[JungleBiker]

Please excuse me if this question has been asked before on this forum.

In order to save weight I would like to put a carbon road fork on my hard tail MTB frame (which I ride on roads).

I reckon if I were to use a fork designed for 650 wheels (triathlon/TT style) but fitted with my existing 26 inch MTB wheels and 26 x 1 inch slick tyres my front end will be lower (too low - I think about 2 inches lower?).

If I fit a fork for 700 sized-wheels and use a 700c wheel, I think my front end will be about an inch higher.

Can anybody advise which option would give good results and how my steering will be affected? Am I right in thinking the 700 forks will make steering more stable and the 650 forks will make steering more twitchy?

Another related question - I would also have to fit a road brake - would this work with my V-brake lever?

In case anybody asks me why I don't just fit rigid MTB forks - the answer is I don't think I can get hold of MTB forks as light and cheap as I can get carbon road forks.

Many thanks.
Eddie.

 

[dirt diggler]

try a cyclocross carbon fork. or mtb rigid carbon fok like pace or wound-up.. also check out www.spicercycles dot com and see what Gene has to offer for your custom build

dirt diggler

 

[Cloxxki]

How long is your present fork?
700c road forks are 370mm, and need a road brake.
700c cross forks are most often 400mm, and take a V-brake or even disc.
Cross forks are often little lighter than light MTB forks.
Shortest rigid MTB forks are at least 390mm.
700c wheels with same tire height (like 25c) would add 31.5mm.
650c tires raise the front ~6mm over 26", and might work with a 26" V-brake setup.

Fork length doesn't 100% translate to front end height, as it's placed under an ~70º agle, but the difference is really small.

 

[JungleBiker]

try a cyclocross carbon fork. or mtb rigid carbon fok like pace or wound-up.. also check out www.spicercycles dot com and see what Gene has to offer for your custom build

dirt diggler

Hi Dirt Diggler,

Thanks for your reply. I just checked the link to spicers and looked at the cyclocross forks and confirmed what I suspected - that is, if I wanted one of the lighter forks it would cost me a small fortune, if I wanted to save money, the forks would be kinda heavy. I can get lighter and cheaper road forks.
Regards,
Eddie.

 

[JungleBiker]

How long is your present fork?
700c road forks are 370mm, and need a road brake.
700c cross forks are most often 400mm, and take a V-brake or even disc.
Cross forks are often little lighter than light MTB forks.
Shortest rigid MTB forks are at least 390mm.
700c wheels with same tire height (like 25c) would add 31.5mm.
650c tires raise the front ~6mm over 26", and might work with a 26" V-brake setup.

Fork length doesn't 100% translate to front end height, as it's placed under an ~70? agle, but the difference is really small.

Hi Cloxxi,

Sorry I don't have my bike here, though it is currently equipped with SID World Cup. But I do have another MTB bike here with rigid (heavy steel MTB forks) and they roughly measure about 400mm - like the cyclocross forks you mention. I assume most MTB forks are the same?

Looking at your other data, you say 700c wheels... would add 31.5 mm. But add to what? Do you mean wheel diameter or radius compared with 26 inch wheels with same (25c - or 1 inch?) tires?

I reckon you are wrong regarding 650 wheels raising the front because I think the 650 forks are shorter than MTB forks (because no need for huge tyre clearance)? I think the front end would be lower and the angle of the head tube steeper. I think this makes steering more twitchy, but I'm not sure, hence my question.

I know that if I fit a road fork I will need a need a front road brake, hence my question about compatability with a V-brake lever. I don't want to fit disc hubs/brakes because of extra cost/weight.

Thanks.

Best regards,
Eddie.

 

[Cloxxki]

31.5mm at the wheel axle, as 700c rims have 63mm on 26"
650c is 12mm larger in rim than 26", but 51mm smaller than 700c.

V-brake levers will offer a firm contact point with road brakes, but less power. You'd want a cantilever-specific lever.

Most MTB forks differ, some are suspension corrected, some not, some not, some are of random length. Your SID should be around 440mm or ~420mm after sag.

 

[jrm]

a 700c specific fork isnt going to be corrected

Please excuse me if this question has been asked before on this forum.

In order to save weight I would like to put a carbon road fork on my hard tail MTB frame (which I ride on roads).

I reckon if I were to use a fork designed for 650 wheels (triathlon/TT style) but fitted with my existing 26 inch MTB wheels and 26 x 1 inch slick tyres my front end will be lower (too low - I think about 2 inches lower?).

If I fit a fork for 700 sized-wheels and use a 700c wheel, I think my front end will be about an inch higher.

Can anybody advise which option would give good results and how my steering will be affected? Am I right in thinking the 700 forks will make steering more stable and the 650 forks will make steering more twitchy?

Another related question - I would also have to fit a road brake - would this work with my V-brake lever?

In case anybody asks me why I don't just fit rigid MTB forks - the answer is I don't think I can get hold of MTB forks as light and cheap as I can get carbon road forks.

Many thanks.
Eddie.

for suspension the way a MTB specific for would be. The difference in crown to dropout lenght whether its a 650 or 700c specific fork is going to put more bias over the front of the bike. The handling will be sketchy big time.

