‘92 Rockhopper Comp retro mtb with a kick (the Leafblower)

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Absolute stunner!

Very very nice

@mi7rennie another nice one

Very good!

You can make the Schwalbes look better by removing the reflective strip. Peel off the beginning with something sharp, like a knife.

Great build. Glad you went for the get around bars. I love mine. I just wish they were easier to get!

Thanks for the comments.

Cheers for the tip @Tijs, removed them last night, definitely better. Left a bit of adhesive residue that I'll need to sort later.

Left a bit of adhesive residue that I'll need to sort later.

I used a sharpie for that. But it was only a cm or so.

lovely rig. Good work dude

Front Nitto Campee 34f rack fitted.

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Spent some time on the Turbo saddle too. brooks proofide works really well bringing back saddles like this too it seems.

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Groupset is now exactly how I want it. I've put a few km on it just riding around lanes and towpaths, it's solid and precise. The shifter arrangement is staying, it works very nicely despite the looks.

Also anyone with really keen eyes for detail might be able to work out what else is fitted to facilitate a bit more load hauling.

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Trailer mounts..... looking good.

Still need to fit the rear solid axle which has now arrived. Also need to fit the first part I bought for this project, which in itself deserves a whole post when I have the time to write it.

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The bike is really coming together!
How are you finding the tyres?

The shifter arrangement is staying, it works very nicely despite the looks.

I think you meant to say 'with the added bonus of the looks'.

Sick rack!

Personally I prefer them setup on the underside of the handlebar - it means you have to run both shifters in friction mode, but it is pure shifting bliss.

That’s a real purty ride. Love the full width bars & top mounted thumbies. The high waisted flares with side pockets of retro MTBing.

They might grow on me suppose. Rack was a recent ebay win, I had settled for a Surly nice rack, but this is a bit more interesting. It was described as quite rusty, indeed it had quite a lot of surface spots, but 30 mins with some 0000 grade wire wool and it is almost like new.

The tires seem good. They roll well and are grippy, but are not as supple as supermotos or my Rat Trap Pass'. They feel very like a large volume marathon supreme, which is probably what you might expect and in my view is not a bad thing. I didn't buy them for speed so am happy.

She’s a beauty! We were down in Avoncliff tonight- lots of bikes out but didn’t spot yours ;)

Thanks! I was actually out on the drop bar courier tonight, rode out to a friend's in South Wraxal with the family. Great evening for a drink at the cross guns, assuming that's where you were?

This a glorious bike, looks great. Subbing for updates and inspiration. I've got a Trek 970 Singletrack frame lurking in the shed, needs a bit of cleaning up and then the component hunt starts. I've still got a couple of D521 rims in active service but they are hard to find new now.

That’s the one- lovely evening indeed.

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I would have expected it to be heaving down there, looks idilic.

Great stuff. Fingers crossed that you have a smooth process with the move. Winsley is very nice, we have a few friends up there. Loads of nice paths and things to do right on your doorstep too.

So time for a bit of an update.
The bike now has the final parts of the original build plan fitted. Am very happy to say that all the research and planning worked out, it has all come together with a charm. The first paragraph of the first post gave a clue as to what the whole build was about. I thought it about time to put some detail behind that.

So Im an engineer by trade, currently in electrical systems project delivery work. My passion is really mechanical engineering however, Im a low tech sort of chap. I marvel at the reliable simplicity of Victorian engineering and happily shy away from modern high tech stuff. Thats not to say I dont value it, its just not my thing. I always fancied an assisted bike, purely for shits and giggles, but as impressive as e-bikes are (Ive ridden some pretty pokey ones), they were not for me (at least not yet). I have always liked the dutch type assisted bikes that have small petrol engines neatly integrated either into the rack or the wheel, like Cycleaid or Sachs/Spartan kits. They were once the thing to have, but have all but disappeared into obscurity now. I liked the idea of simple practical transport for 1, with a good days range, can cover a range of terrain, and can be carried if necessary. Nothing else really combines this criteria for any extended period. Building my own variant has always been on the to do list of projects, however always quite far down the list. It took a jump to the top of that list when a really interesting kit came up on ebay, that ticked all the right boxes: 4 stroke petrol, relatively lightweight, not tire roller driven, centrifugal clutch, easily install-able and removable from the right bike, and 'reliable'.

