Tag Archives: DH

Introducing Adrian Bedford;

“A bit about me first, I am 33 and live in Dorset, I work as a mechanical design engineer and for the last 8 years I have worked in the Aerospace and Defence industry, I currently design military air to air refuelling equipment.”

“Before getting into the aerospace stuff I worked for Dyson developing some serious purple vacuum cleaners! I’ve always been really keen on making stuff so this project has been in my mind for years, I just haven’t had the facilities to get on with it. I now have a cool workshop and sometimes I find time to tinker!”

“I’ve always wanted to build a frame, initially I wanted to do a full carbon DH bike but over the years my riding has moved towards shorter travel bikes. Being small and light (and living in Dorset!) I find a DH bike a bit too much, trail bikes are way more fun but currently there is not much out there that has decent geometry and will last. I got fed up sending aluminium frames back for warranty so I decided to make something that would last and have everything just how I wanted it.”

“The frame I came up with is based on the Balfa BB7, 150mm travel with high pivot and idler. Here are some geeky stats!”

Geometry
Size 16.5? (Small)
Head angle 65
BB height 12.7?
Wheelbase 44.5?
Chainstay 17.5? (grows to 19? at full travel)
Travel 150mm vertical, 40mm rearward

Front end 4.45 Lbs
Swingarm 2.6 Lbs
Shock 0.6 Lbs
Idler and all the other bits and pieces 0.5 Lbs
Total weight  8.15 Lbs

“The mainframe is steel, 4130 chromoly plain gauge tubes which I hand cut all the joints, my brother Phil CNC’d me a load of parts from 2.5mm 4130 sheet for the shock mount area and to reinforce the main pivot. He also turned me the BB shell and head tube from 4130.”

“Once we had all the bits together a friend of Phil’s fillet brazed it (with my tea making and jigging help!). We didn’t bother to properly jig this first one, just bodge jigged each joint as we went. It moved slightly but I’m pretty happy with it. I reckon its straighter than a lot of top end ali frames.”

“Initially I designed a steel swingarm for it and I made all of the tubes ready, however it had some more complex bits that needed CNC’ing. Phil just didn’t have the time, so I decided to go ahead and make a carbon swingarm as I have everything here in my workshop to do it. Initially I made up some moulds for the dropouts as these were a tricky area, the rest of the swingarm is made without moulds of any sort. I made some simple thin walled tubes and an internal structure linking the shock mount and main pivot area, I then made the rest of the swingarm with blue foam carved to shape.”

“Once it was laid out I started the process of adding the external structure. It was built up 2-3 layers of unidirectional carbon at a time, each compressed and cured. I started it at Christmas and it took pretty much until Easter to get it done! I was seriously anal about getting it right and obviously making sure there was strength where it was needed, with the exception of the finishing layer there is not a single fiber in it that doesn’t add to the structure. Consequently it is massively strong!”

“I’m really happy with the way it rides, its great on the really rough stuff and feels much like my old Balfa did. I’ve been trying to break it for around 3 months without success and its just got through 2 weeks in Verbier with no hitches at all! I’m well pleased with that, its already outlasted the last two aluminium trail bikes I’ve had! Obviously there are things I’d change, the chainstays could be a bit shorter, and the front end a little longer, and it’d be cool if the fork crowns didn’t hit the downtube! But for a first attempt I’m chuffed. Obviously should mention that without Phil’s help making parts and Andy the welding god, this bike would still be a box of bits!”

“I’m now working on making a frame building jig and have some ideas for a really simple 4 or 5?” trail bike built for ragging with a decent head angle and BB height. I’ve also just bought myself a small CNC milling machine so I should be able to make pretty much all of the parts myself.”

“So there you have it, my homemade frame. There are a lot of hours of hard work in these pictures, I home you find them interesting!”

Adrian Bedford

Original article here

There was an article on the Dirt MPORA website a few months back about offset shock bushes for slackening the head angle of full sus bikes and in turn, lowering bottom bracket heights, it went as follows:

Want to slacken the head angle on your mountainbike but can’t afford an AngleSet? We might just have the answer for you, so read on.

