SRAM Red Brake Clearance

[Cat2forLife]

Its not the caliper that is the problem, its where the mount hole is in the frame, its too low.

 

That is why I am asking where the brake shoes are sitting.

 

I even Photoshopped a nice picture for you to see what I mean.

 

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[Mongoose!]

narrow rims (on a road bike) are not made for wide tyres.

 

Makes me think of a VW ad a while back. "Just because its works fits, does not make it right..."  

 

[Schnavel]

That is why I am asking where the brake shoes are sitting.

 

I even Photoshopped a nice picture for you to see what I mean.

 

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I will take some photos this evening and then post them up tomorrow morning.

 

Interested to see if the spacers will solve the problem.

['Dale]

Atleast thorns wil be scraped out before penetrating too deep

Hehehe

Sharp ????

[Mongoose!]

I will take some photos this evening and then post them up tomorrow morning.

 

Interested to see if the spacers will solve the problem.

 en???

[Schnavel]

 en???

 

Sorry, it's been a busy day at work and haven't had a chance to upload pictures etc.

 

So I went home yesterday and had a look at the position of the brake pads on the caliper. It's not the best photo, but the pads are located half way along the slot, and not at the bottom, indicating that the caliper definitely sits slightly lower:

 

 

I then took off the brake caliper to check the mounting and it does sit rather low on the frame:

 

 

So from here I tried a number of things:

 

Swapped the front and rear tyres around (both brand new 28C tyres) - this appears to have given an extra mm of clearance for what ever reason.

 

I then added in two washers to help with the spacing:

 

 

There is also a small amount of play from the mounting hole which the shaft of the caliper runs through. I made sure to torque the caliper to 9nm while positioning it at the top end of the mounting hole.

 

Lastly, I tightened the grub screws which connect the springs to the calipers on either side of the brake arch and this appears to have pushed the "washer" part of the spring at the top of the brake caliper upwards.

 

As a result of all of the above, I now have about 2 - 3mm clearance between the brake caliper and the tyre, with plenty of clearance to the frame:

 

 

It's still not as much as the caliper on the front (5mm+), but it's sufficient to allow the wheel to spin without rubbing. I took the bike out for a ride this morning and it feels like I'm riding a mtb tyre due to the larger volume of these tyres - the road never felt this smooth!

 

I'm going to keep an eye out on the shape of the tyre as is appears that it may change as per information from the net. Hopefully it bulges outwards and not upwards, as there is plenty of space for the tyre to move outwards.

 

Edit: Spelling

[Captain Fastbastard Mayhem]

Great news!

 

As for the difference in circumference, it may be a manufacturing defect or tolerance issue. 2 tyres at either extreme of the scale

[shaper]

Thought the washers would do the trick due to the angle of the seat stays, you can always add more washers as your brake blocks are not on the limit and can move down further on the brakes.  Hopefully the simple fix has resolved your issues.

[Mongoose!]

Great news!

[Cat2forLife]

Glad it all worked out in the end! IMO, the mount screw looks a little low, but I can't tell you for sure if that's the case. It's just my opinion.

 

EDIT: Sorry, meant the mount hole in the frame looks a little low.

[Schnavel]

Glad it all worked out in the end! IMO, the mount screw looks a little low, but I can't tell you for sure if that's the case. It's just my opinion.

 

EDIT: Sorry, meant the mount hole in the frame looks a little low.

 

I also think the mounting hole sits a bit low in the frame, but I guess that's part of the design.

[Cat2forLife]

I also think the mounting hole sits a bit low in the frame, but I guess that's part of the design.

 

I guess we'll never know

[Schnavel]

I guess we'll never know

 

Anyone wanna buy my ultravox? 

[NotSoBigBen]

I guess a racing bike is built with 'racing' in mind and not commuting on balloon tyres?

[Cat2forLife]

Anyone wanna buy my ultravox? 

 

No thanks, the brakes sit too low on those bikes, I've heard.

[David Marshall]

I'm running the American Classic Victory 30 wheels (https://amclassic.com/index.php/wheels/victory-30-tubeless-pair.html) which have an internal width of 18,1mm and an external of 23mm, so not very narrow...

Haven't had time to follow this thread.  18 mm would be considered quite narrow these days.  Most of the carbon rims I see have an outer width of 25mm and inner wider than 18mm by 2-3mm