Geometry-corrected Rigid Fork for 26" MTB

[KelvinCyclist]

Hi there,

I have been rocking an old yet trusty 26" hard tail CX MTB, with post mount disc brakes, for ages. Converting it to urban use on mostly tarmac lately. A semi-slick tyre at the back goes a long way giving it decent top speed.

Am thinking of replacing the 2.4kg heavy suspension fork to reduce weight for more speed (or paddling leisure) with a rigid carbon fork. I lock the suspension anyway when on tarmac. Need some advice here PLEASE.

Existing fork has supposedly 100mm travel with about 485mm crow-to-axle distance when unladen....bike standing on own weight without me sitting on it. When I do sit on it with usual water bottle and backpack, the fork sags by only about 20mm when standing still. Guess I am a light rider. This translates into an effective c-t-a distance of 465mm when ridding.

When shopping for a new fork, I found a 26" rigid fork "geometry corrected" to replace 100mm travel suspension fork but it has only 445mm c-to-a distance. I appreciate the "geometry correction" is by nature a generalization, using average value for rider's weight. Does it not mean I should be true to my own weight and measurement and pick a rigid fork with about 465mm c-t-a distance instead even when it is marketed for 27.5" or 29" wheel? Closest to original real life geometry?

I intend to keep my 26" front wheel with 160mm rotor by the way. Am I right to assume I can mount my 26" wheel to a 27.5" or 29" fork in that, c-t-a distance aside, the PS brake mount position should be the same and will accept my old wheel?

Many thanks.

Kelvin the fellow cyclist

[baabaa]

....and then add in 1 inch or 1/8th straight steerer, carbon or aluminium steerer tube, quick release, getting close to the right fork offset then your required to your axle to crown and with changing bike specs like trru axles you start to get very, very limited in your options.
Thinking a carver fork from bikeman? Good company and service - bought bits from them in the past but thinking shipping to Au will now be big $$ - suggest you send bikeman in Maine your questions
http://carverbikes.com/parts/forks/xc-460-classic/

On-one made a rather fancy carbon fork but you could pick 29er or 26 inch ( in the pre 27.5 in days) but good luck finding one now
I would forget about the weight and just go a simple steel fork close enough to what you have say from sury like a 1x1 and just ride your bike

[Nobody]

https://www.somafab.com/archives/produc ... canti-fork

[trailgumby]

If it's an old bike (and it's been a good 10 years since 26er XC hardtails were being widely sold) then a carbon geometry-corrected fork might be overcapitalising.

Are you riding primarily for fitness? If so, having been down the full weight-weenie path myself, I'm going to be a bit radical here and suggest you leave everything as is. Let me tell you why with a story.

At one point I managed to get my Cannondale Scalpel 29r down to about 10kg in race trim. Light bars, hand built carbon wheelset with CX-ray bladed spokes, light rotors, hubs and cassette, carbon seatpost and carbon-railed saddle, carbon cranks and XTR everything else. Dual suspension but lighter than most hardtails. It spun up to speed real fast and was a lot of fun to ride ... at the beginning.

What I found was that my fitness suffered. Heavier gear made me work harder in training. Using the lightweight bike meant that performance boost by subbing in lighter equipment on race day was no longer there, and I suffered a lot more in the race. Urrgh, that race was acutely uncomfortable.

So I took off the lightweight wheels. I built up a more robust training wheelset with some Stans Arch rims, put the heavy rotors and cassette back on and ran heavier tyres. I was slower initially on my usual segments, especially on the long steep climbs, but I adapted and got fitter. Next race, myself and a mate solidly podiumed in the pairs 50+ age category at the next Rocky Trail race we did at Wingello, to our disbelief and laughter (we worked our way up from the bottom of the results list and were convinced they'd missed our result).

So I still have the lightweight wheelset, but they only get fitted the night before the race. For training and regular riding I no longer obsess about bike weight - heavier is actually better (within limits). It's cheaper and more effective to burn the kilos off my middle.

