bluehills3149

I got some Sensah 9spd shifters (about $50 delivered) to convert a Centurion Ironman from the original 6spd Shimano 105 to 2x9spd. The shifting works great using the original derailleurs although note I also replaced wheels, chain, cassette (12-28) and front chainring from 42 to 39 teeth.
But the braking is woeful. The front caliper is a newer dual-pivot shimano but the rear is the old 105 single pivot. The front brake is kinda OK but you need a fair amount of hand pressure but the rear is terrible no matter how hard you pull the levers.
Unfortunately there is scant info about these levers online regarding how to install or what derailleurs and/or brake calipers they are compatible with ( the rear derailleurs are compatible with old Shimano 6-10 speed and not the 11spd or Tiagra 4700 series).

Shimano changed the cable pull on their brakes when they went to the 5800/6800/9000 series and called it SLR-EV and it uses a variable pull ratio and the measured pivot point is about 36mm in radius. The old brake standard is confusing called "new Super SLR" and was used on the older brake levers (and is still used today on Sora and Tiagra).
More info about brake pull is here:
https://www.bikeforums.net/bicycle-mechanics/1041221-definitive-but-wildly-inaccurate-guide-brake-cable-pull-ratios.html

The question is what are the Sensahs? Some ads imply they are Sora/Tiagra compatible but I measured the radius pivot point and it's about 35mm (but not variable like Shimano) which implies kinda SLR-EV compatible. The old Shimano levers (and Sora) are about 18-20mm so these are definitely different and the terrible performance backs this up.

rosefarts

Before even looking at the levers, I have a few questions.

1. How did the bike stop with the old levers?

I have similarly aged Dura Ace calipers with the original levers and it really doesn't work well. It's more of a garage queen than rider though, so it's ok. My wife has a similarly aged Ironman with 105 and it stops as well as any modern non disc bike out there. So the question is, did the levers make the performance worse or was it kinda bad to start with.

Before I even considered the lever leverage I would look at routing. How smooth does the cable move inside the housing. Are there any bends or kinks. Does the housing move around inside the cable stops when you pull the lever.

Are the brake pads from 1986?

Are the rims clean?

Andrew R Stewart 

I just measured an old 5500 Shimano lever for it's pivot to cable end shaft, about 19mm. That's a HUGE change of leverage. The single pivot rear caliper just further reduces mechanical leverage. I'll bet the current set up has really firm lever feel, like a rock hard pad clamping rim point. That's the trade off, A hard/stiff lever feel with little actual leverage or a softer/flexy lever feel but with greater leverage.

I suspect the levers were designed with the current crop of calipers that have increased their leverage factor. Andy


Additional and not asked for info- I use Campy Ergo levers from the mid 1990s on my bikes with dual pivot calipers of about the same of slightly later era. They have plenty of leverage for my needs including when I had Campy long reach calipers on my commuter and the cantis on my touring bike. The pointy hooded Campy levers measure at about 20mm BTW.

2cam16

If you haven't already check the Trace Velo channel on YouTube. He has Sensahs on his bike.

bluehills3149

So I changed the front (dual pivot) pads to some cool-stop ones and set the pads to be further from the rims so you need to pull the lever a bit before the brakes engage and the barking is now acceptable but not as good as the original old levers (and regards the cables - they were all new and the pads too).
I think Andy is correct - they chose the latest long-pull ratio to suit the newer style calipers. My guess is that since these levers are available in multiple models in 7speed right up to 12 (yes 12!) speed so rather than make 2 production models they just made a single model that utilizes the newer cable pull (SLR-EV) and for those with older brakes you just have to pull harder.
My recommendation is to use good dual-pivot calipers, good cables, good pads like cool-stop or shimano and back off the pads a bit from the rim.

