MotoBacone

I bought a 2005 Redline Conquest Disc-R frame and need help selecting a fork. I'd like to put a suspension fork on it but I'm not sure what size fork I need for the bike. What measurements do I need to consider for the fork? How can I make sure the fork I get is the right length?
Also if anyone owns this bike would you be willing to provide measurements of the fork that's on your bike?

I can't post links yet but if you Google "2005 redline performance catalog" the catalog for my frame with measurements will be the first result.

chas58

I would want to know: the rake, Crown Height (axle to crown), weight, Steerer length, maximum tire size.

Catalog is here but it doesn't say much: https://issuu.com/redlinebicycles/docs/05rladultcatalog
other than the fork offset is 4.5, which is pretty standard.

MotoBacone

So how should I determine what sizes would fit my frame for those measurements?

unterhausen

That bike is not going to work well with any suspension fork I know of. It probably has a 1 1/8" steerer, which makes it possible to put a suspension fork in it, but the head angle is going to be very slack. The catalog doesn't list the axle-crown length (A-C), and I can't find it on the internet. It's probably 385-395 or thereabouts. They do list the rake as 45mm, which is the least important measurement.

DorkDisk

Suspension is a hard match, some more a-c length is to be expected. This type is the closest I know that will fit; dunno how it rides as its meant for city riding. Other than that, vintage Ruby.

msu2001la

As other have indicated, there is no such thing as a suspension fork that will be an exact fit for this bike. Any fork with the same size steerer (1 1/8"?) will "fit" in the sense that it can be installed, but it'll be longer than a rigid fork to accommodate the travel. How much longer depends on how much travel the fork has. These days, I think 29er forks start at 100mm. You might find something older that is 80mm? There also might be some short travel hybrid bike style suspension forks designed for on-road riding that could work, though I don't really see the point of that.

Adding a longer fork will raise up the front end of the bike and change the way it handles. The more travel, the higher the front end will be. You can try to offset this by using a negative rise stem, but consider that a 100mm fork would add over 4" to the height of the front end, so even a super slammed stem setup would probably feel way too high.

Are you building something for a specific scenario? I'm curious to know what the max tire size is on the rear. Seems like it would be limited to 33m cyclocross tires, which would limit off-road riding scenarios where a suspension fork would be beneficial.

unterhausen

I think I would try a suspension stem.

joejack951

No personal experience with these forks, but they were brought to my attention by someone looking for one of my 15 to 12mm axle conversion kits. Probably the cheapest short travel, straight steerer suspension fork you’ll find: https://www.ebay.com/itm/SR-SUNTOUR-...53.m1438.l2649

I mention short travel because it’s going to have the least impact on your bike’s geometry at only 50mm of travel. Probably something you’ll notice at first but forget about after a few rides. You may need to re-level your saddle though.

unterhausen

That's an interesting fork, 430 A-C, so sagged would be less than 420mm. If his current fork is 395, then that's not going to be too awful. More trail, more flop. Some people like more trail on a gravel bike

chas58

I had a friend put a new suspension fork on an old frame. It handled horribly, just horrid. Because the oldschool short travel forks were not available any more he had probably added 20mm to the fork lenght. I never want to ride that bike again.

Moral of the story - stick to the original specs or darn close to it. If the bike wasn't designed for suspension, start over with a different frame, or just use a redshift (suspension) stem and softer tubeless tires.

MotoBacone

I ended up finding a Suntour suspension fork on ebay with 30mm of travel. It came with some strange large headset so we'll see if it works. Sizing-wise though it seems that the front is lifted up a bit higher but it might be workable. I'll update when I finish the build.

fietsbob

None of the Conquest cross bikes a have frame geometry suitable for raising the head tube , thereby altering the geometry negatively

What you want is a hybrid like Trek's Dual Sport made to have a suspension fork and good steering geometry/ handling, when built up..

then convert it to drop bars if you want..