[bychosis]

Will 20mm of height really make a lot of difference? I might be in the minority but find that little differences make little difference. I learn to ride the bike rather than rebuild the bike because it feels a bit off. Having said that, sometimes I’ve changed a bike to suit me better, but only if it feels really off.

[FairFrank55]

Hi there,

I have been rocking an old yet trusty 26" hard tail MTB(from this list), with post mount disc brakes, for ages. Converting it to urban use on mostly tarmac lately. A semi-slick tyre at the back goes a long way giving it decent top speed.

Am thinking of replacing the 2.4kg heavy suspension fork to reduce weight for more speed (or paddling leisure) with a rigid carbon fork. I lock the suspension anyway when on tarmac. Need some advice here PLEASE.

Existing fork has supposedly 100mm travel with about 485mm crow-to-axle distance when unladen....bike standing on own weight without me sitting on it. When I do sit on it with usual water bottle and backpack, the fork sags by only about 20mm when standing still. Guess I am a light rider. This translates into an effective c-t-a distance of 465mm when ridding.

When shopping for a new fork, I found a 26" rigid fork "geometry corrected" to replace 100mm travel suspension fork but it has only 445mm c-to-a distance. I appreciate the "geometry correction" is by nature a generalization, using average value for rider's weight. Does it not mean I should be true to my own weight and measurement and pick a rigid fork with about 465mm c-t-a distance instead even when it is marketed for 27.5" or 29" wheel? Closest to original real life geometry?

I intend to keep my 26" front wheel with 160mm rotor by the way. Am I right to assume I can mount my 26" wheel to a 27.5" or 29" fork in that, c-t-a distance aside, the PS brake mount position should be the same and will accept my old wheel?

Many thanks.

Kelvin the fellow cyclist

Hi. What did you choose finally? I'm not sure the height difference makes any sense as you said

[Bunged Knee]

OP had only one post and haven't been back from 24th Feb.

[KelvinCyclist]

OP had only one post and haven't been back from 24th Feb.

My bad totally, Bunged Knee. I was under the impression the forum will send me email notification when my post elicits any response. Did not get any notification. I thought my post was unanswered.

Kelvin

[KelvinCyclist]

....and then add in 1 inch or 1/8th straight steerer, carbon or aluminium steerer tube, quick release, getting close to the right fork offset then your required to your axle to crown and with changing bike specs like trru axles you start to get very, very limited in your options.
Thinking a carver fork from bikeman? Good company and service - bought bits from them in the past but thinking shipping to Au will now be big $$ - suggest you send bikeman in Maine your questions
http://carverbikes.com/parts/forks/xc-460-classic/

On-one made a rather fancy carbon fork but you could pick 29er or 26 inch ( in the pre 27.5 in days) but good luck finding one now
I would forget about the weight and just go a simple steel fork close enough to what you have say from sury like a 1x1 and just ride your bike

Thanks for the head-up, baabaa. The carverbike fork is out of stock at bikeman. In fact, the carverbike fork looks very similar to offerings from another brand called eXotic https://www.carboncycles.cc/index.php. On Bikeman's webpage about Carver fork, they said "the fork has been adopted by many different brands". eXotic also told me by email their forks were made in Taiwan. Think it is a classic case of a Taiwan OEM making by the large the same products for different brands. Not a bad thing as bike parts from Taiwan are typically of good quality. Chinese bike parts seem more like a hit-and-miss.

No luck hunting down anything from On-One though....much as you expected.

A Surly steel fork can indeed be back-up plan if carbon cannot be had.

[KelvinCyclist]

https://www.somafab.com/archives/produc ... canti-fork

Will bear this option in mind, mate. Thanks.

