Which mudguards and dual-pivot brakes for 32mm tyres?

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jackt
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Joined: 30 Jul 2008, 11:13pm

Which mudguards and dual-pivot brakes for 32mm tyres?

Post by jackt »

I have a 2007 Salsa Casseroll that supposedly has clearance for 35mm with guards.

I'm looking to fit 32mm tyres with guards and would appreciate advice on which combination of guards and dual-pivot brakes will fit.

The bike has currently got 28mm tyres and SKS 35mm guards. I suspect SKS 45mm guards won't fit, though I've not tried as I don't have a pair on hand. Am looking at Kinesis Fend Off in 40mm size. Will a dual pivot brake fit around that? Other mudguards to consider?

thanks!
AndyK
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Re: Which mudguards and dual-pivot brakes for 32mm tyres?

Post by AndyK »

OK, if it the Casseroll has that clearance presumably it takes a long-reach brake. What brakes does it have fitted at the moment? Do you know what the frame's "reach" (AKA "drop") is? (Guide to measuring reach here.)

I've always been very happy with my Tektro R539 brakes (reach 47-59mm) but they would struggle with 32mm plus guards. The even-longer-reach R559 would probably cope: that has a reach range of 55-73mm, so provided the reach on your bike is at least 55mm that might be a good option. Besides the length its arms bow outwards and thin out to allow more tyre clearance widthways.
The other factor is whether the frame and forks will allow for that width of tyre. If Salsa said they will, I guess they will!
scottg
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Re: Which mudguards and dual-pivot brakes for 32mm tyres?

Post by scottg »

AndyK wrote: 24 Mar 2023, 12:55pm[snip]

I've always been very happy with my Tektro R539 brakes (reach 47-59mm) but they would struggle with 32mm plus guards. The even-longer-reach R559 would probably cope: that has a reach range of 55-73mm, so provided the reach on your bike is at least 55mm that might be a good option. Besides the length its arms bow outwards and thin out to allow more tyre clearance widthways.
I used the 559 version with 31mm tyres and SKS guards, the 559 is wider than the 539.
I had the pads nearly at the top slots on the arms, say 56mm reach.
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slowster
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Re: Which mudguards and dual-pivot brakes for 32mm tyres?

Post by slowster »

A quick online seach (various links below) suggests that the frame/fork was designed to be used with 47mm-57mm calipers (what I call 'medium' drop). In particular the image here https://www.mtbr.com/threads/casseroll- ... 11&slide=5 shows a medium drop brake with pads at the bottom of the slots, and comes from this 2007 thread - https://www.mtbr.com/threads/casseroll-anybody.298511/.

It appears therefore that Salsa followed the approach of many framebuilders in designing the fork especially to maximise clearance with medium drop calipers, similar to many audax frames. With those frames, the maximum tyre width with mudguards is usually 28mm, and the tolerances for even that width are tight, i.e. the fork axle to crown length needs to be fairly precise to result in the pads being at the bottom of the slots to maximise tyre clearance .Therefore I am extremely sceptical that you will be able to fit 32mm tyres with mudguards, especially not with a satisfactory/safe gap between the mudguard and tyre under the fork crown, despite Salsa stating otherwise on their website.

I would not try to use Kinesis Fend Off mudguards with a medium drop dual pivot caliper. I think they are both too wide to fit (the brake arms will squeeze the mudguard), and the trapezoidal profile is not suited to close clearance rim brakes (the flat top profile of the mudguard means it has to be lower than a round profile mudguard, making the mudguard/tyre clearance even worse). The standard round profile SKS Chromoplastic or Bluemels mudguards works best with medium drop dual pivots, and even with those I think you might not be able to fit larger than 35mm mudguards (which would be the normal size to use anyway with 28mm tyres). SKS Chromoplastic mudguards used to have a squared off profile, but I think they all now have a round profile, even the 35mm (probably to make them fit modern dual pivot brakes better).

