Tektro cr520's on a galaxy

For discussions about bikes and equipment.
User avatar
531colin
Posts: 12572
Joined: 4 Dec 2009, 6:56pm
Location: North Yorkshire

Re: Tektro cr520's on a galaxy

Postby 531colin » 4 Nov 2010, 9:50pm

Meic
These http://www.spacycles.co.uk/products.php?plid=m2b0s105p1716 fit on the top tube cable stop, and will often "make do" for the front hanger, although there are "in line" adjusters that will work for brakes, fitting in the outer cable.

User avatar
meic
Posts: 19355
Joined: 1 Feb 2007, 9:37pm
Location: Caerfyrddin (Carmarthen)

Re: Tektro cr520's on a galaxy

Postby meic » 4 Nov 2010, 11:50pm

Thanks, I already had them planned in my next order to Spa. However this is the only one of my bikes that even has top tube cable stops, I dont know what I would do with the other bikes.
Yma o Hyd

snibgo
Posts: 4604
Joined: 29 Jun 2010, 4:45am

Re: Tektro cr520's on a galaxy

Postby snibgo » 5 Nov 2010, 3:12am

hugs wrote:The low profile canti brakes re CRC are a waste of time on touring bikes unless you ride flat bars & mountain bike levers.

This is because road levers do not have enough cable pull for their operation hence why you need the old style non low profile version or do what a couple of my friends have done and take the canti bosses off completely and use the newer dual pivot action side pulls.

My low profile cantis have worked fine for 20 years on my tourer. True, the new brake blocks have started squealing at the front, but I suspect I can sort that.

User avatar
531colin
Posts: 12572
Joined: 4 Dec 2009, 6:56pm
Location: North Yorkshire

Re: Tektro cr520's on a galaxy

Postby 531colin » 5 Nov 2010, 7:46am

meic wrote:Thanks, I already had them planned in my next order to Spa. However this is the only one of my bikes that even has top tube cable stops, I dont know what I would do with the other bikes.


The brake outer has to stop somewhere?
If you have a braze on cable hanger above the back brake, one of those Mickey things should be OK there, but if the hanger comes off the seat pin pinch bolt, there may not be room for Mickey and to get your fingers in to adjust it.
You can usually find room for an in-line adjuster somewhere (one thats good for brakes, some are only recommended for gears) but not where the outer has to flex to steer, thats asking for trouble, I think.

User avatar
531colin
Posts: 12572
Joined: 4 Dec 2009, 6:56pm
Location: North Yorkshire

Re: Tektro cr520's on a galaxy

Postby 531colin » 5 Nov 2010, 8:05am

snibgo wrote:
hugs wrote:The low profile canti brakes re CRC are a waste of time on touring bikes unless you ride flat bars & mountain bike levers.

This is because road levers do not have enough cable pull for their operation hence why you need the old style non low profile version or do what a couple of my friends have done and take the canti bosses off completely and use the newer dual pivot action side pulls.

My low profile cantis have worked fine for 20 years on my tourer. True, the new brake blocks have started squealing at the front, but I suspect I can sort that.



The snag with low profile cantis is that a lot of the mechanical advantage (MA) comes from Sheldons straddle wire trick. These brakes are therefore extra sensitive to straddle height. As the blocks wear and the straddle goes up, the MA reduces. Straight bar levers not only pull more cable, Shimano tweaked them so their MA increases as they approach the bars, to offset the reducing MA of the low pro cantis.
I can get them to work with drop levers, but this can involve adjusting the brakes twice during a wet day's rough stuff to compensate for brake block wear, so I prefer to use something else, ideally Shimano's parallel push Vbrakes, also no longer made.

snibgo
Posts: 4604
Joined: 29 Jun 2010, 4:45am

Re: Tektro cr520's on a galaxy

Postby snibgo » 5 Nov 2010, 8:37am

531colin wrote:... but this can involve adjusting the brakes twice during a wet day's rough stuff to compensate for brake block wear ...

My blocks don't wear this much in a single day. Do you mean they weren't adjusted correctly, so needed correcting, twice?

Yes, the MA reduces as the pads wear and I adjust the cable. This reduction doesn't trouble me.

To compensate for wear when I have adjusted the cable a fair bit, I de-adjust the cable, slacken the block bolts slightly (only slightly), slide the blocks in, and tighten the bolts.

These brakes are fairly primitive and awkward to setup as they have a single bolt to adjust height, depth and both angles. I tweak them maybe once a year and have never replaced the cables, so it's not a big issue for me.

User avatar
531colin
Posts: 12572
Joined: 4 Dec 2009, 6:56pm
Location: North Yorkshire

Re: Tektro cr520's on a galaxy

Postby 531colin » 5 Nov 2010, 8:53am

snibgo wrote:
531colin wrote:... but this can involve adjusting the brakes twice during a wet day's rough stuff to compensate for brake block wear ...

My blocks don't wear this much in a single day. Do you mean they weren't adjusted correctly, so needed correcting, twice?
.


No, I mean that a couple of hours riding in the Dales including steep descents with the rims covered in a mixture of peat mud and grit can grind a lot off your brake blocks! Rims dont last too well, either!

snibgo
Posts: 4604
Joined: 29 Jun 2010, 4:45am

Re: Tektro cr520's on a galaxy

Postby snibgo » 5 Nov 2010, 9:04am

Yikes, fair enough. For those conditions, I'd want much better brakes than I currently have.