Kelvin

[KelvinCyclist]

Will 20mm of height really make a lot of difference? I might be in the minority but find that little differences make little difference. I learn to ride the bike rather than rebuild the bike because it feels a bit off. Having said that, sometimes I’ve changed a bike to suit me better, but only if it feels really off.

Good pt made, bychosis. Obsession over 20mm difference aside, I confess the main reason to prefer a longer c-t-a distance is it translates into forks made for 27.5 or 29 inch wheels. These are more widely available than forks made and marketed for 26 wheels for obvious reason.

Kelvin

[KelvinCyclist]

If it's an old bike (and it's been a good 10 years since 26er XC hardtails were being widely sold) then a carbon geometry-corrected fork might be overcapitalising.

Are you riding primarily for fitness? If so, having been down the full weight-weenie path myself, I'm going to be a bit radical here and suggest you leave everything as is. Let me tell you why with a story.

At one point I managed to get my Cannondale Scalpel 29r down to about 10kg in race trim. Light bars, hand built carbon wheelset with CX-ray bladed spokes, light rotors, hubs and cassette, carbon seatpost and carbon-railed saddle, carbon cranks and XTR everything else. Dual suspension but lighter than most hardtails. It spun up to speed real fast and was a lot of fun to ride ... at the beginning.

What I found was that my fitness suffered. Heavier gear made me work harder in training. Using the lightweight bike meant that performance boost by subbing in lighter equipment on race day was no longer there, and I suffered a lot more in the race. Urrgh, that race was acutely uncomfortable.

So I took off the lightweight wheels. I built up a more robust training wheelset with some Stans Arch rims, put the heavy rotors and cassette back on and ran heavier tyres. I was slower initially on my usual segments, especially on the long steep climbs, but I adapted and got fitter. Next race, myself and a mate solidly podiumed in the pairs 50+ age category at the next Rocky Trail race we did at Wingello, to our disbelief and laughter (we worked our way up from the bottom of the results list and were convinced they'd missed our result).

So I still have the lightweight wheelset, but they only get fitted the night before the race. For training and regular riding I no longer obsess about bike weight - heavier is actually better (within limits). It's cheaper and more effective to burn the kilos off my middle.

Big thanks, trailgumby, for sharing your insight and what you went through.

You are right about overcapitalising on an old bike. With that said, I bought my trusty hard tail at bargain bin price (like 1/4 of original) from a big local bike shop specializing in MTBs because they were clearing out stocks to expand its workshop space. So this bike gave me tremendous pleasure at not much more than what people pay for 1st bikes for their kids. All Shimano parts and hydraulic disc brakes though. So there is some sentimental value there. Surely I won't invest in a fork from say Niner, Enve or Lauf but there seems to be some bargain to be had from lesser known brands from time to time.

Yes, I ride mostly for fitness. Need cardio for at least 45 mins twice a week to keep my glucose level at bay. I can totally understand why you transitioned from weight-weenie to heavier training bike rider. My bike is a little over 15kg though including the junk in my saddle bag.....before phone on stem and water bottle. I do quite a bit of climbing too as there is no shortage of hill climb where I live. Shedding some 2kg by just fork replacement hopefully will help protecting my knees from over-stressing and allowing me to ride for more years to come. Me also into the 50+ category....well into actually. LOL.....

On a separate note, I kept the cheap but sturdy 3x power chain because of the hill climb. Loving the ability to drop to granny gear at front at flip of a button even when the chain is stretched.

Envy you on your experience over that Wingello race. THAT sounds like what biking is about. Glad you enjoyed it and importantly with a mate. Happy biking.

Kelvin

[KelvinCyclist]

Hi there,

I have been rocking an old yet trusty 26" hard tail MTB(from this list), with post mount disc brakes, for ages. Converting it to urban use on mostly tarmac lately. A semi-slick tyre at the back goes a long way giving it decent top speed.

Am thinking of replacing the 2.4kg heavy suspension fork to reduce weight for more speed (or paddling leisure) with a rigid carbon fork. I lock the suspension anyway when on tarmac. Need some advice here PLEASE.

