Gravel bike conversion from old 26" MTB

[nick_the_wheelbuilder]

I know these conversions have been done and I want to see yours.
There's an international FB group for these (https://www.facebook.com/share/g/1GKQth26FJ/) 

I'm toying with converting an old Trek 3700 MTB into a 700c gravel bike, and am looking for inspiration.

Some things I'll need to iron out:

• Longer reach v-brake arms or adaptors for 700c wheels
• Figure out max tyre clearance
• Which rigid v-brake fork to use

All on the cheap...

Let's see your builds! 

[Zebra]

I have a Spez S-Works 26”er frame, and groupo, that i TOYED with doing the same (gravel project bike)….

I felt that using the MUCH-MALIGNED Epic ‘Brain’ shock (rear, and front) could potentially work well on gravel, since the bump-compliance is good, and may make for an interesting Gravel experience (washboard roads, anyone…!)

Much hate was directed by many knowledgeable riders to the Brain shock(s), i never really understood the hate; rode 2 Epics on brain-equipped bikes, and I really ‘got’ the concept.

So, that would be my idea: Monster Gravel, with Epic brain front & rear, damn the weight (😆), and et Voila!

[Zebra]

Watchin’ your thread…!

Edited 1 hour ago by Zebra

[NotSoBigBen]

Best I can offer is this .... 26" frame and rigid fork. Max size of tyre I could fit was 700x38 and then also JUST, limited by the frame at the rear. Not in the width but the height of the tyre

Sorry about the 'three speed' 🤪

[nick_the_wheelbuilder]

58 minutes ago, NotSoBigBen said:

Best I can offer is this .... 26" frame and rigid fork. Max size of tyre I could fit was 700x38 and then also JUST, limited by the frame at the rear. Not in the width but the height of the tyre

Sorry about the 'three speed' 🤪

That's a beaut!

[RobynE 🚵‍♀️]

We did up two Peugeot tandem frames as gravel bikes. So not exactly what you’re asking but I learnt a lot! 

If you change the fork to something beefier you will be able to run a decent size 700c tyre at the front. Obvs depending on rim width. Our rims only have a 19mm ID and we run a 45 on the front. We have a carbon rigid fork and there’s still plenty room at the front to go bigger or wider.  

The rear is your bigger issue because of the height of the tyre. We spread our frames to fit wider hubs. On the ex-road tandem (which had 700c rims as standard) we could run a 45 with V brakes at the back. So 45 front and back. 

The frame didn’t take a disc so we ran it disc up front and rim behind for a while (DT 535 dual rim/disc wheels).

We ran the blue one in this format and didn’t have any mechanical or stoppage issues doing Race To The Sun, 50km of Crater Cruise, and some training rides. I used cheap and cheerful LBS calipers (as naturally the stock Tektros didn’t fit over a bigger tyre) but I used nice tri-zone pads for my piece of mind. 

Then I decided to get one of those rim-to-disc adaptors off Temu, and we now successfully run a disc at the back as well. The adapter makes things a bit bulky and busy-looking but it does the job perfectly. Note it’s the plate type adapter and not the clamp style one.

We ran it like this at 947 and again, no mechanical or stoppage issues at all. This is a very heavy bike (the frame alone weighs about the same as my actual built MTB), and we’re a combined rider weight of 135kg.

If you’ve ever done 947 and come into Braamfontein at top speed - if you know, you know. The brakes work 😂 And they’re cheap Chinese calipers. The front is regular mechanical disc and the rear is hydraulic actuated mechanical. They will soon change to hydraulic Maguras as my mate gave me some. 

Here are some pics. 

Note: this is a 26” MTB steel frame. The road frame was done exactly the same way, but that frame was too big for us. In summary, everything fitted and worked as shown on 26” frame and 700c “racing tandem” frame. We changed it to flat bar 1x12 last week which is why the bike looks different between the photos. 

 

[RobynE 🚵‍♀️]

And just for info sake, we still have the FD and outer ring on because we haven’t given it a proper test yet since changing the drive train. The chain line isn’t bad but we won’t really know until we head out on some rough stuff. But I think we’ll be able to remove those bits. Inner ring there is an absoluteblack oval narrow wide. 

Oh and the fork is Toseek. I think the same thing is around R1500 or so on Temu (Toseek, Kocevlo, I think they’re the same thing). 

Edited just now by RobynE 🚵‍♀️