I don't think Tektro R559 53mm-73mm long drop calipers are a viable solution to enable wider tyres to be used, because the limiting factor will be the clearance under the fork crown, and longer drops will not change that. However, they do offer two possible benefits over a medium drop caliper:

1. Because the arms project further outwards to accommodate a wider tyre, they should potentially accept a somewhat wider mudguard without the arms squeezing the mudguard.

2. Positioning pads at the bottom of the slots reduces mechanical advantage. With the R559 the pads would have to be at the top of the slots (indeed if the Casseroll fork manufacturing tolerances are off/depending upon the positioning of the rim's braking surface, you might need to file the brake slots slightly), which increases mechanical advantage (e.g. see the comments of this poster here - viewtopic.php?p=957906#p957906).

Finally, if you plan to use modern NSSLR Shimano STI levers, then you need to choose a brake that is suited to them. Brucey made a very useful post on that here - viewtopic.php?p=1538015#p1538015.


https://www.salsacycles.com/bikes/archived_casseroll

https://www.bikeradar.com/reviews/bikes ... lideshow=1

https://pezcyclingnews.com/technspec/sa ... imes-roll/
pwa
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Re: Which mudguards and dual-pivot brakes for 32mm tyres?

Post by pwa »

One has to remember that there will be a set distance between the top of a particular tyre, and the bolt hole in the fork crown for the brake and possibly the mudguard. That distance is essentially what limits tyre size and guard choice, and it isn't increased by getting longer reach brakes.

Have a look at the shape the bottom edge of the brake arms make when the brake is applied. That shape gives you an idea of the mudguard profile that will fit closest to the brake.
jackt
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Re: Which mudguards and dual-pivot brakes for 32mm tyres?

Post by jackt »

Thanks all for the replies - very helpful.

The current brakes are Tektro R730 (medium drop 47 to 57mm).

I guess I'm on the lookout for some 40mm mudguards with a round profile. Perhaps aluminium would be an idea as it'll be easier to indent them a little to make them fit inside the brakes, if necessary.
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andrew_s
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Re: Which mudguards and dual-pivot brakes for 32mm tyres?

Post by andrew_s »

Both brake drop and clearances are fixed properties of the frame/fork, and can only be changed by buying a new frame/forks.

Brake drop is the difference between the distance between axle & brake bolt centres and the distance between the axle centre and the centre of the rim braking surface (which is normally close to half the bead seat diameter - i.e. 311 mm for 700c wheels).

The largest tyre you can use is the brake drop minus the distance between the brake bolt centre and the underside of the fork crown (or the cerntral underside of the caliper if that's lower, as it often is, for rear brakes especially), minus the thickness of the mudguard and any space above it, minus 5-15 mm of safety clearance, minus any excess of tyre height over width (eg the 5 mm of blue anti-puncture rubber in a "plus" tyre).

The brake drop figure of a brake is an indication of which frames it's usable with.
You don't get any extra clearance by buying a brake advertising a bigger drop figure.
slowster
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Re: Which mudguards and dual-pivot brakes for 32mm tyres?

Post by slowster »

I've added below the image from the link in my post above. I think the brake shown is a 47mm-57mm medium drop model, such as Shimano BR650.

Have you tried fitting the tyres you want to use to see what the clearance is with the existing brakes? If not, I suggest you do so before anything else. Based on the photograph below I doubt you will be able to use a tyre wider than 28mm with mudguards: that has always been generally accepted as the maximum practical tyre size with pads at the bottom of the slots on a 47mm/57mm caliper, and even that is dependent upon the fork axle to crown length being specified to achieve just that.

Another potentially limiting factor is the fork crown design itself. Some cast fork crowns will not accept a mudguard wider than 35mm. The Casseroll has a unicrown fork, which introduces another potential issue - variation in the amount by which the steerer tube extends below the hole for the brake bolt. The maximum mudguard/tyre clearance is usually achieved with a round profile mudguard pressed up against the underside of the brake caliper arms, but with a unicrown fork the steerer tube may force the mudguard to be lower.

