# Gravel bike from old MTB



## figbat (22 Dec 2019)

Below is a combined summary of a series of posts I made on another forum over the course of this project. I’ll post it in order as if it were happening now, but obviously you'll get the finale straight away.

My project.

Over time we have accumulated a number of bikes in our household. One of them was an old Trek 830 (circa 1997) which was picked up many years ago for around £20 for my wife to ride. Over time I moved up from a 26er alloy hardtail to a 29er c/fibre hardtail, so my wife got my 26er, making the Trek redundant. It has sat in the shed for years and moved house twice but never been ridden. So it is now my little project.

It's not worth much as a retro/vintage MTB, isn't especially rare or desirable but is a nicely-made cromoly steel frame in slightly scruffy but sound condition. Over the last few months I have been scrounging, finding and where necessary buying parts to turn it into a mongrel bike. I am aiming for a CX/gravel type of thing with drop bars.

Here is how it started:






And after this weekend, here's how it now stands:





First I stripped the frame of all components (except the bottom bracket, which is a very solid square taper running smooth and free, so I left it alone).

Then I punched out the threaded headset and pressed a 1 1/8" threadless headset into it - this was to open up options for a replacement fork; I had the headset already.

A friend I ride with donated a fork he happened to have lying about, which had disc brake tabs on; it'll need the steerer cutting down as you can see.

I had a spare stem and picked up some cheap 'bars from a cycling forum.

The alloy seatpost is from the original bike, topped with a Charge Spoon saddle also picked up from the cycling forum.

The wheels are 622x19c disc wheels, picked up from eBay - the biggest unknown I faced was whether I could fit 700c wheels with chunkyish tyres into the frame - they fit with room to spare. The Schwalbe CX Pro 30mm tyres came from a local selling group on Facebook.

That is how the rolling chassis now sits. Next I have to:

Fit the brakes - I have some TRP Spyre mechanical disc calipers from eBay but still no levers; I am after a 10-speed Shimano STI set and still looking. I'll also need an IS-to-post mount adaptor on the front and an A2Z disc brake adaptor for the rear (this is one thing I am uncertain on whether it'll work). I'll also need some compressionless cable housing.

I need a crankset - the one that came off it is three-ring but the rings are riveted onto the spider and the BCD doesn't match any common standards so I'm hunting for a cheap, square taper crankset for a single ring set-up.

I need a 10-speed cassette and chain. I have a derailleur to try out.

I need to set the stack height and cut the steerer tube.

I need to wrap the bars (I'm looking at red).

And then it is just finishing touches.

I know it won't win anything. I also know it'll end up being worth less than the parts I bought for it and may not even ride very well, but that isn't the point. It will be my bike, that I designed, with solutions to challenges unique to this bike. It is something to keep my mind and hands busy and so far has served that purpose well.

I'm in no rush - it has been over a year to get to this point (that is over a year of waiting, bidding, finding, researching and gathering and about 2 hours building this weekend). It may take another year to find the parts I want for the money I want to spend (ie very little). However, so far I am pretty pleased with how it is turning out.


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## figbat (22 Dec 2019)

Some small updates today:

- fitted a disc to the rear wheel; it clears the chain stay by a few mm, so all good there
- offered up the A2Z disc caliper adaptor; looks like it’ll work with a small amount of fettling
- fitted a road 10-speed cassette I had lying about, just until I can get a wider range one
- fitted some new crank arms with a narrow-wide 34t chain ring
- fitted the pedals off of the old MTB, just for somewhere to put my feet until I can get some SPDs
- fitted a XT derailleur
- added some spacers to the steerer; stack height feels good so I can cut the steerer I think
- offered up the front brake caliper; seems to line up ok with the disc.

To do:

- fit the front caliper; I thought I didn’t have any M5 bolts to fit them but it turns out the bolts from the old canti bosses fit perfectly, which I only realised after I had downed tools for the day
- fettle and fit the A2Z; it’ll need a little bit of trimming with a Dremel grinding tool to sit flush against the dropout
- acquire another IS to post adaptor to fit the rear caliper to the A2Z
- acquire and fit a cassette (looking for 11-36 ideally) and chain
- acquire and fit some shifters/levers and compressionless cabling
- wrap the bars.

With the cranks and pedals fitted I took it for a brief freewheel up and down the drive and across the road. In the very limited ‘ride’ it felt pretty goodn it rolled, balanced, steered and generally behaved like a bicycle should. I’ve never built a bike before, so can’t wait to actually ride it.


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## figbat (22 Dec 2019)

I have nearly everything to finish it now, just need time to get it together. I have some Tiagra 4600 levers, a 11-36t 10-speed cassette and chain, a cable set (in yellow ) and some red bar tape. I have to build it outside so need light and weather (and free time) to get on with it.


