bikerider7

I have a vintage Orbea Lobular bike frame, which I am building up. I have only the frame, not the fork. I don't know what fork it originally had, so not sure how to select a fork with correct rake/offset. I brought the frame to a bike shop for their advice, but they could not say.

I did find some old reviews of the bike on the web -- which said it had an Easton EC90X fork. That fork has 45mm offset, so I could perhaps just go with that (the Ritchey CX Comp fork has the same offset). However, I don't know if Orbea changed the bike year-to-year...

Any other suggestions?

Rolla

Wild idea, but have you asked Orbea?

bikerider7

Yes I sent a message, but in my experience marketing and HR departments don't know answers to technical questions.

cxwrench

Offset is not the only parameter to pay attention to. Axle to crown (basically the length of the fork legs) is another.

bikerider7

Good point. I think the EC90x is 395 vs 400 with the Ritchey (seems close enough).

fishboat

Nearly any company with have a tech service dept or people selected to answer technical questions from their customers. You need to try just a little harder.

Rogerogeroge

Yep. CX forks have 395-400 mm ATC. Road bike standard is around 367 mm.

Camilo

Can't go wrong with Ritchey, of course. But, I always recommend looking at the Columbus lineup for aftermarket forks. They have a post-mount brake and disc option(s?) and might be worth looking at.

I've only had experience replacing a couple of forks, but I think I learned a lot, mostly by pestering these forums about it. Changes in rake and A-C length can affect handling separately. Combined they can affect it greater or might actually offset each other. There are online calculators which take these specs as input and can show how they affect things such as trail and effective head tube angle.

If there are changes, they may or may not be great enough to notice. If noticeable, they might be too negative to tolerate, or easily adapted to, or might actually feel better. This all depends on personal preferences of the rider. If you use one of those calculators, and ask folks how the changes you see might affect handling, you can get an idea.

My thoughts? If you get anywhere close, you won't notice anything bad, especially since you don't have a fork to compare the resulting handling to.

My personal experience is that one was not noticeable at all and the other was noticeable. That noticeable one, I didn't like at first - it made the handling feel twitchy, a little quicker, but after a couple of rides, it doesn't bother me at all, it's just a quicker handling bike than my others. It's still fun to ride and comfortable, just different and it's nice to have variety. Interestingly, with that bike, the replacement fork was very close to original, based on the old catalog geometry charts I saw online. My guess is that it was closer to OEM than the fork that was on the bike when I bought the frameset (which had a different replacement fork) and that the handling was just designed to be as it is now. And the bikes I compare it to are a relaxed Felt Z and a gravel bike, so there's that - they're on the other end of the spectrum, "stable" vs "quick".

flanso 

Perhaps you could measure some of your frame's dimensions and, if you can, angles (like the head tube.) Then surf for a bike frame with similar geometry and see what the fork spec are.

bikerider7

Thanks everyone for the suggestions. I located some brochures showing the geometry, and based on that I ordered a fork. Interestingly, the diagrams showed an offset of 50, whereas the EC90x has 45. I found another fork with 50mm offset.

The folks at Orbea did respond, and said: "we no longer have spare parts for this model, as production ended several years ago. There is no other compatible fork available." I guess when the fork arrives in mail I'll find out whether it is compatible or not....

Camilo

I would bet good money that since you found the same rake, any A-C length within a few mm will indeed be very satisfactory. Any change in handling from exactly the way that bike was designed would be unnoticeable. And since you have nothing to compare it to, it will be absolutely unnoticeable.

FWIW, I think that the fork rake used for bikes is somewhat arbitrary within small limits. As one example, I was building up a vintage-ish frame (90s). I found catalogues which showed every geometric spec for the frame and fork for the various frame sizes. In the year of my bike they used a 43mm rake in my frame size and 45 rake in the next larger sizes. The next year - for the same frame dimensions and geometries - they used forks with 45 rake for my size as well. Either they decided that the 43 rake fork didn't serve the smaller frame and 45 would be better, or they decided it made so little difference that it would be simpler just to stock 45mm rake forks for both. I used that rationale to buy a readily available 45 rake fork rather than a 43 which I couldn't find at the time. I wold guess that AC length within a small variation is also adjusted by the frame makers to reflect what is readily available, and variations within, say, less than 5mm (1/2 cm, 3/16") is not meaningful. THis is not to say that varying both small amounts mght have an effect, but one or the other, probably not.

As an editorial comment: that Orbea says there's "no other compatible fork available" is not good customer service. What they should respond with is simply giving you the dimensions of the original fork: AC length, rake, steer tube dimensions, etc., I guess it makes sense that they don't encourage you to buy a replacement fork from another source because they have no control over the quality of that fork and a person could go back at them if there is a problem and injury. But to simply give the specs of the original and maybe saying that there is no compatible fork available from Orbea is helpful, but saying there's no compatible fork available is just BS.