brooklyn_bike

i’m considering swapping fork on 1993 XO-2 to a MTB crowned fork (non-unicrown) to get wider tire clearance

question 1) anyone with experience swapping forks feel free to weigh in on any obvious changes in ride quality / handling ?

question 2) did they mostly stop making 26” crowned fork MTBs with a taller steerer tube by the mid-80s? looks like they switched to more compact frame sizes at some point

XO2 is 59cm seattube with a longish steerer tube . measured from Crown Race to Locknut is 240mm = 9.45” Steerer Tube length including threaded portion at top

the head tube angle stays the same. the rake could be different and fork would be wider but i’m not sure the width would effect things much ?

examples of nice vintage forks but short steerer tubes

Piff 

That's really tall...

The only fork I can think of that is tall enough is a modern Dimension fork, 1" and threadless. 260mm, might just barely be long enough.

Another option is buying a nice older fork and getting a framebuilder to replace the steerer with a new, longer steerer. $$$$$

One final option is to add some clearance to the original fork using a vise and a wooden form. But....I know there has been some discussion over whether or not that's actually a good idea to do to fork blades. Can't remember if there was any resolution?


Oh yeah, and rake/trail issues. Yes, you will have problems potentially. I've never looked at frame geometry numbers for the XO series of bikes, but I wouldn't be surprised if the head tube angle, rake, and axle-to-crown length are all different compared to the usual expected numbers for contemporary 26" mountain bikes that came with a 1" threaded fork.

Bianchigirll 

brooklyn_bike Isn't a X)-2 more like a hybrid or city bike than a mountain bike?

I believe the the change in fork crowns was more economic than anything else. I don't think compact frames were a thing just them.

Your tire clearance might be more an issue of tarrif than anything else. There was limit or something on tires size in the late '80s to protect the American mountain industry, but other than Cannondale and Trek I don't think there were a lot fo "bread and Butter" level MTBs being built in the US.

I'm not sure where to look for it, but swapping to a more MTB fork on that OX2 you might want to look closely at the trail, the axle to crown length might be something to check too. Between the two it might effect handling a bit.

Korina

How big are you looking to go with the tires and what are you looking to do with the bike? In the illustration the bike appears to have room for wider tires,

It's nice to know that someone made my perfect bike (street frame with 26" wheels). I'll assume that it doesn't exist in my size and not go on a wild goose chase. {le sigh}

brooklyn_bike

there are MTB forks from 1980-1985 built for 58cm frames i'll need to keep an eye out for an orphaned fork or frame

i posted on BF and several other Bike Frame Builder threads : i'd say 90% said it's a bad idea. the other 5-10% had tried crimped forks and thought it was an ok solution. i decided to just source a new wider fork and keep the original unchanged


the headtube angle will stay the same. the rake could be different and axle to crown length could be different but prob not by much

brooklyn_bike

yes when i research bike catalogs from 1980s at some point all the major manufacturers stop making MTBs with crowned forks and stop making bigger MTB frames (58cm - 60cm) i.e bridgestone / miyata / trek / fuji / specialized / schwinn

i've seen articles where overseas bike manufacturers try to skirt tariff laws on 26" wheeled bikes : the schwinn frontier with 650b wheels was an example but the Bridgestone XO-2 wasn't specced to avoid tariffs - grant peterson made the first attempts to take basic road bike frame geometry but with 26" MTB wheels for a terrific all-arounder mixed terrain bike

i'll prob just try a fork or two as i run across them and see how they ride - there's a lot of variables at play so it's prob difficult to predict until i take it for a ride

Piff 

Finding a high quality fork that matches your frame geometry well and isn't tweaked after all these years...it's going to take a while.

What I meant by headtube angle is that a fork made for a 68 degree headtube will be very different than one made for a 72 degree angle fork. I'm assuming here, but I would bet that the XO2 has a steeper headtube than mountain bikes of that era. You're going to have to some measuring and math to figure out if a replacement fork will play nicely. I, again, have doubts since the XO bikes are most definitely not mountain bikes. If I were in your shoes I'd go custom or resign myself to a smaller tire width. Good luck with the hunt if you do decide to go that route!