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## figbat (22 Dec 2019)

Bit more progress today, a couple of the bigger jobs done:

- modified and fitted the A2Z brake disc adaptor. It needed some metal shaving off to fit the dropout and frame neatly, but it’s on now and seems solid (no caliper mounted yet though)
- cut the steerer and mounted the fork properly
- mounted the front caliper
- mounted the brake levers/shifters
- cabled up the front brake, now fully working
- ran cables for the rear brake and derailleur
- fitted the wider range cassette.

To do:

- fit a chain, cable up the derailleur and index the gears; the chain I have did not accept the KMC quick link I had, so will need another option
- mount the rear caliper (still need an IS to post adaptor) and attach cable
- put the bar tape on
- test ride!


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## figbat (22 Dec 2019)

Finally - done! Mostly.






The indexing is still not right - I’m looking out for a Tiagra 4600 long cage rear mech - but I took it for a ride with the kids and other than the occasional skipped gear everything else worked as it should. I need to shake it down fully before I will trust it on a longer/faster/harder ride, but I’m pretty pleased with the outcome.


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## figbat (22 Dec 2019)

Update.

When I first conceived the project I was aiming to pass some time, have a project and hopefully build something that worked. There was a chance it would fall apart like a clown bike, or be a fatally flawed design, or just be ugly.

Having finished it and ridden it it is fast becoming my favourite bike. It’s not a beauty, but I still love looking at it. It’s not a lightweight, but I keep reaching for it when given the choice of a carbon fibre hardtail 29er, an alloy Synapse or a carbon fibre Fuji road bike. I have ridden it over a range of surfaces, from road to singletrack. I have climbed my worst local climbs and descended the best descents. It is not that much slower than a road bike on the road, despite the weight and 43mm tyres and handles some pretty rough off-road. So far nothing has fallen off or gone wrong and it rides really nicely. I’ve had one small off which it shrugged off with nothing more than marked bar tape.

When on the 29er I feel out of place any time I have to link up on the road. On the road bikes there’s little choice but to stay on-road. On the FrankenTrek it feels good everywhere and means I can link up road and track to make new routes. I made a bike and I like it.


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## Gunk (22 Dec 2019)

I really like that, great project and really nicely done. How is the gearing for the road? That’s a very small front chain ring.


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## figbat (22 Dec 2019)

I geared it for climbing - you’re right, it spins out on the road. A future upgrade will be a longer chainring and wider range cassette.


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## roadrash (22 Dec 2019)

great job , I like that ….a lot


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## All uphill (22 Dec 2019)

There's nothing like a bike you have built yourself!

I love knowing every nut and bolt,every choice and compromise made.

😃


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## DCLane (22 Dec 2019)

Nice project; a re-used old bike that's no longer just sat in a shed taking up space.


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## videoman (22 Dec 2019)

Great build and good to see you enjoy riding it so much. I'm doing the same with an old 1990's Giant Granite steel framed mountain bike which has been put out for the scrap man once but I could not let it go.


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## the snail (22 Dec 2019)

figbat said:


> The indexing is still not right - I’m looking out for a Tiagra 4600 long cage rear mech


looks like you've already got the medium cage rd on there. If that isn't enough, I think you could try a derailleur hanger extension, or If you want an actual long-cage rd, a 9 speed mtb derailleur should work? Also worth making sure the b-screw adjustment is good. Nice job though - those old mtbs are certainly versatile bikes.


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## figbat (22 Dec 2019)

I think I have worked out that the mech hanger is slightly bent making the derailleur toe-in a little. Unfortunately it is part of the frame so I plan to gently try and persuade it back into line. 😬


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## biggs682 (22 Dec 2019)

Looks good


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## TheDoctor (22 Dec 2019)

*approves*


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## 12boy (23 Dec 2019)

Refurbishing/repurposing discarded/unused bikes is a lot of fun. Many hours can be spent rewardingly tinkering, testing and problem solving. Unlike many other things in today's world, when you prevail, there is a visible, concrete result.


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## Thegreatthor (23 Dec 2019)

I really think it looks great. I’m planning something similar myself!


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## Gunk (23 Dec 2019)

I love fettling and tinkering, my son and I buy and sell which we enjoy. I’m just about to start a Raleigh Team Banana upgrading it to modern running gear.


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## currystomper (6 Feb 2020)

Looks good! I'm in the middle of a similar conversion of an old mountain bike into a gravel type bike, just the brakes to fix and a bigger chain ring, I'll post the result here if I may


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## figbat (7 Feb 2020)

Sure. No reason this can’t be a thread about _any_ MTB-to-gravel bike.