User avatar
CREPELLO
Posts: 5558
Joined: 29 Nov 2008, 12:55am

Re: Tektro cr520's on a galaxy

Postby CREPELLO » 5 Nov 2010, 9:38am

531colin wrote:
snibgo wrote:
hugs wrote:The low profile canti brakes re CRC are a waste of time on touring bikes unless you ride flat bars & mountain bike levers.

This is because road levers do not have enough cable pull for their operation hence why you need the old style non low profile version or do what a couple of my friends have done and take the canti bosses off completely and use the newer dual pivot action side pulls.

My low profile cantis have worked fine for 20 years on my tourer. True, the new brake blocks have started squealing at the front, but I suspect I can sort that.



The snag with low profile cantis is that a lot of the mechanical advantage (MA) comes from Sheldons straddle wire trick. These brakes are therefore extra sensitive to straddle height.

Very true; to the extent that the fixed straddle wire usually sold with modern canti's is very likely the source of their mechanical inefficiency. The adjustable straddle wire is really the only proper way to set these brakes up.

Many years ago I bought some Avid Shorty canti's and they came with one (rather long) straddle wire - and no instructions. At the time, I had no problem with said wire, with the brakes operated from flat bar road brake levers. But when I changed the handlebars to drops the braking efficiency dropped alarmingly. Soon after, I bought another set of Shortys, but these came with instructions stating that you should choose from the two different length of straddle wire included depending on your bike's set up. I immediately took the shorter straddle wire and attached it to the existing dropped barred bike and hey! - braking power back to normal.

As an aside, I wonder why the flat bar brake levers were so effective, compared to the drop barred levers, even though they pull the same amount of cable? Cable routing perhaps?

User avatar
531colin
Posts: 12572
Joined: 4 Dec 2009, 6:56pm
Location: North Yorkshire

Re: Tektro cr520's on a galaxy

Postby 531colin » 5 Nov 2010, 12:07pm

CREPELLO wrote:
As an aside, I wonder why the flat bar brake levers were so effective, compared to the drop barred levers, even though they pull the same amount of cable? Cable routing perhaps?


Shimano did something to the flat bar levers (altered the pivot position?) so that at first they pull a lot of cable to get the blocks close to the rims, but as they approach the bar they pull less cable, to compensate for the decreasing MA of the brake itself. I remember CJ posted this information, but I can't remember where!!

User avatar
gaz
Posts: 13882
Joined: 9 Mar 2007, 12:09pm
Location: Kent, car park of England

Re: Tektro cr520's on a galaxy

Postby gaz » 5 Nov 2010, 12:50pm

531colin wrote:I remember CJ posted this information, but I can't remember where!!


Here. :)
2020 : To redundancy ... and beyond!

rich100
Posts: 105
Joined: 24 Oct 2011, 12:24pm

Re: Tektro cr520's on a galaxy

Postby rich100 » 22 Sep 2012, 9:37pm

Thread revival, hope it's ok to do so.....

I'm having this problem with the space on the forks of my Randonneur.

I fitted some tektro cr520's I had spare and realised not enough clearance for the pads. Back to the drawing board (again lol).

Does anyone know if either the BR-r550's or the cx50's would fit? I think the cx50's can use different size spacers, has anyone tried these yet and do they come with the different spacers in the box?

Alternatives may be to source older style canti's, or maybe even sell the drop bars and sti's I've bought for the project and go with trekking bar/vee brake combo, could be tempted.

Thanks

User avatar
CREPELLO
Posts: 5558
Joined: 29 Nov 2008, 12:55am

Re: Tektro cr520's on a galaxy

Postby CREPELLO » 22 Sep 2012, 9:48pm

If the brake studs are very close, you'll have the same problem fitting V brakes. Can you measure the distance C-C between the studs?

If your fork is narrow at the crown, it plays havoc with brakes with modern long V pads. You need to find a brake (or brake pad/shoe) that puts the pad further forward to clear the fork blades.

I think the best solution would be to look around for some old brakes that use shorter blocks and the old post mount block, rather than the modern threaded post mount.

Brucey
Posts: 36763
Joined: 4 Jan 2012, 6:25pm

Re: Tektro cr520's on a galaxy

Postby Brucey » 22 Sep 2012, 9:49pm

when you say not enough room for the pads with the 520s, do you mean that the bosses are too close together, or that the brake blocks clash with the frame, or that the brake blocks don'tmove far enough back to get the wheel out?

Any pictures?

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

rich100
Posts: 105
Joined: 24 Oct 2011, 12:24pm

Re: Tektro cr520's on a galaxy

Postby rich100 » 22 Sep 2012, 10:04pm

It's as if the brake arms are spread too wide, seems the combination of narrow boss distance (will try to measure tomorrow, but earlier post suggests Rando's have a gap of about 60mm?) and wide wheel (Alex ta19, website says about 24.5mm) and the spacers on the pads mean that even with the pads at lowest point and tilted down only just make the rim as way too close. The pads also do indeed clash with the forks, I didnt check if the tyre would have clearance to drop out when released).

OK so if likely to get same issues with V's I'll forget that option.

This: http://techdocs.shimano.com/media/techdocs/content/cycle/SI/Cyclocross/SI_8K50A/SI-8K50A-001-Eng_v1_m56577569830749996.pdf suggests that the cx50's or cx70's wouldn't do it either, shame.

Looks like retro canti's only option then...

Thanks

ps will try to get pics also and post tomorrow