Recreational Cyclocross and Gravelbiking - Modifying Shimano CX-50 Brakes
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10-14-11, 12:37 PM
I'm looking to modify either a Shimano CX-50 or CX-70 brake. I haven't had a chance to look at one of these in person yet, so I don't know if it will work.
What I want to do is either replace or shorten the spacer between the pad and the brake ( see attached pic ). I don't know how that spacer is kept in place. Does the screw screw into that, the pad or does the pad have a pole that goes the the brake arm. Could I use a shorter screw once the spacer is replaced? Is it needed? Does it come with different size spacers?
If anyone has any advice or pictures of this assembly, I would appreciate it.
Or, is there anything proprietary about the brake that would prevent me from using the shoes from another brake, like the R550 without the CX-50/70 spacer?
10-14-11, 12:51 PM
I am not sure how it attached (probably just a hollow spacer) but I think much of the design intention of these brakes with the long spacer was to provide good clearance for mud buildup. A shorter spacer will negate that advantage and you would also need to shorten the saddle cable to maintain the mechanical advantage. The saddle cable that these come with is non-adjustable so you would pretty much need to get a different saddle cable (or else find a shorter cable for the left side and trim the housing on the right side). If you dont want the mud clearance that these offer, there are many other (non-shimano) brake offerings that would likely be better choice.
10-14-11, 12:56 PM
No worry about setting up the proper mechanical advantage. I understand why they did it, but this is not for a cyclocross bike. It is for my older Miyata touring bike. The posts on mid 80's forks are closer than today's standard, so newer cantilevers won't fit. But, with this design and a shorter spacer, I think I can get it to work. I posted here, because I thought there would be a better chance that a cyclocrosser (is that correct?) would know about these brakes.
The new Shimano brakes come with three sizes of spacers and three corresponding length screws. The Shimano installation instructions (http://techdocs.shimano.com/media/techdocs/content/cycle/SI/Cyclocross/SI_8K50A/SI-8K50A-001-Eng_v1_m56577569830749996.pdf) even have a handy chart that is supposed to help you pick the right size based on your post spacing and rim width.
Also, parts diagram: http://techdocs.shimano.com/media/techdocs/content/cycle/EV/bikecomponents/BR/EV-BR-CX50-3222_v1_m56577569830767904.pdf
10-14-11, 02:05 PM
Thanks for the link Andy_K. I don't know why I didn't think about checking Shimano's PDF, I guess just stupidity on my part. Especially since I have often gone to their site to look at their documents. Though the chart does not list my dimensions, the post width is the shortest on the list, but my touring rims are 2mm wider than the rims they mention. But looking at the pdf, it looks like I will be able to use a spacer or file down their shortest one and either use a shorter screw or add a spacer on the other side.
Edit: After looking at the parts diagram, it looks like the spacer is concave on one side, so I will need to file down the other side instead of using a different spacer.
This brings me great joy and happiness.
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