Tektro cr520's on a galaxy

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Brucey
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Re: Tektro cr520's on a galaxy

Postby Brucey » 22 Sep 2012, 10:18pm

If you use XTR-lookalike pads like these

Image

they are dead skinny and may well slip between the rim and the forks OK, but you may still need to deflate the tyre (or remove a brake block) to get the wheel out.

These pads are thin already but can also be made thinner where it matters (to compensate for bosses that are too close to one another otherwise) by removing the inner curved washers and replacing them with a single thinner spacer that is filed to the correct wedge shape. Turning the spacer slightly means that you can trade angle for toe setting when fine tuning.

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531colin
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Re: Tektro cr520's on a galaxy

Postby 531colin » 22 Sep 2012, 10:24pm

Image

These fit narrow canti studs . E bay....no connection...

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gaz
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Re: Tektro cr520's on a galaxy

Postby gaz » 22 Sep 2012, 11:40pm

Retro Canti's like the Deore XTs in the picture take a stud type brake block. Cartridge pad versions are available.

On the set in the above picture a cartridge pad version would be unsuitable at the front, the cartridge is too long. Standard canti blocks are still available which are short enough to sit in front of the fork rather than needing to squeeze between the fork and the rim.

I have the same Deore XTs on my Jackson. I use the cartridge type at the rear but they won't squeeze in with a Sputnik rim at the front, so it's a standard set of blocks and faff around with the toe-in every time they wear down :evil: .
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Brucey
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Re: Tektro cr520's on a galaxy

Postby Brucey » 23 Sep 2012, 6:50am

rich100 wrote: 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...


V's and BR-R550s both have the pads mounted similarly, i.e. on a face that is set inwards from the boss by about 7mm or something. Actually the CR520s are similar, too. Maybe they can be made to work in some cases with an unusually skinny pad.

You are within a few mm of making it work with the CX50 with the smallest spacer fitted. I wonder what would happen if a non-approved even smaller spacer were fitted?

It could be that the brake arm might then be in danger of fouling the tyre directly with any of these brakes if skinny pads/smaller spacers are fitted; it would be a case of having a go.

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531colin
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Re: Tektro cr520's on a galaxy

Postby 531colin » 23 Sep 2012, 7:33am

This works...

.Image

stud type KoolStop Cyclo cross pads are "road length" so clear the forks with the old type cantis I linked earlier.

rich100
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Re: Tektro cr520's on a galaxy

Postby rich100 » 24 Sep 2012, 7:20pm

Thanks for the info

So if i find some brakes that take the stud type I should be fine then? It's the extra washers on the threaded type that's reducing the space too much?

These should do? : http://www.ebay.co.uk/itm/Shimano-Alivio-Bike-Cantilever-Rim-Brake-Set-P6-Brand-New-/290777473348?pt=UK_sportsleisure_cycling_bikeparts_SR&hash=item43b3b02144#ht_2272wt_1344

Brucey
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Re: Tektro cr520's on a galaxy

Postby Brucey » 24 Sep 2012, 7:33pm

I reckon they will fit, but the arms will stick out a lot more than normal with the stock blocks and maybe stick out a little more than normal even with low profile brake blocks. You may need a longer straddle cable to make it work at all; the arms sticking out is isn't necessarily a bad thing for brake power, but can cause problems if they stick out at the back. They won't stick out any more than 520s though...

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531colin
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Re: Tektro cr520's on a galaxy

Postby 531colin » 24 Sep 2012, 8:37pm

NO NO NO

You want brakes this shape

Image

made in the days when forks were made with the bosses close together, with the Koolstop pads I linked to finish the job

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CREPELLO
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Re: Tektro cr520's on a galaxy

Postby CREPELLO » 24 Sep 2012, 8:47pm

531colin wrote:NO NO NO

You want brakes this shape

Image

made in the days when forks were made with the bosses close together, with the Koolstop pads I linked to finish the job

I don't know. They may be superior in geometry (are they medium profile?), but as far as I can see, the Alivios Rich100 posted to would work - just maybe not as well. The pads project further foreward, so they should clear the fork blades.

An important factor with those Alivios (and the XT's above) is the fixed length straddle wire. Given an adjustable straddle I'm sure they would probably work.

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531colin
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Re: Tektro cr520's on a galaxy

Postby 531colin » 25 Sep 2012, 11:26am

Have a look here http://forum.ctc.org.uk/viewtopic.php?f=5&t=43448&hilit=un+pair+humpty+dumpty&start=15, I posted some pictures of the exact set-up I'm talking about, old fashioned Shimano cantis and KoolsStop cyclo x pads on an old fork with narrow canti studs.
Subsequent to setting up this brake, I have learned from the good folk on this very forum that I could get a little bit more power by raising the brake arms (ie setting the pads right up tight to the arms on their stalks)
These are mid profile cantis (cable attachment a bit higher than the pads), I think these are the best compromise for drop bar levers. (good power, reasonable pad clearance, action is bound to be regressive, but not enough to spoil the brake.)
[Low profile give the most power, but regressive action means constant adjustment, wide profile give the best pad clearance.]

rich100
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Re: Tektro cr520's on a galaxy

Postby rich100 » 25 Sep 2012, 9:59pm

OK thanks for the info, I'm going to give those Alivios a try, low cost and new stock so springs should be ok, I'll keep my eyes open for some NOS of the XT type though maybe.

Think i need to print all this info out and spend some time setting them up as best as possible...

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531colin
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Re: Tektro cr520's on a galaxy

Postby 531colin » 25 Sep 2012, 10:36pm

Alivios are low-profile.....the snag is regressive action, ie the mechanical advantage reduces as you pull the lever and the straddle wire goes up.
regressive action....you get a high mechanical advantage when the straddle is low, which reduces as the straddle raises....the opposite of what you want, which is a high MA when the pads strike the rim.
You can reduce the regressive action by setting the arms wide apart, like this home modified brake....the barrel adjuster in the straddle also helps by keeping the straddle low while taking up pad wear.

Image

Ribblehead
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Re: Tektro cr520's on a galaxy

Postby Ribblehead » 26 Sep 2012, 10:06pm

For what it's worth I have three bikes with cantilever bosses, the spacings are:

Tektro RX5 mini V's with a 22mm wide rim
Front bosses centre-to-centre 79.5mm
Rear bosses centre-to-centre 76.5mm
Inside fork spacing 54.5mm
Inside seat stay spacing (midway between brake blocks and brake bosses) 62mm

If the inner/outer spacers are swapped over on these brakes then they will accomodate a 24mm rim at the boss spacings I've listed.

Late 1980s Weinmann cantis with a 24mm wide rim
Front bosses centre-to-centre 62mm
Rear bosses centre-to-centre 70.5mm
Inside fork spacing 51.5mm
Inside seat stay spacing (level with brake bosses) 77mm

Shimano LX V-brakes circa year 2000 with a 21.5mm wide rim
Front bosses centre-to-centre 80mm
Rear bosses centre-to-centre 79mm
Inside fork spacing 80mm
Inside seat stay spacing (just below brake bosses) 86.5mm

Edit: They're not Shimano LX, they're Shimano STX RC