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4iiii powermeter collides with rear brake, which alternative brake to buy?

gasmeistergasmeister Posts: 8
edited October 2017 in Road buying advice
Hello,

I own a BMC Timemachine TMR02 Bike with a Shimano 105 BR 5810 direct mount rear brake. Here is a picture:

https://picload.org/view/rwplpada/img_20170827_195313.jpg.html.

I've bought a 4iiii precision powermeter (strain gage at the crank arm) and recognized it collides with the rear brake because ther isn't enough clearance between the brake cable mounting at the caliper and the strain gage. I know that this is a common problem, so I've bought a replacement brake (TRP 925.1R), but this hat the wrong mount (center bolt instead of two bolts). I see two alternatives:

1. I would like to buy the BMC TMR01/TM01/TM02 rear brake, which uses the two unused threads you can see in the picture. Here is a video it works:
https://www.youtube.com/watch?v=C7HlrtcWmow
I already sent an email to BMC, but no answer...my authorized bike dealer also wrote an email, but didn't receive an answer too. The brake arms can be ordered in an online shop (https://www.evanscycles.com/bmc-rear-brake-tm01-tm02-EV158261), but without return springs and mounting bolts and i don't know where to buy these parts.

2. There is the TRP T850 brake:
https://www.trpbrakes.com/category.php?productid=1292&catid=183
But i don't know if this brake has the right mount (my shimano brake has 49mm bolt clearance) and if there is enough space for the brake.

Does somebody may have a good idea what to do now?

Thanks.

Posts

  • timothywtimothyw Posts: 2,482
    Get a different power meter? Is it too late to return the 4iiii?

    Nice excuse to spring for a dual sided power meter instead I'd say.
  • foggymikefoggymike Posts: 862
    I'd return the 4iiii and get a P2M - only £100 more than Stages/4iiii at the moment for an S type Rotor 3d24 set up including more than decent Praxis rings and rotor chainring bolts. Why would you go one sided for that kind of price difference? Hopefully it's not too late.

    These 1 sided pm's need to radically decrease their prices to continue to make sense.
  • Keep brake. Return powermeter.


    :)
  • Sounds like a new bike needed
    I'm sorry you don't believe in miracles
  • phil485phil485 Posts: 348
    I have a similar problem in my Felt AT with stages.

    I am currently running a tri rig omega rear brake which works. Just ordered a new Dura ace rear to see if it has ok clearance.
  • Hello,

    I bought the 4iiii for 384€. Rotor 3D24 with power2max costs 679€. Next cheapest is FSA Powerbox for 499€. I like the solution of just changing the crank arm and the 4iiii has also a cadence sensor included.

    As far as i know, all powermeters work with strain gages and therefore i don't see the big advantages of a double sided powermeter except from the possible left/right inbalance. And it costs much more...

    It's not to late to return the 4iiii, i have 60 days left. If there is a good solution with the brake, i will keep it. If not, i will maybe buy the Rotor.

    @foggymike
    Which configuration of the rotor 3D24 would you exactly buy? I would like to have 52/36 chainrings.

    @Phil485
    The Tririg Omega can't be bought in Germany...The only brake i found is the TRP 850.
  • angry_birdangry_bird Posts: 3,782
    I have a TRP TT brake on the back of my storck so the stages could get clearance. Works fine. Cheaper than replacing the PM.
  • Angry Bird wrote:
    I have a TRP TT brake on the back of my storck so the stages could get clearance. Works fine. Cheaper than replacing the PM.

    Do you mean the TRP TTV? https://www.trpbrakes.com/category.php? ... 2&subcat=0
    I don't know if it fit's into the BMC mounts :?
  • StillGoingStillGoing Posts: 5,207
    gasmeister wrote:
    Hello,

    I bought the 4iiii for 384€. Rotor 3D24 with power2max costs 679€. Next cheapest is FSA Powerbox for 499€. I like the solution of just changing the crank arm and the 4iiii has also a cadence sensor included.

    As far as i know, all powermeters work with strain gages and therefore i don't see the big advantages of a double sided powermeter except from the possible left/right inbalance. And it costs much more...

    It's not to late to return the 4iiii, i have 60 days left. If there is a good solution with the brake, i will keep it. If not, i will maybe buy the Rotor.

    @foggymike
    Which configuration of the rotor 3D24 would you exactly buy? I would like to have 52/36 chainrings.

    @Phil485
    The Tririg Omega can't be bought in Germany...The only brake i found is the TRP 850.

    Rotor 3D24 with Type S from P2M. P2M also has an inbuilt cadence sensor and temperature compensator. Its up to you what size chain rings you specify, just select the BCD you want.
    I ride a bike. Doesn't make me green or a tree hugger. I drive a car too.
  • If you are happy with what you have I'd just replace the chainrings like for like so you can just slot it in. You can get the Praxis rings on the deal in 53/39, 52/36 or 50/34. Being old school (and just old!) I have 53/39 8)

    I swap mine between bikes and it takes about 2 minutes. There are only 2 allen key bolts to deal with, so not much different to swapping a shimano crank arm. No faffing with recalibration or anything, just stick it on and ride.

