Re: Conversion report: 1991 Miyata 914

[Jon Doyle]

Nice conversion!

I think your front brake cable is just a bit too long. It seems likely that an extra ~1cm combined with a 90º bend could generate some friction (mushy). I've had similar experiences, and shortening the housing fixed it. The Park Tool website has fine article on cables and how long to make them,

Jon

On Tuesday, December 11, 2012 4:03:54 PM UTC-5, Seokho Jeong wrote:

I used a pair of in-line barrel adjusters and a v-brake noodle when I was installing brake cables. The front brake sort of works and it actually stops me but... it feels really mushy and the lever bottoms out before I could lift the rear wheel. I am trying to figure out if that's because the straddle wire is too short or that's because of my lousy cabling...

[William Lindsay]

If my eye is correct, those are Shimano Sante brakelevers.  If memory serves (I was working at a shop through the late 80s through the early 90s), those levers pulled very little cable.  They were squishy with everything, in my experience.  If the feel of the brakes or your safety on the bike are unacceptable, I'd recommend that you consider replacing your brakelevers with ones that pull more cable.  I am certain that the community on this group could list brakelevers that they have used with Mafac Racers.  

On Tuesday, December 11, 2012 1:03:54 PM UTC-8, Seokho Jeong wrote:

I converted my 1991 Miyata 914.

Originally it had really tight clearance with 23mm tire and it looked like 25mm will be the widest I can go with.

Laced a pair of synergy rims (o/c for rear) to a pair of ultegra 6500 hubset using wheelsmith 14g straight spokes and installed col de la vie's.

I went with a pair of mafac racer's my friend gave me.

Actual measurement of Col de la vie's on my rims is 35mm or so. and the clearance on the chainstays is like 2mm on each side.

I used a pair of in-line barrel adjusters and a v-brake noodle when I was installing brake cables. The front brake sort of works and it actually stops me but... it feels really mushy and the lever bottoms out before I could lift the rear wheel. I am trying to figure out if that's because the straddle wire is too short or that's because of my lousy cabling...

<a href="http://s869.beta.photobucket.com/user/sokito/media/650b_miyata914/20121211_134513.jpg.html" target="_blank"><img src="http://i869.photobucket.com/albums/ab253/sokito/650b_miyata914/20121211_134513.jpg" border="0" alt="Photobucket"/></a>

<a href="http://s869.beta.photobucket.com/user/sokito/media/650b_miyata914/20121211_134532.jpg.html" target="_blank"><img src="http://i869.photobucket.com/albums/ab253/sokito/650b_miyata914/20121211_134532.jpg" border="0" alt="Photobucket"/></a>

<a href="http://s869.beta.photobucket.com/user/sokito/media/650b_miyata914/20121211_134555.jpg.html" target="_blank"><img src="http://i869.photobucket.com/albums/ab253/sokito/650b_miyata914/20121211_134555.jpg" border="0" alt="Photobucket"/></a>

[Seokho Jeong]

they are early version of shimano 600 aero levers (6208?) but i guess those might have similar issues as you described...

another thing might be that I installed the levers slightly too low, so that they hit the handlebar earlier than they supposed to?

i have shimano 600 non-aero levers (6200 series) you think they will work better than the aero levers?

[Seokho Jeong]

I sort of re-did the housing for the front brake last night. the rigid 90 degree v-brake noodle didn't seat properly on the cable hanger so I cut 1cm at the end of it and now it seats perfect. I also meticulously filed each end of housing pieces. i bent the lower arm so that i have proper amount of toe-in. I tried adjusting straddle wire length with no success. I thought, in my application, rather than the length of housing itself, too many joint in the housing might be the problem? It's like housing-barrel adjuster-housing-noodle, so instead of having two housing ends now it has 5 housing ends including the noodle.

or it might be simply the pads problem?

worse, the brake sqeals now. it didn't before....

[William Lindsay]

I think your non-aero levers may work better.  As my scientist friends tell me "that's an empirical question".  I'd recommend you measure.  Measure how many millimeters of cable gets pulled with "one handful" of lever travel.  If your alternate levers pull more cable, give them a try.  Just judging from my eye, the Mafac levers that went with those brakes look to me that they would pull a lot of cable.  

[Jim G]

Noe also that MAFAC Racers are pretty squishy, flexible brakes --
especially if you're used to Shimano dual-pivot sidepulls and the
like. Running the brake pads at the bottom of the slot exacerbates
this issue. That said, they work really well and offer great
modulation! It looks you're using generic, black brake shoes. Try
swapping those out with some salmon Koolstops or similar.

