Any mechanic tricks to reduce stiffness of Shimano STI brake lever

[reggiebaseball]

My wife uses Di2 levers (7970), and already has the shim, but is finding it hard to squeeze the brake, which ends up making your tiny little hands hurt at the end of rides.

I too must admit, that compared to the supple and luscious give of my chorus brake levers, that hers are DARN stiff, it almost feels like one of those hand strengthener toys that wrestlers and freeclimbers use to give them Popeye hands.

IS there some trick like lubing cables, shortening housings, different return spring, etc. that people could suggest?

This is not a question about lever travel- her issue is the actual force required to move that amount of travel.

Thanks!

[Louis]

Can you modify the pre-load on the brake caliper spring? That would change the force seen at the lever. Some calipers (I believe some flavors of Ultegra) allow you to do that.

[bobswire]

Have you adjusted the reach besides shims?
The brake levers have a reach adjustment. Pull the top part of the rubber hood back to expose the reach adjustment screw . Tighten this screw to bring the lever back toward the bar for smaller hands.
BTW I didn't think the Di2 came with shims since you adjust lever reach shown below.
http://i49.tinypic.com/aoak1u.jpg

[reggiebaseball]

Thanks for your replies.

bob
It is not about reducing the reach, it is that the force to squeeze them is too much, way too stiff.

Lou,
I will try to look into that spring tension.

[monkeybanana86]

would this have to do more with the caliper?
I haven't owned shimano in a while but how about disconnect the cable from the caliper and pull on the lever to see if it's one or both

[benc]

7900 calipers too?

[Louis]

http://www.lowestgear.com/e/100812e_87.jpg

I'm not sure this is what your calipers look like, but I believe I've seen some that allow you to use different width "little black thingies" that position the end of the spring. As you look at the pics above, you can see how if you were to move the arm of the spring that is kind of pointing at you to the left, that would increase the pre-load on the spring which would increase the force required at the brake lever. In this instance, since the spring is as far to the right as it's going to go, there is no way to lower the tension. (for this wire, obviously if you used a smaller diameter wire you could lower the spring force, but I don't even know if they offer different K springs).

Good Luck

[reggiebaseball]

actually her calipers are tektro black something or others, but they were not stiff when used with 5700 levers.

I know the new shimano levers have a different pull ratio, but was not sure that this would impact how "hard" the levers feel.

[Louis]

actually her calipers are tektro black something or others, but they were not stiff when used with 5700 levers.

I know the new shimano levers have a different pull ratio, but was not sure that this would impact how "hard" the levers feel.

Are the Shimano lever pull ratios intended to the matched with the calipers, so they give you a "reasonable" hand force? That may be your (her) problem.

[vqdriver]

Before getting too far into this I'd remove the brakes from the frame but still connected to the cable. Try the brakes like this with no bends and see if it's a simple cable drag issue. You may want to undo some bar tape as well to make the housing as straight as possible. If you notice an improvement you just have to minimize drag in the line.

[ultraman6970]

What cable and housing are you using?? I got a similar problem with campagnolo in the read brake time ago, for some reason got harder but not that much to make it a problem. I believe my problem was due to friction because the cable was doing a weird bend and because i did not greased the cable at all in one end....

[oldpotatoe]

actually her calipers are tektro black something or others, but they were not stiff when used with 5700 levers.

I know the new shimano levers have a different pull ratio, but was not sure that this would impact how "hard" the levers feel.

Have her 'try' some 7900 brakes/levers, maybe on a bike shop bike...I'm thinking 7900 calipers, new, well trimmed brake housing, good 'slick' brake cables..long enough housing, will help.

I think the Tektro's are the problem, coupled with the lever pull/shape of the 7900 levers(Di2).

[oldguy00]

You put down the $$ for di2 and then went with the worst quality brake calipers on the planet???
Of course they feel like sh*t.
Seriously, I've owned a couple pair of tektros in the past, they were both terrible, and very stiff.

[oldpotatoe]

You put down the $$ for di2 and then went with the worst quality brake calipers on the planet???
Of course they feel like sh*t.
Seriously, I've owned a couple pair of tektros in the past, they were both terrible, and very stiff.

Yep, I agree. Bet the bike was OE with Di2 and the brilliant 'product manager' decided to save a few $ on really crappy brakes...

