Do Interrupter Brakes reduce braking performance from the main levers?

[Oxford_Guy]

Do Interrupter Brakes reduce braking performance from the main levers?

In an attempt to improve the braking performance of my wife's Ridgeback Voyage Tourer, which has always had very poor braking performance and a spongy braking feel, I'm planning to replace the current Tektro Oryx canti brakes with Shimano CX50 cantis running Swissstop Flash Pro BXP pads (in Shimano Ultegra brake shoes), which I've been very impressed with the performance of on my Hewitt Cheviot (compared to running Tektro TK720s), although part of that is due to the Shimano BL-R400 brake levers I'm now using.

My wife wants to continue using the Shimano Sora STI levers, even though I know they don't have the best mechanical advantage for cantis, but we're wondering whether to keep or ditch the interrupter brakes on the top of the drop bars. On the one hand, I know my wife does use these a lot (partly because they seem to brake better than the main STI levers...) and I think feels safer having them there, but could these be one of the reasons why the braking performance on the STI levers is so poor? Would leaving them out of the system give better braking from the main STI levers? If so, I think she'd rather have better braking on the STIs, rather than having both sets of levers.

NB: will also be replacing both the inner brake cables and outer brake housings with new genuine Shimano parts, as think they're pretty worn too, at least the outers are.

[Kim]

Seems to me that when they're not being operated, they're basically just a join in the cable outer (as per an in-line adjuster or similar), which shouldn't have much of an effect once bedded in.

Most of the problems with the things seem to come from the requirement to stretch the cable outer, and a general lack of room for doing that sort of thing on the top of drop bars, but that makes the inline lever crap, not the main ones.

You can get widgets that fit inline to split the cable and allow multiple levers (or indeed shifters) to pull a single brake.  But that still acts as a join in the outer of the primary cable run, so I don't think it would improve matters.

[Brucey]

interrupters cause a little more cable friction and do reduce braking performance slightly. If they are used primarily it isn't unusual to find that the cable wears most where it exits the interrupter lever.

All things being equal the CX50s will be more powerful than the Oryx cantis but either can vary with setup more than the difference between them, if you see what I mean.

If the STIs are for gen1 STIs then they will work pretty well with the CX50s, but if they are a model that was launched post 2008 they will (with just one exception) have NSSLR cable pull and the braking will be good but not spectacular.

Might I suggest that you set the bike up with new cables , left overly long, but without the interrupters? See if the brakes are adequate, good or excellent, and then you can fit the interrupters if they are good or excellent, knowing that you have a little in hand, as it were.

 Having left the cables overly long they can usually be trimmed and rethreaded, even if the cable ends got mangled in the pinch bolts .

Obviously if the brakes are still poor then you will have to do something different anyway.

cheers

[Kim]

Might I suggest that you set the bike up with new cables , left overly long, but without the interrupters? See if the brakes are adequate, good or excellent, and then you can fit the interrupters if they are good or excellent, knowing that you have a little in hand, as it were.

Excellent advice.

[Oxford_Guy]

Thanks everyone who's replied, some useful info. The Sora STIs are definitely post-2008, I'm afraid. I got Warlands bike shop in Oxford to setup the CX50s on my Hewitt and they did a good job, I think (interestingly the front CX50s are using tbe longest spacers, whereas the rear I think are using the medium-length ones - not sure if that was due to clearance issues with the rack at the back, or just to have a higher MA at the front). Think the Swissstop Flash Pro pads also make quite a difference.

If I was to leave off the interrupters for now, how much excess inner cable would I need to get Warlands to leave, in order to have enough to fit them later, if desired?