    You got the 4iiii very cheap, but you do get the rest of the chainset and more accurate measurement for your extra 300 euros. Also when you buy new Shimano cranks or want to swap bikes you'll end up with a non-matchng crank arm with 4iiii/stages. At least with the P2M both sides will always match. Some people aren't bothered by that but I am #biketart!
  • angry_birdangry_bird Posts: 3,782
    gasmeister wrote:
    Angry Bird wrote:
    I have a TRP TT brake on the back of my storck so the stages could get clearance. Works fine. Cheaper than replacing the PM.

    Do you mean the TRP TTV? https://www.trpbrakes.com/category.php? ... 2&subcat=0
    I don't know if it fit's into the BMC mounts :?

    Yep that's the one I believe, fits on the storcks direct mounts fine and does the job.
  • Angry Bird wrote:
    gasmeister wrote:
    Angry Bird wrote:
    I have a TRP TT brake on the back of my storck so the stages could get clearance. Works fine. Cheaper than replacing the PM.

    Do you mean the TRP TTV? https://www.trpbrakes.com/category.php? ... 2&subcat=0
    I don't know if it fit's into the BMC mounts :?

    Yep that's the one I believe, fits on the storcks direct mounts fine and does the job.

    OK but i think this one will not fit into the BMC Frame...Some shops say "A TTV Road arm measures 78mm between the mounting bolt and the cable pinch bolt" but i need > 100 mm to get from the mounting bolts behind the wheel :(

    @foggymike and philthy3

    The FSA Gossamer is 130€ cheaper then the Rotor 3D24...is there any disadvantage except ~100g extra weight?
  • StillGoingStillGoing Posts: 5,207
    Just the weight and Rotor is more solid IMO.
    I ride a bike. Doesn't make me green or a tree hugger. I drive a car too.
  • philbar72philbar72 Posts: 2,228
    the real issue with the TMR02 is the back brake is proprietary. the way I got it to work (on a TMR01 with the same brakes) with my pioneer PM was to run thinner brake pads and the pioneer is dimensionally ( the powermeter module) around the same size as a 4IIII.

    its a bit of a faff to be honest. you won't get pedal strike though!!
  • philbar72 wrote:
    the real issue with the TMR02 is the back brake is proprietary. the way I got it to work (on a TMR01 with the same brakes) with my pioneer PM was to run thinner brake pads and the pioneer is dimensionally ( the powermeter module) around the same size as a 4IIII.

    its a bit of a faff to be honest. you won't get pedal strike though!!

    Hello,

    Today my bicycle dealer got an answer from BMC. The BMC brake can be bought for 135€ so I ordered it. Do you mean that the 4iiii will not fit, even with the BMC brake? I can't believe that, because in the video (https://www.youtube.com/watch?v=C7HlrtcWmow) the brake seems to be completely hidden under the chainstays. Or what do you mean?
  • angry_birdangry_bird Posts: 3,782
    gasmeister wrote:
    Angry Bird wrote:
    gasmeister wrote:
    Angry Bird wrote:
    I have a TRP TT brake on the back of my storck so the stages could get clearance. Works fine. Cheaper than replacing the PM.

    Do you mean the TRP TTV? https://www.trpbrakes.com/category.php? ... 2&subcat=0
    I don't know if it fit's into the BMC mounts :?

    Yep that's the one I believe, fits on the storcks direct mounts fine and does the job.

    OK but i think this one will not fit into the BMC Frame...Some shops say "A TTV Road arm measures 78mm between the mounting bolt and the cable pinch bolt" but i need > 100 mm to get from the mounting bolts behind the wheel :(

    @foggymike and philthy3

    The FSA Gossamer is 130€ cheaper then the Rotor 3D24...is there any disadvantage except ~100g extra weight?

    I've lied to you! Sorry, bad memory (in my defence I can't check the bike as I'm not riding it at the moment and it's in the shop- very long story but they've had to nick the back brake of it to fit to another customer's bike in a hurry and as I'm not riding the Storck at the minute I don't really mind)

    This is what it actually was, IIRC we were going to do the TRP one, and when it arrived didn't work, so we went with this. Forgetful me! To be fair I don't look at it very often.
    http://www.tektro.com/products.php?p=56
  • Hello,

    there was a bit delay in delivery of the brake, but now everything works fine. Here is a picture:
    https://picload.org/view/dgliiooa/img_20171003_120739.jpg.html
    Power readings look good to me and the BMC brake has also a much better performance than the 105 brake, so I am satisfied :D
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