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## DCBassman (7 Feb 2020)

If i get on well with drops on the Scott, maybe I could do similar with my Trek 800 Sport. Another project!


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## mickle (17 Feb 2020)

Very tidy.


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## currystomper (29 Feb 2020)

And here she is





Rode 10 miles on the local coastal route - great fun over cobbles, rock, Sandbags(don't ask!) planks, road and gravel!!


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## currystomper (1 Mar 2020)

Now working on the light wieght camping setup...


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## wafter (1 Mar 2020)

Excellent work @ figbat - looks grand and I bet an immensely satisfying project 

How did you sort the rear brake caliper mount - I'm assuming welding was involved..?


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## figbat (1 Mar 2020)

I had mine out for its first organised ride today - the Kinesis Wildwood Gravelcross sportive. I did the mid-length route (60 km) and the bike performed fantastically. The tyres are not really mud tyres, being for road and hard-packed dry trails but I tackled some really gruelling mud today - miles of it. I was keeping up with people on bona fide gravel and CX bikes, which made me happy. The 1x setup really helped in the mud, not having a front mech to clog up. Plenty of people were suffering with this and with punctures, of which I had none.


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## figbat (1 Mar 2020)

wafter said:


> Excellent work @ figbat - looks grand and I bet an immensely satisfying project
> 
> How did you sort the rear brake caliper mount - I'm assuming welding was involved..?



A device called an A2Z Universal Disk Brake Adaptor - it clamps on the frame around the left-side dropout and provides IS caliper mounts. I had to fettle it a bit with a Dremel to make it fit and line-up properly. One downside is that although the rear wheel is QR, I have to completely remove the skewer to get the wheel off. So far I haven’t needed to do this yet though.


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## wafter (2 Mar 2020)

figbat said:


> A device called an A2Z Universal Disk Brake Adaptor - it clamps on the frame around the left-side dropout and provides IS caliper mounts. I had to fettle it a bit with a Dremel to make it fit and line-up properly. One downside is that although the rear wheel is QR, I have to completely remove the skewer to get the wheel off. So far I haven’t needed to do this yet though.


Thanks - didn't know such things existed!

That's a shame about the skewer although not the end of the world - looking at the images online I'd be tempted to get creative with the dremel, although it's an obvious thought so I suspect that material beneath the skewer hole has been left there for a good reason 

I'm currently deliberating over a "gravel" bike and my appreciation of nice things has drawn me towards a fairly expensive choice. Equally, anxiety over damage and theft hnestly makes something at the other end of the market seem so much more appealing - especially if it was the result of my own innovation and labour as in your case. I'm not surpised you enjoy riding it so much


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## figbat (2 Mar 2020)

When I was planning it I had in my mind that this would be my "throw-away" bike - the pub bike, train station bike etc - one that I wouldn't mind losing. I've actually grown quite attached to it now though.

I did also think about slotting the hole for the skewer and I assume they haven't because it would mount in a variety of orientations dependent on seat-stay angles etc. Until it becomes a nuisance though I'll leave it as it is.


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## All uphill (2 Mar 2020)

figbat said:


> When I was planning it I had in my mind that this would be my "throw-away" bike - the pub bike, train station bike etc - one that I wouldn't mind losing. I've actually grown quite attached to it now though.
> 
> I did also think about slotting the hole for the skewer and I assume they haven't because it would mount in a variety of orientations dependent on seat-stay angles etc. Until it becomes a nuisance though I'll leave it as it is.


I built a "disposable" tourer a couple of years ago, based around a 1990's steel frame and fork.

At the latest count I have spent around £500 on it😳. New everything, pretty much. I'm not sure its disposable anymore!


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## wafter (2 Mar 2020)

figbat said:


> When I was planning it I had in my mind that this would be my "throw-away" bike - the pub bike, train station bike etc - one that I wouldn't mind losing. I've actually grown quite attached to it now though.
> 
> I did also think about slotting the hole for the skewer and I assume they haven't because it would mount in a variety of orientations dependent on seat-stay angles etc. Until it becomes a nuisance though I'll leave it as it is.


That's fair - I'm in a vaguely similar situation with my old road bike with its cracked frame. I'm just running it into the ground as I know it'll die eventually, but I've looked after it and actually got a hell of a lot from it since discovering the damage as I know it's essentially worthless and on borrowed time so it's pushed me riding it in a lot of conditions I'd not otherwise have subjected it to. As such I've done far more riding this winter than ever before and have experienced what mild off-road is like on a drop-bar bike (not a whole lot of fun on 25c slicks tbh!).

