··· - Why is the reach of my caliper too short???

[Pierre]

Hey gang, just building up my new Look 675. I've installed the rear brake caliper and I'm stumped...the damned reach is just a sliver too short. What the heck?

No comments on the choice of sliver rim - it's temporary! Did Look screw up when the drilled the hole through the frame???

http://i1318.photobucket.com/albums/t644/pierre_mcalpine/8198C39B-7D49-4318-B6A9-6D486916C1AD_zpsrrreciu1.jpg

http://i1318.photobucket.com/albums/t644/pierre_mcalpine/4A40C2F1-2B7C-4BC0-8304-0F8C0D243E61_zpsxdiu2m96.jpg

http://i1318.photobucket.com/albums/t644/pierre_mcalpine/8C5F28E0-0805-4732-93D6-6747581C2C5E_zpsqtgcnmk9.jpg

[druptight]

Are you 100% sure that the rear wheel is fully seated in the dropouts?

Looks like you've got an awful lot of tire clearance back there.

Looks like the pictures I find online show it reaching with a standard Ultegra brake (with the pads all the way down in their slots):

http://road.cc/sites/default/files/styles/main_width/public/images/Eurobike%202012%20-%20Look%20675%20first%20ride/Look%20675%20-%20rear%20brake.jpg?itok=HSHrFA-t

[bicycletricycle]

if you have a spacer between the caliper and the frame you can take it out and gain a smidge of effective reach.

also, you can get a round file and extend the slots a little, I have done this before with success, not sure what the maximum amount you can remove while still being safe is, you'll have to use your best judgement.

re check that the wheel is seated correctly, also, double check it with the wheels you are planing to run, rim width can effect this and rims can vary in outside diameter some.

[Pelican]

I have this same issue on my Masi. It's my beater/coffee bike so I haven't bothered to fix it, but I understand your pain!

[bicycletricycle]

Also, these

http://www.bdopcycling.com/BDop%20Offset%20Holders.asp

[druptight]

Biketrike's ideas might all help - but if I'm you and I spent whatever it costs to get my hands on one of those frames, I'm getting in touch with Look - assuming you bought this directly from a dealer and not 2nd hand, long before I'm touching anything with a file or adding drop to my brake calipers.

[stien]

Well the question should not be how to fix it, but why this happened? It's not like this a vintage frame that was originally designed for 27" wheels or something. Send it back!

[distanc3]

How does your front brake clearance look?

[jds108]

Until Pierre confirms that the hub is seated fully in the dropout, I'd assume that's the root cause here...

[lonoeightysix]

assuming the wheel if properly seated, equivalent of stacked tolerances.

pad adjustment in caliper design+distance from brake mounting bolt to dropout+axle to rim brake track distance. you could substitute a part, or modify any of the three areas noted.

had the same problem with an alpha q fork.

[pinoymamba]

whoa that's pretty crazy. what everyone said above is great advice.

i have the opposite problem with my moots and campagnolo brakes... :mad:

[Pierre]

Great suggestions! I have in fact confirmed that the wheel is seated properly. The frame is brand new purchased from a local shop and I have considered bringing it by just to get their advice. I fiddled with the pads some more and I get them ALMOST correctly seated i.e. within a mm so I think I can live with that. I'll be honest, my first thought (after thinking that I should bring the frame back to confirm all is good) was to file the bottom edge of the caliper to give me the extra mm or two. However, I'm now looking more closely at the silver notched washer which sits on the brake caliper axle (as per one of the suggestions) and I'm wondering what purpose it really serves (the one that butts up against the frame itself). If I take that out as suggested, I think I will gain more than enough height to accommodate he brake...hmmm.

[jmal]

This would not happen with disc brakes.:)

[tuscanyswe]

This would not happen with disc brakes.:)

Nope then the wheel would not even fit in the frame if the brake setup was not aligned to standard .)

[Peter P.]

This Shimano Tech Doc (http://productinfo.shimano.com/#/spec/2.4/ROAD/Brake%20%28Caliper%20Brake%29) shows certain Dura Ace calipers have a maximum reach of 49mm. It also shows certain Ultegra calipers have a maximum reach of 51mm. I don't know about Campy or SRAM; you'll have to look those up.

Either the frame was constructed wrong or constructed for a particular caliper.

Yeah; you'd like to think there'd be some uniformity in this spec but I guess not.

I do not know whether you can mix Dura Ace levers and Ultegra calipers if you choose to go that route; they may have different mechanical advantages so be aware before you try.

[Pierre]

and the winners are...lonoeightsix and bicycletricycle!!! When I took the caliper off and removed the silver notched spacer it was clear that I could not do without that as it is notched on both sides and the piece on the caliper that it mates with is not (I thought it was). Buuut, I did have a second bike with some DA7800 on it and the silver spacer on that frame was about half the width of the one on the Look. Switching them has totally addressed the issue. Thanks fellas! Go figure, the difference in width between those two spacers really wasn't much but it did the trick.

[everbeek]

It's the rear brake which I rarely use except in emergencies 2-3 times per 5,000 miles. Take a knife, box cutter or chisel and chamfer the edge. You will lose a few percent of ultimate stopping power but it is essentially unimportant. I am assuming there is nothing inherently wrong with the bike and bridge placement.
-Mike

[Ken Robb]

Maybe someone smarter than me can tell us if DA calipers came with two size washer/spacers to accommodate various frames/forks?

[lonoeightysix]

just for information's sake, the problem i had also involved a mavic rim (basically for a 700c rim, the brake track diameter was too "small"). the brake pad wanted to run into the tire wall unless adjustment was perfect.

[bicycletricycle]

Also, in my experience you don't really need a toothed washer.

[Peter P.]

Maybe someone smarter than me can tell us if DA calipers came with two size washer/spacers to accommodate various frames/forks?

The Shimano tech doc shows only 1 size washer.

Scroll down and download (http://si.shimano.com/#categories/130) the doc.

[oldpotatoe]

Nope then the wheel would not even fit in the frame if the brake setup was not aligned to standard .)

Which standard??:rolleyes:Disc brake standards rival BB and headset 'standards'..

[oldpotatoe]

It's the rear brake which I rarely use except in emergencies 2-3 times per 5,000 miles. Take a knife, box cutter or chisel and chamfer the edge. You will lose a few percent of ultimate stopping power but it is essentially unimportant. I am assuming there is nothing inherently wrong with the bike and bridge placement.
-Mike

:oeeek..2-3 times? Why give up 30-40% of you braking ability?

I wouldn't assume that at all. These frames are designed for short reach brakes and after installing the DA caliper, and using a standard 700c wheel, something in there heightof the brake bridge is amiss if the brake blocks won't reach the rim at the bottom of the slot.