Image
jackt
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Re: Which mudguards and dual-pivot brakes for 32mm tyres?

Post by jackt »

Thanks again, very useful info and good practical advice.

Turns out scouring the web for images of the same bike isn't bad way to go. There's a Casseroll on eBay, with some photos that look very much to me like SKS 45mm and Tektro R538 brakes. Not sure on the tyres, but I think at least 32mm. There's hope!
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jackt
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Re: Which mudguards and dual-pivot brakes for 32mm tyres?

Post by jackt »

Slightly confusing is that my Tektro R730s seem to be regarded as 'medium drop / reach' while those Tektro R538s are described as 'long drop / reach ' - even though for both models the drop is given as 47-57mm.
slowster
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Re: Which mudguards and dual-pivot brakes for 32mm tyres?

Post by slowster »

jackt wrote: 25 Mar 2023, 8:17am Slightly confusing is that my Tektro R730s seem to be regarded as 'medium drop / reach' while those Tektro R538s are described as 'long drop / reach ' - even though for both models the drop is given as 47-57mm.
There is a bit of history involved, and the eras are somewhat approximate:-

In the 1960s even side pull brakes fitted to race bikes had large clearances. In the 1970s Campagnolo and others introduced close clearance brakes with a short drop, which Campagnolo distinguished by the designation 'piccolo'. For a while both the original versions (often called 'standard') and the piccolo model were available, but during the 1980s the standard versions were discontinued, and the short reach, close clearance versions were all that were made for racing bikes and became the new 'standard'. There were still some larger drop/clearance brakes for touring bikes, such as Weinmann centre pulls.

In the 1990s Shimano introduced 47mm-57mm drop versions of a couple of its brakes (BR-650 equivalent to Ultegra spec., and BR-451) to cater for a largely UK led demand for brakes that would accomodate mudguards with 23mm-28mm tyres on audax bikes. Because they were longer than short reach racing brakes, they were generally referred to as 'long drop'. In reality it was always a bit of a misnomer, and I think there has been a tendency by many (me included) over the last decade or so to call them medium drop, not least to distinguish them from the Tektro R559 and its predecessor, R556.

It is one of those situations where it is better and safer to quote the actual specification/measurement, e.g. 47mm-57mm, rather than descriptors like short, medium and long.
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andrew_s
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Re: Which mudguards and dual-pivot brakes for 32mm tyres?

Post by andrew_s »

47-57 drop brakes were introduced as an option on the RX100 groupset, with the BR-650 & BR-451 being introduced when the RX100 groupset was dropped. The BR-451 brakes were advertised as RX100 brakes by shops for several years after the change.

Edit:
having checked, the RX100 brake was replaced by the BR-550, with the BR-650 as an upmarket alternative. The BR-451 came later.

(RX100 was functionally the same as 105, but had a cheaper finish)
Last edited by andrew_s on 27 Mar 2023, 10:34pm, edited 1 time in total.
PH
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Re: Which mudguards and dual-pivot brakes for 32mm tyres?

Post by PH »

The reviews say, in standard spec, the bike had Salsa's wide rims (Possibly re-branded Velocity), quite common now, but Salsa seemed to have been ahead of the curve. These would have given the tyres a wider lower profile, maybe enough to go up a tyre size if the other factors were optimised. They'd need to be set for the blocks to be at the bottom of the slot, which is rim specific and also limits adjustment for wear. Also, some frame builders are better than others at getting the brakes perpendicular to the rim, anything less than perfect eats into the clearance.
I've never had a bike that took 32 mm tyres and 57mm brakes, I had a SOMA ES which was the closest, that would take 30mm Marathon Racers which measured accurately on Open Pro rims. I've also had a bike with the same brakes which would only take 25mm tyres and guards.
Re which guards, you may get 32mm tyres under SKS 35mm guards, I haven't tried, though I'm currently running a 40mm tyre under a 45mmm guard, not ideal, but not an issue either.
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