[binxnyrwarrsoul]

You put down the $$ for di2 and then went with the worst quality brake calipers on the planet???
Of course they feel like sh*t.
Seriously, I've owned a couple pair of tektros in the past, they were both terrible, and very stiff.

+1. Got a bike with Tekro calipers (not Quartz), were on the block and sold (more like given away) before the bike was even ridden. Even Ultegra level calipers are light years ahead. Search the classifieds here, I think there's a few up for sale (or just post a WTB).

Some sweet 7800 Dura Ace calipers here,
http://forums.thepaceline.net/showthread.php?t=114409&highlight=shimano+brake.
Pic here,
http://www.flickr.com/photos/64959882@N07/7832450798/in/set-72157631179162480

[zandrrr]

Thanks for your replies.

bob
It is not about reducing the reach, it is that the force to squeeze them is too much, way too stiff.


I wonder if Bobswire's point was that if you have shimmed the levers, rather than adjusting the reach via the screw, that perhaps you adjusted all the "easy" portion of the pull out of them. So if the lever has a progressive pull, where it is easier at the beginning and ramps up to being stiffer at the end, and you've shimmed them so they start at the stiffer part of the curve, then removing the shim and adjusting the reach via the screw may solve the problem.

For the record I have no idea how the cable pull on Di2 levers work, but this seems like a plausible explanation to me.

[bobswire]

I wonder if Bobswire's point was that if you have shimmed the levers, rather than adjusting the reach via the screw, that perhaps you adjusted all the "easy" portion of the pull out of them. So if the lever has a progressive pull, where it is easier at the beginning and ramps up to being stiffer at the end, and you've shimmed them so they start at the stiffer part of the curve, then removing the shim and adjusting the reach via the screw may solve the problem.

For the record I have no idea how the cable pull on Di2 levers work, but this seems like a plausible explanation to me.

Zandrrr, Thanks. That was the gist of my thoughts. Mind if I submit my posts to you in the future for editing before I post them? :^)

Also those of you dissing Tektro. I have both 7800 and Tektro Quartz R740 on different bikes and I'd be hard pressed to tell the difference in stopping power as well as lever pull between those two.
Obviously Tekro makes calipers for cheap OEM bikes but their Quartz series are quality calipers.
Having said that, the 7800 are my favorites.

[reggiebaseball]

Yep, I agree. Bet the bike was OE with Di2 and the brilliant 'product manager' decided to save a few $ on really crappy brakes...

Thanks again for all the help! IT is very considerate of forums members to take the time to chime in with suggestions, I really appreciate it.


The bike is an entry level Cannondale Aluminum Synapse that she likes (probably for the color and that is was made in the USA). Cannondale often specs Tektro, especially on 105 level bikes.

I gave her my Di2 setup this year when I went Campy on all my rides, but she asked to keep her black brakes (Again she liked the color). She weighs under 130 lbs and has always found the brakes absolutely fine when running with her 5600 series 105, both in stopping power and in lever feel.


I will investigate a brake swap for her,
I did try some Ultegra Di2 setups in a shop and they were STIFF at the lever too, but I assumed they were brand new and not broken in, while her levers have a thousand miles on them at least (before being migrated to her frame). Likewise her tektro brakes have maybe 3000 miles on them from last season.


I had her stuff professionally installed, I don;t mechanic myself, it was an error for me to say they were shimmed for her, they were reach adjusted using that screw. I will test releasing that screw a bit to see if the sweep was reduced into the hardest portion and if relaxing it a bit allows for more ease.

We are at the point where we bring the bike back to the mechanic for the 300 mile post build checkup and say "tweak this, fix that, etc." and I like to come in armed with has much knowledge as possible so I can say "the brakes are too stiff, please lube the housing, check for kinks, etc."

[ultraman6970]

Forgot to add this, wonder if the back bolt of those calipers is way too tight???

[cmbicycles]

Do the calipers release all the way when you let go of the brake levers, or can you pull them back out to take slack out of the cable? Sometimes if you have new housings put on you can get a burr on the cut end that will cause significant drag. I am ocd about filing my ends square on all my housings.
I also agree with the previous suggestions to check for good housing length and smooth cable pull. You can disconnect the cable and hold it with your fingers while squeezing the brake lever to see if it feels smooth. If it does feel smooth, then its in your calipers. If it isn't smooth then its in the housings/cables or the lever so work your way back up to the lever. Check the housing ends under the ferrules and at the brake levers as well as for kinks in the cable.