You could getthe same position using a flippable stem and drop bars or a flippable stem and a flat bar.

And no your v levers wont work with road calipers. The two pull different lenghts of cable.

 

[WOY]

I have contemplated the same issue before and decided I will use a road frame with flat bars.

I think for your case a 700c fork will be closer in diameter to a 26” with a 2” tire. It may still have a shorter crown to drop put length then say a short travel XC suspended fork however since it is essentially a road bike the steeper head angle is not going to be a problem and the lower BB will OK also.

One more question what rear wheels are you going to use? Don’t think Vs will be compatible with a 700c rim.

More on the V-lever (Shimano or Avids) and road brakes calliper, would the levers with leverage adjustment (eg speed dial) work any better?

 

[pimpbot]

I tried it once...

... in a fit of 'experiment gone awry', I put Avid SD7 levers and a flat bar on my road bike. THe brakes sucked. It was very hard at the lever with no decent stopping power, even with the Speed Dials dialed all the way in. You need to either find cantilever levers, or use a travel adjuster of some kind.

 

[Cloxxki]

Isn't it hard to get a roadbike with suficient toptube for a flat bar? I know they're being sold stock like that by the thousands, Road/CX frame, CX fork, flatbar, but the upright shorter position might kill it, or...?

 

[WOY]

Cloxxki you are right about the top tube length, I would get a frame one size up, I usually ride a 54 and will get a 56 with a 10mm longer stem.

Also I was speaking to a friend who is in the bike industry and he was saying Shimano is now making flat bar brake levers for road calipers. Also the road specific flat bar front shifter is different to the mountain left shifter apparently.

 

[JungleBiker]

I have contemplated the same issue before and decided I will use a road frame with flat bars.

I think for your case a 700c fork will be closer in diameter to a 26? with a 2? tire. It may still have a shorter crown to drop put length then say a short travel XC suspended fork however since it is essentially a road bike the steeper head angle is not going to be a problem and the lower BB will OK also.

One more question what rear wheels are you going to use? Don?t think Vs will be compatible with a 700c rim.

More on the V-lever (Shimano or Avids) and road brakes calliper, would the levers with leverage adjustment (eg speed dial) work any better?

I just did some rough calculations using the dimensions provided by Cloxxi and other sources and I reckon that (as you suggested) that a 700c fork and 700c wheel will not be too different from a 26 inch wheel with 2 inch tyres. I figure the front end (with road fork) would be lower by about 20mm. Just changing the 2 inch MTB tyres to 1 inch slicks would almost give a similar drop which I have already done and not noticed problems with geometry/steering, so we are not talking big differences.

As you say, there may be a change in head angle, but nothing major I guess.

I would put an Ultegra road brake on the 700c fork for the 700c rim. I'll look for a cantilever brake lever to try as pimpbot suggested.

I would just the leave the back end alone (with 26 inch wheel with 1 inch slick tyres and existing V-brake set up).

Thanks.

 

[Cloxxki]

The taller front wheel will partly correct for the more nervous steering of the steeper headtube angles. You should be okay, though verrrry racey. Illegal in UCI races even, where we sometimes saw small front wheels, so they now say front and rear must be the same. I expect your bike to look really cool, do post pics!
Tiagra offers a cheap lever for your needs, and Campa will come with very light ergothingies for 3x10, the left side should be nice for your project, that is if you're not running 1x9.

 

[jrm]

Im using full size V's and 700c rims

I have contemplated the same issue before and decided I will use a road frame with flat bars.

I think for your case a 700c fork will be closer in diameter to a 26” with a 2” tire. It may still have a shorter crown to drop put length then say a short travel XC suspended fork however since it is essentially a road bike the steeper head angle is not going to be a problem and the lower BB will OK also.

One more question what rear wheels are you going to use? Don’t think Vs will be compatible with a 700c rim.

More on the V-lever (Shimano or Avids) and road brakes calliper, would the levers with leverage adjustment (eg speed dial) work any better?

On my cross bike. If your using drop or dirt drop bars youll have to sue diacompe 287 levers. If your using a flat bar you can use any v lever including the speed dials. The V's are great with 700c rims IMO.

 

[jrm]

Different manufacturers use different TT lenghts

Isn't it hard to get a roadbike with suficient toptube for a flat bar? I know they're being sold stock like that by the thousands, Road/CX frame, CX fork, flatbar, but the upright shorter position might kill it, or...?

I rde a Curtlo 54cm frame with a 56cm TT. Most manufacturers use either the square diamond cinelli geometry which is 54cm with a 54cm TT or a variation like 54cm with a 55 or 56cm TT . Then theres also the compact design too. Again it depends on the manufacturer.

 

[top_ring]

As others have said, you`re going to have a hard time...

making your brakes work as effectively as your MTB brakes do if you mount a road caliper.
Actually, not all road calipers will fit your MTB wheel. You`ll need longer brake arms.

Might I suggest running a disc up front. This might defeat your purpose with the weight issue but for effective braking you can run a "Stiffster" CX fork from Soul cycles (690g) with disc mount and removable canti pivots... http://www.ridesoul.com .

I own one - and find it strong and comfortable. Mine is 648g with 8.5" steer tube and canti studs removed. And the price was $95.00 shipped.