I think there's so much to be said for having stuff that you don't care about too much - that's to say that you respect and maintain it but don't get prissy about if it gets dinged.

Good point about the plate - didn't think about the different dropout angles. From the forces you'd expect under braking it does appear that the webs along the bottom wouldn't nec. add a whole lot of additional strength in the relevant directions, although obviously everything has a limit and you'd not want to leave those remaining mounting lugs too thin. I'm guessing you could get away with a slot width that just accomodates the skewer rather than the whole axle..?

As you say, probably best to leave it as-is until it becomes an issue. Hopefully with some decent tyres punctures should be few and far between, although I guess given its application it might be handy to have the wheel off for cleaning too.


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## Yellow Saddle (17 Apr 2020)

@figbat Do you know what that brand and model that fork is? I assume this is a 26"er?


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## figbat (17 Apr 2020)

Yellow Saddle said:


> @figbat Do you know what that brand and model that fork is? I assume this is a 26"er?


I’m afraid I don’t - it is not marked at all and was a freebie from a mate’s stash of junk. Axle-to-crown measures at around 410mm.


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## yo vanilla (13 Oct 2020)

figbat said:


> A device called an A2Z Universal Disk Brake Adaptor - it clamps on the frame around the left-side dropout and provides IS caliper mounts. I had to fettle it a bit with a Dremel to make it fit and line-up properly. One downside is that although the rear wheel is QR, I have to completely remove the skewer to get the wheel off. So far I haven’t needed to do this yet though.



Would you mind showing a couple of close up pics of it installed?


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## fossyant (13 Oct 2020)

yo vanilla said:


> Would you mind showing a couple of close up pics of it installed?



@I like Skol has an adapter on his GT Zaskar and it's worked great for years.


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## I like Skol (13 Oct 2020)

Definitely not as crude as an A2Z. Mine was specific to the frame, and unfortunately is no longer available.


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## figbat (13 Oct 2020)

yo vanilla said:


> Would you mind showing a couple of close up pics of it installed?








Modified a bit to sit snugly.


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## Gazjacko (13 Oct 2020)

I’m working on a GT disc MTB frame drop bars and currently single speed. I have the bits for a 1x9 but it’s Sram so I’d need to fit the Sram thumb shifter, any ideas?


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## yo vanilla (14 Oct 2020)

Thank you! Interesting, so it mounts via the axle.. I was imagining it mounted to the frame.


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## figbat (14 Oct 2020)

Well, it mounts onto the dropout of the frame using the bolts that hold the plates together. It is sold as being suitable for aluminium frames, since they tend to have flat dropouts; this is why I had to grind some bits off of it in places to make it fit around the contours of my steel frame and dropout. The QR skewer goes through it and adds additional clamping but the device is rigidly in place even with the wheel removed.

Coincidentally I had my first puncture on this bike last week and, as always, it was a the rear. The adaptor means you have to completely remove the QR skewer and it does make removing the axle from the dropouts a little fiddly, but it still came out OK, tube was replaced and wheel back in with no dramas.

I have recently replaced the pads at both ends - the brakes were OK but not that sharp so I went for sintered pads which has significantly improved retardation at the expense of a bit of squeal when cold/wet.


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## I like Skol (14 Oct 2020)

Got me thinking about my disc conversion rebuild now.

https://www.cyclechat.net/threads/d...ate-upgrade-options.91262/page-4#post-2744050

Can't believe it was so long ago, 2013! 

I did say something about maybe cleaning it again in 2020, can't see that happening really....


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## figbat (31 Oct 2022)

I'm in something of a reflective mood today and came across this thread so thought I'd update. I still have this bike, still ride it regularly, still love riding it! I have made a coupe of additional upgrades since the first proof-of-concept build. I have changed the gearing from the original 34T x 11-36T to a 36T x 11-42T setup, so wider with some bigger gaps, but all the better for climbing without being too spinny on the flat. This required me to add a drop link to the derailleur to clear the big cog, but it all shifts sweetly. I also replaced the parallel road handlebars with some 12° flared ones, which have made a big difference, particularly to accessing the brake levers from the drops (plus I added the funky bar tape). I also had to run more external cabling to the derailleur to avoid some awkward bends and turns when using the frame bosses which was leading to excessive friction in the cables and poor shifting.

I've done just over 1,500 miles on it now, including some organised gravel sportives and on terrain from smooth road to deep mud (although more often than not on hardpack and gravel trails). The longest ride I have ever done on any bicycle ever was done on this bike - my one and only imperial century ride. It is still on its original 1997 BB.





This is the latest 'studio' shot I have of it - still on the old gearing, plus I have a bigger seatbag now too to hold spares etc. It gets a lot of love when out and about!


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