it out of the garage and its all pumped up, didnt try to figure it out just be happy like you did. :thumbsup:
 

·
Registered
Joined
·
468 Posts
Hi Steve! thanks for the very useful information!

another question i just must ask you about the V2s.

i currently have the V2 rear and front on my SX Trail, but with the Avid G2 rotors [very temporary, ran out of funds for the rotors ;)]

what i wanted to ask you - is there any difference in thickness between the standard V2 floating rotor, the mono SAW 6 and the V2 VENTED rotors in thickness?

will there be any difference in the braking feel between the 3 rotors ?

i know that the M6 pads are shorter [the area that actually brakes],
and the V2 pads are massive!

but what about thickness?

which one would you recommend using with the V2 brake ?

thanks!

Eli.
 

·
...idios...
Joined
·
5,662 Posts
OK, well I'm thinking that we need to define some terms here! When I talk about thickness in relation to rotors, I'm refering to the thickness of the steel used to make the rotor. So, the standard V2 is the same as other Hope rotors at 1.85mm. The vented rotor is 3.25mm thick.

The width of the brake track on the rotors (on thus the width of the pad) is 20mm on the V2 and 16mm on the M6. I don't know the track width of the Avid rotors, although I'd imagine it to be closer to, or even less than, the M6. Using a rotor with a narrower track would mean the rotor arms would be catching the pads. This action usually creates buzzing or vibration which can be felt at the lever. How much it affects the brake's performance is possibly a matter of opinion.

If it were me, I'd go with the V2 rotors. I managed to get a vented rotor for less than the cost of a standard floater, so I run that on the front of my SX Trail. It does have a slightly firmer feel "on the stand", but on the trail the brakes are more or less identical. I rarely do descents which would really necessitate a vented rotor; but if you do, then it's certainly worth considering. I have a virtually new 183mm floating V2 which I'd be willing to part with. PM me if you're interested...
 

·
Registered
Joined
·
276 Posts
I have Tech M4s and bled with DOT 4, I was just saying that if he has a bad lever feel, possibly try using 5.1, which is what HOPE says to use on the new Tech models. I believe 5.1 by design is less viscous and was designed for micro-channel systems like ABS, or small inner diameter hosing of our brakes.

I never felt a different between 5.1 and 4 when I switched however.
 

·
Registered
Joined
·
68 Posts
Hey guys,
I have a question concerning the tech v2 /tech m4 brake.
Is it possible to set the bite point pretty early after about 1 cm of lever stroke?
I currenty have shimanos and the free stroke is long, the adjustment makes no real effect. I dont like it when I have to pull the lever too close to the handlebar.
Thanks a lot!
 
1 - 16 of 16 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top