brooklyn_bike

the 1993 XO-2 accepts 1.9 tires . i'm using Compass Naches Pass 1.8" and have used paselas 1.75 and avocet fas grip 1.9. i'd like to get a slightly wider fork that allows for the next size bigger 26" tires : Rat Traps 2.3, GravelKing 2.1, Ultradynamico 2.2

what size bike frame do you ride? the XO-2s are also my ideal bicycle. i had to sell all of my bikes before moving across the ocean and i only kept my XO2 my wife's XO2 and my 3Rensho racer. the XO2s came in five (5) frame sizes from 42cm - 59cm. they are fantastic all arounders : commuting / touring / hauling / gravel / road / and you can go pretty damn fast on them too

brooklyn_bike

larger MTB frames from early to mid 1980s (58cm - 60cm) i.e bridgestone / miyata / trek / fuji / specialized / schwinn should have a long enough fork steerer i'll just keep an eye out for an orphaned fork or possibly an entire bike or frameset to use for parts. some examples :

70sSanO

If you can find a Kona Project 2 fork with a 1” steerer, that would probably work. I think they made threaded but I don’t know the steerer length. I know they made a threadless and the steerer is 11-1/2” tall.

You’ll need to find an uncut one. They were available up until 10 years ago.

John

brooklyn_bike

i just looked those up : i think they're unicrown tho

brooklyn_bike

i can take my time the bike rides great as is . it's more of an experiment and to increase the versatility of having just one or two bikes instead of a big bike stable like i used to have. the bridgestone XO-2 in my frame size that year is 73º HT and 73º ST angles more upright than the slacker 1980s MTBs. but i'll prob just try a fork or two as i run across them and see how they ride - there's a lot of variables at play so it's prob difficult to predict until i take it for a ride

t2p

just a note on the Naches Pass 1.8

Naches Pass endurance casing barely measure 1.6 mm installed (on Campy Mirox rims)

brooklyn_bike

yes that's right. this is another problem trying out expensive tires and getting the right max size dialed in - the actual tire width varies quite a bit. i have them same measurement : 1.6" on very wide araya rims. i was able to squeeze 2.3″ RatTraps onto this bike frame but it was super tight on the fork (1-2mm of clearance) and 2.3″ RatTraps actually measured out to 1.95" on my rims

Bianchigirll 

brooklyn_bike I didn't realize you were in South Korea and that pretty much invalidates everything I said

brooklyn_bike

no worries ! i just recently moved from PDX to Seoul. i had quite a big bike collection and bike parts stash just a few months ago.

Piff 

If you're lucky the axle-to-crown will be longer on the replacement fork. Combined with large, knobby tires, the front end may end up 1 degree slacker as a result. I think best case scenario you end up with trail in the low 50s, but it's very possible your replacement fork dips you below that into the 40s.

t2p

darn

also have a pair of Naches Pass extralight casing - got them from LBS (new take off)

passed on the Rat Traps (before I realized the tires ran small)

t2p

btw - Maxxis DTH 2.15 and 2.3 might also be good options

(and Schwalbe Billy Bonkers)

70sSanO

Don’t know how I missed “non-unicrown” in the beginning of your post.

John

brooklyn_bike

thank you Piff ! this is excellent and the type of info i was looking for : catalog says 1993 XO-2 stock has 56.6 trail so i'll be happy with trail anywhere in the 50s

brooklyn_bike

yes i've def looked in to Billy Bonkers for the rear wheel of my Bullitt cargo bike - they got mixed reviews tho . i'll check out Maxxis DTH i'll need to see how much shipping is for certain tires now that i'm in asia. i know panaracer tires cost less over here some euro tires are about the same and stuff from US is a bit more

i used to buy used tires for cheap from bike swaps / bike co-ops in PDX : it let me try them out with low risk and if liked them i'd keep an eye out for a new or slightly used set. luckily i found several sets of compass tires in various sizes to try out for cheap

Korina

At 5' 4" I'm in the 17 - 18 inch/48cm range. I love my '90s mtbs but the long top tubes cause issues with my short arms.
ETA: I did look on eBay, and someone does have an XO-2 frame in my size for $150. No fork, just the frame. $150.

brooklyn_bike

yep that era MTBs it was the fashion to have a long toptube and short stem. the 1994 MB-1 my partner and i used to share (they're 5-5" and i'm 6') the seattube was their size (49) and toptube was my size (57.5) looking at the catalog scans - they had a lot of seatpost showing - i think to give more clearance for the bike rider from the toptube

if you ever get a chance to try out an XO-1 or XO-2 if you happen to find for a good price - give it a try. the toptube is less long and in proportion to the seattube. it's my partners favorite bike from all the bikes i've built up . it's got the 26" wheels of an MTB and road geometry so it rides and climbs really nice

brooklyn_bike

heh if you buy it you'd be in the same boat as me : XO-2 in search of fork. XO-2s especially do show up at good deals at times. i found both of ours on craigslist for $100.00 - 150.00 for complete bikes. XO-1s are always insanely expensive.