Currently using a Dura Ace 9000 front caliper (Front only as Fixed) with Continental GP4000sii 700x25
Now we all know these tyres measure bigger than they should.
I want to fit 28s.
Plenty of clearance on the rear as I had the frame made to accommodate although might lose a smidge of dropout usage.
On the front, I have plenty of fork clearance but not enough between tyre and caliper.
Wheels are 25mm wide (external) carbon so tyre 'height' is about going to be about 1mm from caliper.
Should I just stick with a 25 on the front or can anyone recommend a caliper that may offer better clearance?
I have 25mm gp4000 on a 23mm rim using DA7800 with ample room.
Depending on yer budget, tektro r539 (budget), trp equivalent (more spendy), and VO Grand Cru, all will fit at least a 32mm tyre.
They're deep drop, no?
Dura Ace 49mm, VO 47-57mm.
You mean 39-49mm. You can't recomend someone with a standard caliper frame, deep drop brakes without knowing the brake drop. I have two standard drop frames and neither would work with what you have advised. Bad advise is worse than non.
Apologies. Someone needs to untangle their knickers though.
Nah, I'm chill. Just calling out bad advise.
All latest shimano 7000,8000 and 9100 clear 28s
Then I will amend my advice, @aniki, if you have sufficient drop on your forks to accommodate 47-57mm drop brake calipers then Tektro r539...........
Bjf, Still think yer knickers need untangling, maybe just a little, but that could be bad advice too.
Ah but these 28s are different...
So you're essentially looking for something that has the minimal amount of caliper directly below the mounting bolt. That is unless it's the sides/shoulders of the tyre that is rubbing rather than the top, which is it? I had a similar issue with a rear, single pivot Campag Record caliper, which I sorted by fitting a dual pivot, old(er) school Centaur caliper instead.
As far as I can see the DA9000 already has quite a big cutaway arch to give good tyre clearance, so I can't see how you're going to improve much on that. If you're having tyre-caliper clearance issues, you'll probably also want something with very little drop, so that limits your options too.
This is with a 25 which measure about 27.2. Yes @ffm you’re correct in that I think I need something with a smoother profile. In this pic it looks like the two pivot bolt sections will foul a bigger tyre rather than the actual arc at the top of the caliper. I’ll get the 28 mounted in a day or two to make sure.
Annoyingly the DA9000 is just listed as having a drop of 49mm, which isn't much use as what you want to know is the range of the drop. It doesn't look like you're actually super-tight on the top, so maybe you don't need a caliper with a really short drop. I've got a front Tektro R316 going super cheap which you could try. I recently sold a matching one for someone to fit to a super-tight fork and it seemed to work for them.
I ran shimano r650 brakes with 28c GP4000 II tyres. Clearance was good.
Ok thanks for that. I’ve ordered one tyre which I should have time to mount on Wednesday night so will see how it looks; take another photo and go from there. If it’s a total failure I can still use the 28 tyre on the back and just keep a 25 on the front.
Alternatively, see if @Julian_Stock still has these Campag Centaur calipers for sale. Those are the ones that I found gave me enough clearance over a 28mm GP4000s
Do you know what the internal wheel width was with this combination? This is what’s causing me a problem as the wider wheel makes the tyre taller.
Ah good point. It was the previous generation Mavic Open Pro rim, so pretty narrow. Don't have the bike anymore so can't take measurements for you I'm afraid.
I had a drilled track fork that bottomed out onto the tyre with every Shimano caliper i tried. Found a Sram Rival caliper that cleared fine. Now i have a Rival caliper on a Columbus Fel fork (365mm A-C) with a 30c G-one on wide carbon with no clearance issues. If you're anywhere near Sydenham you're welcome to come try the fit.
Not mine and not a GP4000 but the last slide might help, shows R8000 caliper clearance.
I've got a set of R8000 calipers I would happily sell. They came off a bike with 28c GP4000 IIs so can absolutely confirm they fit.
So the verdict; not a hope in hell of these tyres fitting!
Looking at the pic of the 25 it does look like there’s a reasonable amount of clearance. This is with a year of stretch and about 4000 miles of wear.
The 28 however, on my wheels anyway, is absolutely MASSIVE.
The width got bigger but still with about 1mm clearance at the fork but the height!! The height grew so much that the wheel wouldn’t even fully locate in the dropouts without the tyre hitting the caliper.
Fair to say that there’s no way this will work whatever caliper I use.
Thanks for all the help. The 28 hasn’t gone to waste as it fits the rear just fine.
Actual width is about 31mm.
Yeah that's tight! For reference a Shimano wouldn't work on my setup but a Sram did. Terrible pic but below shows a 30c g-one on Kinlin rim, there's probably 2-3mm clearance all round on a shortish A-C length fork. Essentially the inside of the caliper runs flush with the inner surfaces of the fork so if the wheel will spin without a caliper it should/might work with a Rival caliper.
I'd stick with the 25c and DA caliper.
You could put something in the dropout to give you 2mm more of crown clearance. Of course this could be terrible advice, but may work if done right (and the dropout have enough room to do it safely)
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