Advice on lever pull on my mechanical disc brakes

[Vladimir]

Hi all,
So I've had a Verenti Substance since last year.
It doesn't get much use, mostly due to too many bikes; but another problem is one of classic operant conditioning.

Whenever I use the bike for anything other than very short rides, my index fingers hurt. It's from having to pull hard on the brake levers to operate the brakes as I want to. Mostly the pain is in the right index finger.

The levers are Sora, the calipers are Tektro Mira.

Questions is, what can I do about it?

If I upgrade the front caliper to a BB7, will that help?

TIA

Vlad

[alexnharvey]

I am no expert on disc brakes and in fact have only used them a few times.

Nevertheless a few questions.

Do the cables move freely and are they well lubricated and well routed?

What pads are you using and for how long?

Since pads and cables are cheaper and easier to replace than calipers these might be worth trying first.

I wonder about your hand and overall positioning on the bike as these could also be factors. Is it a stretch to brake and to reach the brake lever, either for body or for your hands? Are you primarily braking from the hoods or from the drops?

[Brucey]

best to get someone else to ride the bike and see if the lever force is too high or not. Note that recent (launched post-2008) STIs pull more cable than older models, so require more force at the lever. There doesn't seem to have been a change in cable disc brakes to allow for this.

Disc brakes can be hard work because

a) the cables are not lubricated properly (very common on new bikes)
b) the pads are rubbish (ditto)
c) the pads are contaminated (ditto)

I think that BB7s ought to be a better brake but not that much better than well-set miras tbh. Condition, set up and pad type are far more important.

cheers

[Vladimir]

As always Brucey, thanks for the valuable info.

a) - fair enough, and this problem probably further compounded by the bike being a CX bike and as such - has fully enclosed cables, so extra places for it to rub. Would it be worthwhile getting new cables and ensuring the lubrication is top notch? I'm pretty sure I have a spare brake cable, and somewhere in the garage I have the fancy version of lithium grease (PTFE grease?).

b) - yes I was reading around the net and lots of people were saying this, so I have ordered some replacement pads. Sintered, I think. Was a little difficult finding ones that are compatible with Tektro Mira, seems they change the names every year or something? Either way they're in the post.

c) hopefully sorted out with new pads.

Thanks

Vlad

best to get someone else to ride the bike and see if the lever force is too high or not. Note that recent (launched post-2008) STIs pull more cable than older models, so require more force at the lever. There doesn't seem to have been a change in cable disc brakes to allow for this.

Disc brakes can be hard work because

a) the cables are not lubricated properly (very common on new bikes)
b) the pads are rubbish (ditto)
c) the pads are contaminated (ditto)

I think that BB7s ought to be a better brake but not that much better than well-set miras tbh. Condition, set up and pad type are far more important.

cheers

[Mr Evil]

The specs shows that it might have either 140 or 160mm discs fitted, depending on the year. Disc size has a significant effect on braking power, with 140mm being a bit wimpy.

[Vladimir]

The specs shows that it might have either 140 or 160mm discs fitted, depending on the year. Disc size has a significant effect on braking power, with 140mm being a bit wimpy.

Fantastic point. My handy pink ruler confirms that they're 160mm. so there's potential