Converting the 26" hardtail to 'modern' gravel

[Fatal Swan]

So, I'm in the middle of repurposing the old 26" hardtail for winter road and maybe 'gravel' use (though I hate that term). I've been thinking through a few options for using up frames and parts that I have left over in light of what kind of bike I might actually use. I have a modernish superlight carbon road bike that I use all the time for 5-6 months of the year, a full-sus XC bike for the increasingly rare occasions that I'm in the mood for that, and another one old bike set up on the turbo. A winter road/gravel bike with drop bars hydraulic disc brakes seems like something I might be able to actually use - I've set it up lately for road use with flat bars and V-brakes and it's not getting much use: while it's fast, I'm not keen on flat bars on the road and am just not likely to choose it ahead of the road bike: viewtopic.php?f=21&t=249295&start=60

Most of the potential obstacles of the drop bar conversion are overcome, I think. I've matched up the dimensions to my road bike and to my surprise it looks like like I can match the key dimensions more or less exactly without any real trouble. Wheels-wise, the frame and fork could probably accommodate 700c wheels with tyres up to about 35mm, but I've already got decent 26" disc wheels and good slick/semi-slick tyres that in principle I could swap out for different kinds of use. I wanted to go to hydraulic discs for the winter and I have 2 x 11 Ultregra hydro STIs on the way with post mount calipers that should fit my IS mounts on the frame and forks, with adapters (unlike nearly all of the new flat mount road brakes). I've got chainstay clearance for at least a compact 50t chainset, which is what I run on the road bike anyway.

My last theoretical hurdle (or maybe just my current one until I realise what the next one is) is the cassette. Going with the 11 speed Ultegra STIs (which I needed to for hydro discs) means I need to shoehorn an 11 speed cassette onto my Shimano MTB freehub. 11-speed MTB cassettes seem to be no use as they're designed for 1x11 (and the gear ratios would be mad with a double chainset) but 11-speed Shimano road cassettes won't work either since they're too wide. However, I believe the widest ratio 11-34 Ultegra cassette (maybe the 105 too?) was designed to be able to fit 8/9/10-speed road freehubs too, so I'm hoping that's going to mean it'll fit the standard MTB freehub as well.

The alternative is to fit 700c wheels, though the options for 135mm rear disc wheels for QR axles seem to be getting limited with the modern thru-axle trend on road bikes, certainly for anything nice and light.

What else am I forgetting?! I'm planning to bring the build in at about 8kg all-in, and when I've got many of the required parts for that already (frameset, stem, post, saddle wheels, chainset) compared to the cost of getting hold of an 8kg gravel bike with hydraulic discs it should be worth my while giving the conversion a try!

 

[ishaw]

Re:

Ive been mulling over something similar, you have overcome the biggest and high budget issue imho which is hydro road brakes/shifters (I'dove to find a cheap option). The wheels aren't as challenging as you might think. A set of 29er wheels with rear qr aren't that hard to find, or convert from bolt through to qr. I've used bolt through to qr inserts on some wheels in the past, simply to use a frame with a qr drop outs but more modern wheels. Ive tended to go for oem adapters but there are various options online from inserts that slot into the bolt through axle, to a full axle replacement or full length insert. I've only used the oem adapters myself (mavic or fsa in my case).

 

[Fatal Swan]

Yes I've really been back and forth with the options on this one - wheel sizes, brake types (the frame can take rim brakes), gearing/STI options etc. After I settled on a hydro brakes requirement brakes, it ended up almost finishing off the whole thing since it really restricts the gearing options to 2 x 11 Shimano (the SRAM options all seem to be flat mount which cant be adapted to fit an IS frame, I understand).

I was pretty close to the Tektro cable-actuated hydro calipers since I could have taken my pick with STIs then, but I ended up finding a new set of Ultegra levers ready-fitted with post mount RS785s for just over from £200 overseas (taking my chances on the import duties, but I'm ready for it if and when that happens!).

I figure I can fit 26'' wheels for now at least as I've got a set of 1400g Rovals as well as the tyres, plus and it'll give me the option of fatter/gravel tyres with enough frame clearance should I need them. I think I'll see how that goes first, though I have been looking at the Cero ARD23s at around 1500g for £300.

 

[hamster]

If road cassettes won't fit then you could break the road cassette and use a '10 from 11' setup with a spacer or two at the back. It's a common compromise for putting 8/9/10 on a 7s body. It's probably no loss to ditch the 11T top gear anyway. Often the second sprocket also has lockring teeth.

 

[Fatal Swan]

If road cassettes won't fit then you could break the road cassette and use a '10 from 11' setup with a spacer or two at the back. It's a common compromise for putting 8/9/10 on a 7s body. It's probably no loss to ditch the 11T top gear anyway. Often the second sprocket also has lockring teeth.

Hmm, now that's something I hadn't thought of. The main thing that concerns me about having to go with the 11-34 cassette, if that's my only option, is the bunch of additional wasted weight (even the Ultegra is 337g!) on an unnecessary sprocket - I really don't think I'd miss the 34x34 on a 26" wheel bike being used on the road.

Now the 11-speed 11-30 Ultegra cassette for example is 11-12-13-14-15-17-19-21-24-27-30 and the smallest 6 are all separate sprockets. I'd probably prefer to keep the 11t with a compact 50/34 chainset but I could still knock out the 14T, say, which would give 11-12-13-15-17-19-21-24-27-30. And even losing a gear overall, I'd gain an extra one at the bottom end (since the 11-34 is 11-13-15-17-19-21-23-25-27-30-34).

There's about 70g to be saved in the cassette then, plus a bit more on the rear mech, since the short cage Ultegra will do 11-30 whereas the 11-34 needs a long cage.

Food for thought... Cheers!

 

[hamster]

Even on gravel I find 34 front 28 back to be more than I need so I agree 34-34 is probably overkill.

Removing the 14T from the cassette looks an elegant solution I hadn't considered.

 

[Fatal Swan]

Oh, and sneaking a short cage rear mech on with the 11-30 cassette means I should be able to use a DA rather than Ultegra, that'll be another 50g off

 

[legrandefromage]

Why dont you change the freehub body on the wheels?

Heres a rather smart conversion: viewtopic.php?f=6&t=408436&hilit=gravel+saracen

 

[PaulE]

It's possible, and relatively simple give the skill and kit, to skim the difference between the cassette widths from the back of an 11 speed road cassette on a lathe. I've done it a couple of times, and it only took about 5 minutes.

Obviously depends on having access to a lathe or someone with one thought, but then you get all 11 gears. If you happen to be in Sheffield then I can probably sort it for you.

 

[M_Chavez]

Re:

I've done something similar (see my old frankengravel thread). I'd keep 26" wheels - personally I really don't like 29ers. On the road there's bugger all difference and on the trail 26" are a lot more fun imho.

The conversion was great fun, however, I've rather quickly murdered my 20-year-old front suspension fork (needs a full, overhaul now) and I needed a bike that would take a pannier rack for a child seat, so I've re-built the "gravel" on a cx frame instead.

Don't know much about hydraulics, but if you're not married to them, you can get a "road" version of BB7 that works well with cable brifters. And then you're not married to an 11-speed cassette and can go for an honest man's 3x9.