-Jim G


William Lindsay wrote:
> I *think* your non-aero levers may work better. As my scientist friends

[Seokho Jeong]

I cleaned the rim braking surface and pads with degreaser, readjusted pads, and moved lever up a little bit. Now it squeals but performance got noticeably better and I actually lift the back wheel easily now. Might be that new rims were slightly oilly? It never squealed before I cleaned the rim and the performance was barely acceptable. but now it works really well.

[Ken Freeman]

You altered the rim surface and the brake lever position at the same time.  Not sure the lever change was highly significant because I don't know those levers, but if it could have been then there's no way it say it was leverage or it was cleaning that made your braking improve.

On Wed, Dec 12, 2012 at 9:58 PM, Seokho Jeong <luke...@gmail.com> wrote:

I cleaned the rim braking surface and pads with degreaser, readjusted pads, and moved lever up a little bit. Now it squeals but performance got noticeably better and I actually lift the back wheel easily now. Might be that new rims were slightly oilly? It never squealed before I cleaned the rim and the performance was barely acceptable. but now it works really well.

--
You received this message because you are subscribed to the Google Groups "650b" group.

To view this discussion on the web visit https://groups.google.com/d/msg/650b/-/2OiSsB6Vo0MJ.

To post to this group, send email to 65...@googlegroups.com.
To unsubscribe from this group, send email to 650b+uns...@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/650b?hl=en.

--
Ken Freeman
Ann Arbor, MI USA

[Brad]

The noodle on the front looks contorted.  I would take out the inline barrel adjuster for the front and put the barrel adjuster on the cable hanger at the headset instead.    The best aero levers with Mafac's are the new DiaCompe ones- (or the Tektro equivalent).  They have a built in quick release mechanism that with decoupling the straddle wire lets you open the brakes up completely.

Here is my rig as a comparison point (my brake cabling from the opposite side is idiosyncratic because I like it that way).
http://www.flickr.com/photos/8040919@N06/5644229031/

http://www.flickr.com/photos/8040919@N06/5644794512/in/photostream/

[Dave]

I think your diagnosis of having too much stuff on there is correct. Noodles aren't great - they work with V-brakes but keep in mind they are pulling a lot more cable than a road lever/road brake, so there is more "margin for error" (for lack of a better term) in the system. Plus they can really suck the road grime in there without letting it out. I have no experience with in line adjusters other than I've failed to understand why someone wants them on a brake cable - indexed shifting near the cockpit I can kind of understand, but if you're adjusting things that much while riding you may prefer to spend just a bit more time on the bike when it's in the stand. I put TRP straddle cables with adjustable stops on my CX bike this year thinking that would be really handy and I have yet to use them.

My recommendation would be to install just housing - no noodle, no adjuster. If you really want the fine tune feature perhaps the TRPs would work? http://www.probikekit.com/us/trp-straddle-cable-adjuster-for-eurox-cantilever-brakes.html?utm_source=google&utm_medium=base&utm_campaign=google_base_usd&gclid=CJjm2u-cmrQCFQtxQgodHF0AlQ  Not too much hands on experience with the Mafacs and I'm not sure if the diameter of the little cable stop dealie (my vocabulary is in fine form this AM) would fit. 

Regardless, experiment with the straddle cable height as well - higher or lower depending on the riding you do and your preference. And as the above poster pointed out - it's not a late model shimano short reach dual pivot. It's not going to feel as crisp.

Conversion looks good! I used to sell those Miyatas in 1991 - great bikes with 700c, can only imagine the improvement w/ 650. I keep my eye open for that exact bike (although I preferred the blue).

[Brad]

I question whether the TRP's would work with Mafac Racers.  The original setup had the adjusters in the lever, but the levers were pre aero.  An adjuster allows one to lock the brake pads against the rim with the adjuster dialed out, set the anchor, and then dial the adjuster in ( down) to create the optimum distance from the rim.   Doing that with the pads on Mafacs is a recipe to a very long day, or week, or month.  Old school barrel adjusters don't take up a huge amount of space.  The Weinmann/ Diacompe steel cable hangers provide a good amount of drop.  Like this one.
 http://i.ebayimg.com/t/NOS-Vintage-Weinmann-Front-Brake-Cable-Hanger-w-Barrel-Adj-/00/s/NzY4WDEwMjQ=/$%28KGrHqVHJB8E7yuqUr0GBPBRgFOTbg~~60_35.JPG

There was a time when using Weinmann's quick release cable hangers with Mafacs was considered pretty cool, but the ability to do the same thing at the lever is even cooler.