williamskg6

I recently built up a Specialized Sirrus from 1987 using Sensah Empire shifters (11 speed) for SRAM. I am using Tektro R741 brakes. While they work OK, they aren't awe inspiring. Front braking seems mostly acceptable when riding on the hoods but not as reassuring as when riding in the drops. I wonder sometimes if I was riding on the hoods and had to stop really, really fast if I could do so. The rear brake is pretty weak no matter what, and I know that's partly due to the much longer cable and housing. I have not replaced the pads yet, but I did use brand new Jagwire cables and housing. I do plan on switching to some better brake pads to see if I can increase my confidence in the brakes.

bluehills3149

Update. The Chinese shifters from Sensah and almost certainly LTWOO utilize the long-pull SLR-EV cable design on all their shifters, from 7 spd right up to 12 spd. Brake calipers from Shimano that use long pull are the current 105, Ultegra and Durace but these cost ~$100 up so it kind of kills the budget upgrade idea.
These calipers can be identified by having 2 pivot points separate from the attaching bolt rather than 1 pivot and the second pivot is the retaining bolt design of traditional "dual-pivot" brakes. Searching for other brands that utilize this design I found 2 Chinese brands from ZRace BR-001 and ZTTO available for about $25 a pair - considerably less than the ~$100 for 105. How do these calipers compare to Shimano? No idea, but some reviews (and there are not many) say the quality is great but they work OK. Of the 2 brands my pick is the ZRace with replaceable pads rather than the integrated pads of the ZTTO's.

These are traditional dual-pivot and note the pivot and the second pivot is the retaining bolt.


This is new Shimano 105 and note the 2 pivot points separate to the retaining bolt



This is a Chinese ZRace and note it also has 2 separate pivots.

captain_inch

Interesting topic, i am about to restore an old steel race bike as a comuter, and the Sensah SRX Pro seems to be the only 1 by chinese groupset available for road shifters.

@bluehills3149, did you end up buying a Zrace of ZTTO caliper to try it out ? I'm considering doing so, and would appreciate a feedback on what to expect.

bluehills3149

No- I haven't tried the other calipers as I used a set of standard Shimano dual-pivots (BR-R560) and they work sufficiently.

captain_inch

Alright. As advised on this thread, I am about to order some Sram Force caliper. They should work fine, do you confirm?

bluehills3149

They should work OK but if I were buying new and money was not important (but then why get Sensah shifters?) , I would get the ideal match which is Shimano 105 but that will probably be a bad deal financially as they probably exceed the cost of the shifters. So unless you have a set of SRAM calipers available for free/low cost I would get the Zrace at ~$25 /pair and spend the savings on decent pads like Cool-stops.

icemilkcoffee 

Why didn't you go with the more tried-and-true Microshift brifters?
BTW I have your twin:

I put a 7 speed freewheel on the original wheel, and changed the shifters to Sora 3300 2X7 brifters. I'm using 105 1055 dual pivot brakes and it stops very well.

captain_inch

Thanks for the feedback, appreciated. I was thinking about buying the Zrace, but I am restoring an old bike and would like to have chromed components in order to have a nice look. The new shimanos are out of price range for me. And the only brakes I could find are the Sram ones. I can get a pair of Sram force for 55€ (65USD), which makes it ok for me. I've used the Red calipers and they were great.

Nice rig. And good point / question. Don't really know why but I'm not super inclined to go for such a brand. But the 11s of the Sensah vs 10s of Microshift's is definitely a plus when considering a single chainring setup. I would just appreciate that there would be more 1 by groupsets in entry-level price range.

systemBuilder

I would not bother getting the ZRace BR-001 brake shaped-objects (BSO's). They are terrible. The pads are really poor quality and require replacement. And apparently the cable stop uses a BASO (Barrel-Adjuster-Shaped Object) which actually DOES NOT TURN. The ZRace-BR001 truly are garbage brakes. Just get something cheap from Tektro (like a R3xx model or R5xx model) and you'll be much much happier !!

Kontact 

Shimano lists their latest calipers as essentially compatible with the older stuff. Are we sure that the Sensah levers aren't intended for mechanical disc?

maddog34

the pull radius is similar to V-brake and MTB disc.

Mackers

Hmmm, I have a set of those ZRaces and while the stock pads weren't great the barrel adjusters work just fine.
They worked well with Sensah 11S levers.