The kit arrived, and while some of it is quite agricultural in design and build, it seemed solid and sound. This was actually the first part I bought for the whole project. Initial plans were to fit it to my third MF Courier, the rat that I bought for spares for the good one, but never used a bit from. A quick trial fit made me realise that the engine would not fit a 120mm OLN frame, I needed 135mm. I just needed the right bike, and this Rockhopper build was my interpretation of that bike. The kit uses a drivering on the rear wheel, so the frame stays needed clearance for this ring. The engine drives the ring via a kevlar belt, so I needed clearance for that too. The engine mount also fits over the frame on the axle, hence needing non cowled dropouts. The wide solid axle I put in the wheel was necessary to allow the mount to fit and still have sufficient threads showing to fit track nuts. I wasn't going to bodge a QR on with a 1200w engine. The semi horizontal dropouts of early 90's mtbs also better facilitate the torque from being driven from above. The kit came with both a 32h and 36h drive ring, but more spokes sounded better, hence the 36 straight gauge wheel build. The Rockhopper frame and XT/D521 wheel combo works perfectly with the kit, and just as well given how much I agonized over what frame to get. The tires couldn't have been any bigger either without fouling it so a win there also.

So what engine is it? It is a Subaru Robin EHO35, which is exactly the same unit as a Honda GX35. Its a 35cc lawnmower engine essentially, but even that has 1.6hp. That is 1200w equivalent. I think Ive hit 1200w once when sprinting as a CP5s value in Training Peaks, but this motor can sustain it until the tank is empty! I thought it should make for a fun ride. Being a proper Japanese built engine and being 4 stroke should help protecting it from grenading on me. I wouldn't put much trust in those cheapo ebay kits made elsewhere.

So before anyone chimes in with the obvious, yes I know it cant be used on the road, I dont plan to. Im fortunate to have miles and miles of gravel tracks starting about 10 miles from where I live. I can easily drive the bike to the start and have a blast. Ive absolutely no intention of trying to make it road legal (even though theoretically possible), its just a toy.

So how fast does it go? Ive used it for 2 short rides so far, only about 15 mins each to get it set up and beltline adjusted. Of course I wound it right out at the first possible opportunity. Ive no tacho on the engine, no speedo on the bike, and had no phone on me to use GPS to measure speed. Ive also no idea what speed the engines governor is set at. I do know that with it maxed out on the flat, when I tried to pedal in the top 48/11 (116") gear I was probably doing about 100-110rpm to keep up. This calculates at somewhere between 34mph and 38mph, on the flat. I wasn't adding anything when pedalling, this was all engine. This speed feels about right for my perception of how it felt, and for the engines power output. Ride wise it was pretty well behaved at that speed, given I was on gravel doing this. The shorter stem and wide bar were a good choice. The tires with their reasonable volume also must help keep it in check, I wouldnt fancy going that fast on period correct 1.95s at 40psi. Brakes leave a bit to be desired, but I knew they would. Im not going to race it anywhere so Im not so bothered. I still like the bike with no engine so am happy with the specs.

The base Rockhopper is not a light bike, it was never supposed to be. The kit does add a bit more obviously, but not massively so. The bulk probably helps stop it being pushed around over gravel over 30mph. You can still lift it with one hand easily. You can chuck it over a gate with two hands also. It just feels like it has pair of moderately loaded panniers at the back. I can remove the kit in under 5 mins, 3 bolts, a half dozed cable ties and a belt to remove.

So what does it look like? No photos just yet, but it aint pretty. Im expecting it to go straight to anti, and Im ok with that, in this instance. No amount of glitter is going to make it look good.

So why didnt I just buy a scrambler or old trail bike? Good question. One is on the wish list, but this is a bit different. Here I have two bikes in one, and when powered it should be fun. It is never going to replace any other bike I have, just add something to the collection.

I have a couple of bits left to do. As it stands I have no capacity for additional fuel, so I want too add some bosses under the down tube and fit a large fuel bottle there. I also need to sort out lighting, a dynamo would be nice, buy will probably just fit some one battery ones for now.

Long post again, sorry. Pics to follow.