Morimorimori

Hi, everybody.

I'm an unfortunate owner of Montague Urban bike which didn't came with a fork equipped with clamps for disk brakes, despite this model has those in their advertisement materials (pictures on the official site, several their videos on youtube and vimeo). I really looked forward to it as I planned to change stock brakes to disks right after purchase. Montague already said they won't be able to provide me a compatible fork of their own, not even for additional money, and when I tried to complain about them false-advertising about this model having those clamps and then forcing me to solve my problem myself, they stopped answering. So I'm on my own now.

I know that it's possible to weld those clamps onto any fork, yet I'm a bit hesitant for such radical measure, as I've learnt that if a fork wasn't initially designed to sustain forces applied by disk brakes, it may crash, presenting a threat to rider's health.

The stock fork has next dimensions:

Axel to crown: 400-405mm (yet their representative told me I need to look for a fork with length 380mm, for some reason)
Rake: 43mm

So I need a fork with next specs:

1. A-t-C and rake as close to the original as possible (I'm not quite sure how important is that, but I've seen a lot of statements that changing A-t-C length by 1-2cm can be felt immediately, and can change geometry of a bike to worse)
2. 1-1/8, NOT tapered
3. Disk brakes mounts
4. Material: I need the fork to have CrMo or steel steerer tube (because I would like to install SpeedLifter T14 Classic at this bike, and this one - 14cm - version can only be installed into a steerer with internal diameter of 25.4mm; according to the document, such internal diameter is only found at forks with steel steerer tube; I've already tried to put it into an full-Alu fork borrowed from a friend, and it didn't fit into its hole, it's a bit wider than the hole itself because it seems Alu tubes must have wider walls, to withstand load)
5. Weight: it must not be too heavy, not more than 1kg after the steerer tube is cut, the less - the better
6. Price: 150$ max

May be somebody will have a good suggestion? Or may be I'm over-complicating things and should just try to weld disk brake mounts onto this fork, after all?

Morimorimori

Just for the reference, here is the bike's in question page: link

One thing that bothers me in particular when it comes to selecting a proper fork is this:


Please note this strange wide cap serving as fork's crown - it's sort of a cone, and its widest diameter matches external diameter of the head tube. The problem is that almost all rigid forks I've seen so far in different stores don't have anything like this. A typical crown of such fork looks like this:



Sometimes it's even more narrow, like if steerer's tube is going straight out of legs.

1. What purpose does this cone of original fork serve? Is it simply for decoration, or it's some special type of a fork's crown and I need to find a fork of the same kind?
2. Will a regular fork fit such head tube at all? Though even if it will, this will surely look pretty ugly.
3. Will this head tube even accept a regular 1-1/8 (non-tapered) fork? May be it's for a tapered fork, after all?

So far, I was able to find only one fork which seem like it may more or less fit to this wide bottom of the head tube's lower cone. It's RST RF-M7 link
As you can see on their site, it has this rather wide crown's base, which I believe will fit more or less my head tube's base. But it has several issues, still:

1. Its A-t-C is 408, which is a bit more than the original fork
2. It's full-Alu fork, so I won't be able to fit SpeedLifter device into it, most likely.
3. It's not CrMo fork also, and I would like it to be CrMo for a bit better suspension steel offers.

nfmisso

The RST fork large diameter top is cosmetic. You will have to drop your bikes fork to verify that it is also cosmetic.

I like these:
https://www.bikenashbar.com/cycling/...rk-ns-cmf-base
https://www.bikenashbar.com/cycling/...rk-ns-ctf-base

As you are not using V brakes, you can ignore the 26 and 29 designations, and just look at the A-t-C specifications. If you want to you grind off the brake posts, or use them for a front rack.

cobba

Close to the specs you want: https://surlybikes.com/parts/forks/straggler_fork

Morimorimori

Hi, nfmisso.

I've actually reviewed the forks you mentioned, and reviews there reveal an issue with weight:
That's a bit too much, even for a steel a fork.

I'm more inclined to buy Soma CX forks, they are a bit costy (130-150$), but the brand seems to have good reputation. But both Soma and this one forks have the same issue I mentioned - their crown is very narrow, and head tube of Urban - even if it's just cosmetics - is quite wide. I believe such combination will look very comical/lame, at least. But I just can't find a CrMo fork with such wide plate at its crown..