Existing fork has supposedly 100mm travel with about 485mm crow-to-axle distance when unladen....bike standing on own weight without me sitting on it. When I do sit on it with usual water bottle and backpack, the fork sags by only about 20mm when standing still. Guess I am a light rider. This translates into an effective c-t-a distance of 465mm when ridding.

When shopping for a new fork, I found a 26" rigid fork "geometry corrected" to replace 100mm travel suspension fork but it has only 445mm c-to-a distance. I appreciate the "geometry correction" is by nature a generalization, using average value for rider's weight. Does it not mean I should be true to my own weight and measurement and pick a rigid fork with about 465mm c-t-a distance instead even when it is marketed for 27.5" or 29" wheel? Closest to original real life geometry?

I intend to keep my 26" front wheel with 160mm rotor by the way. Am I right to assume I can mount my 26" wheel to a 27.5" or 29" fork in that, c-t-a distance aside, the PS brake mount position should be the same and will accept my old wheel?

Many thanks.

Kelvin the fellow cyclist

Hi. What did you choose finally? I'm not sure the height difference makes any sense as you said

I have not made the choice, FF55. Been distracted by other exigencies of life outside of biking last few months.

It seems from the wealth of insights from fellow bikers the 20mm difference may not make a huge difference. With that said, I guess I will try to hunt for a sensibly-priced 465mm c-t-a carbon fork even if marketed for 27.5 or 29 wheels. Should be alright putting my 26 wheel on although the larger-than-usual gap above the wheel may look a bit strange. But hey DH bikes got comically huge gap there too because of insane fork travel distance.

Kelvin

[Bunged Knee]

OP had only one post and haven't been back from 24th Feb.

My bad totally, Bunged Knee. I was under the impression the forum will send me email notification when my post elicits any response. Did not get any notification. I thought my post was unanswered.

Kelvin

, No probs.

If you want your post notified, then click on it as shown below to let you know that someone had posted a reply to your email.

[KelvinCyclist]

OP had only one post and haven't been back from 24th Feb.

My bad totally, Bunged Knee. I was under the impression the forum will send me email notification when my post elicits any response. Did not get any notification. I thought my post was unanswered.

Kelvin

, No probs.

If you want your post notified, then click on it as shown below to let you know that someone had posted a reply to your email.

Thanks, mate.

[KelvinCyclist]

By way of update, I shortlisted two possible carbon rigid forks with a-t-c distance within 470 to 480mm range. Both marketed for 29" wheels. So the geometry (in terms of a-t-c length) should not be too far off from existing fork but the new problem is on offset.

One fork (QR) comes with 44mm offset whilst with the other (thru-axle) 51mm. To put things into perspective, existing fork (also QR) has only 40mm offset which I understand was standard for good old 26" bikes.

I prefer the thru-axle fork (even when it requires new front wheel) but fear a big jump from 40 to 51mm offset on 26" wheel and frame designed for it will make steering way too agile/sensitive for tarmac cruising.

Any view?

I read that 51mm offset (G2 geometry) was first devised by Gary Fisher to combat reluctance to steer with initial generation of 29" bikes by reducing "trail". It has since become not as essential with change in geometry of modern frames, resulting into modern 29" forks sliding back to 44mm offset.

FWIW, I fancy a switch to thru-axle for front wheel because I take out front wheel after each ride and, on reinstallation, slightly different QR skewer tension translates into brake disc rub 9 out of 10. What an annoyance!

[bychosis]

FWIW, I fancy a switch to thru-axle for front wheel because I take out front wheel after each ride and, on reinstallation, slightly different QR skewer tension translates into brake disc rub 9 out of 10. What an annoyance!

I’ve been using QR and discs for years and not had any noticeable issues with disc rub despite fitting and removing front wheels from multiple different bikes plenty of times.