Author Topic: Trek 520 poor brakes  (Read 2333 times)

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Offline Pat Lamb

Re: Trek 520 poor brakes
« Reply #15 on: November 13, 2013, 10:46:57 pm »
Petejack, changing the levers doesn't make any sense.  Cables and housing wear out in the normal course of riding a bike; so does handlebar tape.  Unless the levers start to rust, they'll last approximately forever.

You're going to have to replace the tape when you replace the housing.  I'll usually replace cables and housing every 5,000-10,000 miles.  It's nice to get some fresh tape about then, as well, and all three are down-in-the-noise cheap.  Don't think the cables and housing need replacement?  Don't want to take everything apart to check for fraying or cracking?  Want to bet $20 against your life that the cables didn't fray in the last year when there's a stop sign at the bottom of a long, steep hill?

Go ahead.  Replace the cables and housing.  It'll almost certainly improve your braking.  Then splurge for another $10-15 and put on new bar tape as a treat for a job well done.

Offline mbattisti

Re: Trek 520 poor brakes
« Reply #16 on: November 13, 2013, 11:32:43 pm »
Thanks everybody for your suggestions. The levers are the ones that came with the bike along with the SD-5 Vee brakes. The Ultimate does give better braking but is still not fantastic e.g. on an unloaded bike I couldn't launch myself over the bars if I tried. I'm using the Avid pads that came with the brake.
Quote
When you're applying the brakes, how far will the brake levers continue to move after the pads initially contact the wheel rim?
You may be on to something there. They do feel kind of squishy after the pad hits the rim, in fact it's hard to tell when the pads have hit the rim. With my Roubaix cantis there's a definite stop in lever movement when the pads meet the rim. Presumably I should be getting the same with the Trek's V brake? Perhaps after 40,000 miles the levers and outer cables are worn out. Recommendations for cables and levers please?

I don't think it's rim wear. The wheel has only 5k on it and the braking was pretty poor when the wheel was new with new pads.
sounds like the levers are not able to pull enough cable to make the brakes effective. I too would suggest Travel agents

Offline PeteJack

Re: Trek 520 poor brakes
« Reply #17 on: November 14, 2013, 02:21:53 am »
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Want to bet $20 against your life that the cables didn't fray in the last year when there's a stop sign at the bottom of a long, steep hill?
Nothing is frayed, the cable inner is brand new as is the V brake itself. As I said, it is a bit better than the old one but nothing to write home about. I get the point that the levers shouldn't wear out but I'm at a loss as to what else it could be. I'll try a new outer cable and see what that does. I don't much care about the tape. If need be I'll ride without it until I get the brakes right.

Offline DaveB

Re: Trek 520 poor brakes
« Reply #18 on: November 15, 2013, 12:24:56 pm »
.....sounds like the levers are not able to pull enough cable to make the brakes effective. I too would suggest Travel agents
First the bike came with V-brakes (Avid SD5) and matching long pull levers. There are no longer pull levers and a Travel Agent will only make the leverage worse, not better.  Either the OP has the pads set too far from the rims at rest or the brake arm are too flexible or the pads are inferior. 

Offline paddleboy17

Re: Trek 520 poor brakes
« Reply #19 on: November 15, 2013, 12:50:02 pm »
.....sounds like the levers are not able to pull enough cable to make the brakes effective. I too would suggest Travel agents
First the bike came with V-brakes (Avid SD5) and matching long pull levers. There are no longer pull levers and a Travel Agent will only make the leverage worse, not better.  Either the OP has the pads set too far from the rims at rest or the brake arm are too flexible or the pads are inferior.

Which brings us back to the condition of the wheel.  I asked earlier if the wheel was true or not.  If the brakes are loosened to accommodate a wheel that wobbles, they won't stop all that well.  DaveB's implied question about the brakes being properly adjusted is fair game too.  Even side pull brakes generally work.  Cantilever or linear pull brakes should be fine for this application.  Yes, a loaded bike takes longer to stop.

And again, there are hydraulic rim brakes for those that want'em.  I checked, SRAM still makes them, looks like ~$600.

Pad are the cheapest change to make.  Dir the OP try that?
Danno

Offline PeteJack

Re: Trek 520 poor brakes
« Reply #20 on: November 15, 2013, 05:18:58 pm »
Quote from:  Paddleboy
DaveB's implied question about the brakes being properly adjusted is fair game too

Thanks. This seems to have solved the problem. I was unaware how much difference clearance made, I thought that larger clearance just meant that the lever traveled further before braking and that when the pads arrived at the rim everything would be hunky dory. I've now reduced the clearance on the front brake to as small as possible using the adjuster on the cable and the difference in the feel is amazing. Interestingly I can't get the same improvement on the back brake, an original SD-5. It still feels mushy presumably because the SD-5 arms are die castings that flex while the Ultimate's are machined from solid, also the Ultimate has bearings at the pivots which I guess have less play.

I'm going to try new levers anyway, Tektro RL-520s,  in the hope they will have better ergonomics than the originals

<Edit. Corrected name of brakes>
« Last Edit: November 28, 2013, 06:45:42 pm by PeteJack »

Offline Old Guy New Hobby

Re: Trek 520 poor brakes
« Reply #21 on: November 18, 2013, 10:57:10 am »
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If the brakes are loosened to accommodate a wheel that wobbles, they won't stop all that well.

Thanks. I never knew that. (Until now.)