Morimorimori

Thanks, cobba (and thank you a lot for your patience with my previous issue). Yes, I've seen this as well, and though I agree it's almost perfect match (except for this narrow crown issue, again), I find its design pretty ugly I just can't bear looking at it, whatever stupid it may sound. The bike's design doesn't help it as well, as it all curvy and smooth, and this fork is all pointy and "linear".

As I mentioned, Soma CX fork so far seems like the best match among CrMo forks. It has curvy/smooth design, looks very nice and has very close specs (but again narrow crown's plate, otherwise it would fit perfectly). Also it seems to weight around 1kg when cut, may be even less.

LesterOfPuppets

Maybe you could return the Urban and get a Fit.

https://www.montaguebikes.com/product/fit/

Morimorimori

That's when it gets complicated. I'm from Belarus, small state bordering Russia. We don't have Montague dealers here, I couldn't buy it anywhere in our state (it's a poor little state, we are of little interest to anybody, and demand for such costy bikes is low), so I ordered it from Russia. It was a bit hard to find a store which would sell it abroad even there, so selection was pretty limited. I wanted to buy Navigator initially, but wasn't able to find frame's size I needed. Then I saw that Urban at some store, at decent discount, checked Montague's advs for it, saw it has disk brake mounts on front fork on pictures and thought I'll buy it and with money I'm saving just upgrade it later.

Didn't play that well, in the end Returning it now would be.. rather difficult. As far as I know that store is not even official dealer (yet I've verified the bike is not a counterfeit). At least it has disk mounts on the rear fork, so it's not utter disaster.

AnkleWork

Some problems just don't have solutions.

csport

Assuming the wheelbase (distance from the front to the rear axle) is 1m and keeping things simple, 1cm change in the ATC will result in the headtube angle change of 1cm/100cm == 0.01. Converting it to degrees yields 0.01 * 180/pi = 0.5 degree. Does this matter to you? We do not know. Larger angle (shorter ATC) will make it handle mor like a road racing bike, smaller angle will make it closer to a MTB. Also, longer fork will put more stress on the frame which may exceed manufacturers' specs and pose risks to one's health.
You can look at some road/CX/touring/MTB models and see what headtube angle they have. Trek, Specialized and other large brands publish geometry of their bikes on their websites. This wil give you some idea of how much is too much.

You can read Sheldon Brown's page on headsets: Servicing Bicycle Headsets
Then look at the cribsheet and find which one you have: Sheldon Brown's Bicycle Headset Dimension Crib Sheet
I suspect that you have ZS44 (inner diameter of the head tube is 44mm ), which has 30mm crown race inside diameter. Steel forks you are looking at also have 30mm inner diameter of the crown race and 1 1/8" steerer. As you said, they may look ugly in a thicker aluminum tube. They are made for EC34 standard, which is common for steel frames. Apart from the ugliness, they should fit ZS44 headset. As @nfmisso said, you should take out your fork and measure it yourself to confirm these facts. Also, you can measure the ATC yourself: https://www.sheldonbrown.com/rinard/forklengths.htm to verify what the representatives say.

I like Soma and I actually have a Soma bike with a lugged CX fork. Soma forks are made by Tange, the tubing used is mostly Tange Infinity. You can look for Tange forks, maybe even Tange Prestige: https://www.treefortbikes.com/Tange-...ork-Disc-Canti -- they say it is 957g with uncut steerer. Though I think a lugged fork (including the mentioned Straggler fork) does not belong on this aluminum bike aesthetically. Be sure to check tire clearance.

wsteve464

Find a local frame builder and talk to them about putting one of these on the fork

BK2009

Morimorimori

I'm kinda doubt our state has a developed movement like that, even in much more developed Russia this trend is still in its infancy. But we have private workshops which accept orders for different kind of metal works, so I could try my luck there. One thing that bothers me is that to firmly attach something like this to the fork, they will have to weld it to its crown. And welding may weaken its structure..

JohnDThompson 

Might not be a good idea unless the fork blade is sturdy enough to accept disk brake forces without bending.

squirtdad

OP, I am treating this like work: Is there a real problem here? Is the braking that horrible that it you have to go to disks?

Understand that you want to have disks, but what will the actual gain/improvement be over the current calipers? Is that gain worth it tor the cost and aggravation?

Another (probably minor) consideration is to make sure any fork change is similar to the original so you can fold the bike.