I’m in the process of converting a heavy Trek Roscoe MTB into a lighter commuting bike for my daughter (she insists on a MTB, as she prefers the bar shape vs curly or commuter style bikes). I’ve already replaced the 27.5 x 3.0 mid-fat wheels & tyres with an old set of 29” Hunt XC wheels (clearance for the fork is borderline but OK, frame is fine), which dropped 1.6 kg of weight.
My next step is to replace the Suntour “suspension” fork with a rigid one. The current one is mostly steel and feels awful - I can’t compress it more than 30% with all my weight on the “lightest” setting. For commuting, 29” tyres are all the suspension she’ll need.
My problems is the Trek Roscoe uses a Boost fork but has a straight steerer tube and those 2 combinations are unusual (e.g., it’s hard to find a rigid replacement). As I said above I’ve already swapped 29” wheels in and they are Boost, so would like to keep them as they’re nice and light. I can find Boost tapered rigid forks, however.
The frame looks like it could accept a tapered fork (head tubes is very tapered), so checking with the brains trust here, if that guess is correct.
Below is a photo, where you can see an over-sized bottom bearing race. I’m guessing the fork is just using a larger diameter crown race, to allow the straight steerer to be used in this model (and that other higher-end variants do come with a tapered steerer fork).
Replacing the headset more than just nice to - It will be a requirement - as it’s unlikely you’d find a crown race for the replacement fork with tapered steerer that would match that existing headset. Much easier to get a full low cost cartridge bearing headset instead and replace the whole lot including the cups in the frame.
Great suggestions on the replacing the 2 x bearing races with sealed cartridges.
That lower bearing race looks like it interfaces with the black upper cup in the photo. I presume I’ll need to remove that too. Will the cartridge bearing just fit up in there or will it require an extra bit of hardware? I’m thinking it won’t but not sure TBH.
100% you’ll need to replace the headset cups in the frame. No chance sealed bearing will interface with the ones currently in there.
You absolutely should use the correct tools for that, if at all possible, but can be done with careful use of a hammer. Use with a punch (or large screwdriver) to remove, and then use with a piece of wood to drift in the new ones.
However, getting the right headset can be a minefield, so would strongly advise taking frame and new fork to good local store/mechanic and just get them to do it all. Headset should be 20-30 £/€/$ (no need to go higher, and if cartridge, cheaper likely also ok but probably won’t find cheaper in a store) plus 15-20 mins workshop time.
Roscoe’s are definitely a tapered head tube and you are right the higher end models come with tapered forks, semi integrated headset and cartridge bearings. Just a case of finding out what fits.
You may know this, but that era frame was also used on the xcaliber as a 29er with 100mm fork. Sharing noting you are looking at different fork options, may give insight to potential geo changes.
Thanks for those suggestions. I think I will try my LBS as I’ve hit the dreaded headset bearing hunt in the past and they came through with the goods. I do have access to proper tools curtesy of a couple of riding buddies who have extensive tool collections but finding the right parts will be the tricky part, as suggested.
Considering the complexity and added expenses, I’m starting to have second thoughts on the fork upgrade, or at least might delay it a bit. We live at the top of a gentle hill and coming home up that hill is the thing I’m trying to “lessen”, so my daughter is more inclined to ride more. But it’s a marginal improvement and we all know aero trumps weight (haha). I’ve massively improved rolling resistance by getting rid of those 3.0" tyres, so that might be enough along with the 1.6kg savings.