Jones@Dirt bumped into a fella called Kevin Coughlan from Dublin, Ireland who although being an Elite Downhill rider and full time student somehow finds time to run his small engineering business. Kevin produces a wide variety of bits and bobs to customize the geometry of your bike but we were particularly interested in these off set shock bushings.

Jones reckons Vouilloz was running a similar set-up in his Zesty last year to get the geometry in order to run a longer travel fork and drop the bottom bracket. They’ll cost you 20 Euros which is about the same price as a replacement bush anyway.

Here’s what Kevin told us:

Basics first… The bushings works on 2 styles M8 bolts and M6.

An M8 bolt can run a max offset of 2mm per bushing. M6 can run a 3mm offset. I also make diff offsets, you can get a 1, 2 and 3 mm offset so if you have a few bushes you can swap them around for different geo to suit different tracks e.g. steep, flat, rocky etc.

When fitted they make the eye to eye of your shock shorter. M8 with two bushes is 4mm shorter M6 is 6mm. And based of the leverage ratio of your bike it will change the geo. The average DH bike with M8 bolts a 3inch stroke shock and 9 inches of travel will get about a 0.5inch BB drop and about 1 –  1.5 degree slacker HA.

So the more travel you have with smaller shocks will make the most difference.

The bushes are made of 6082 T6 alu. This means it’s a hard surface and the type of alu is very stiff with no flex. Hard surface means corrosion resistant and long wear life. They are drilled and reamed to exactly 8 and 6mm holes so it gives the best possible fit on the bolt (less knocking). Each bush is ground/sanded and polished for smoothest surface finish and lowest friction (MOAR plush suspension)

Click the link and have a read of the comments, there are some interesting ones, amongst the daft ones! The discussion continues here and there is a lot of positive feedback. When i first read about them, i was tempted to buy myself a set to have a bit of a fiddle, but at £35 a set, it struck me as a rather expensive experiment, when my Heckler is plenty slack enough, and the Banshee is currently 65 degrees with a ton of adjustability. I wondered though with the Banshee if i would be able to achieve the same head angle without the loss of travel.

When I actually applied my mind to it though, they would be no help with the Banshee anyway, as it is, the seat yoke is close to colliding with the seatpost, and it has all the adjustment built in for sitting the bike into it’s travel to lower the BB height and slacken the head, but at the expense of travel. This is how it is currently set, running around 7″s.

My mate has just ordered a set for his Giant Trance, and looking at the design of the frame, it will be interesting to see what effect they have, it all depends on the rear axle path

Short of the tyre connecting with the seatpost, there is nothing to impede the travel of the wheel, so it will be interesting to see the result when fitted, watch this space….

Also of note, Burgtec are selling titanium offset bushes off the shelf for the following bikes, at £45 a pair:

• Commencal 4X, Meta, Supreme 6, FR, Mini DH, Supreme DH
• GT Fury 10-11
• Lapierre 720/920 08-10
• Lapierre 720/920 11
• Orange Five, Patriot, Alpine 160, 222, 223 and 224
• Santa Cruz V10 05-10, VP Free all, Blur LT2, Heckler 07-09
• Santa Cruz V10 11 Carbon
• Scott Gambler 08-10
• Solid Mission 9 All years
• Transition TR250 and TR450 all years
• Yeti 303 06-08

Llandegla, yeah, you know it, mentioned it a few times aint i?! Mated have been banging on recently about getting up there and “hitting the new DH course”, I’m like “sure”. Always up for some DH, and if it’s as sculpted as everything else up there, it should be a riot, no!?

So three of us arrange to meet up there around 11 yesterday, Jimbo stayed over ours the night before to break up the drive, and we had a few whiskies!! LOL

I’d sent Jimbo a message on Saturday questioning the DH course, there was no mention of it on the website, and the video i’d looked at on Friday was more like a pump track, but with huge doubles. And funnily enough, the only mention on the ‘Degla website was of a new Free-ride track….

So we rock up to the car park, full of Audi’s and On-Ones as usual, and struggle to find a park, cos it’s late by XC standards…. Anyway, we kit up, i decide i aint wearing armour using the heat of the day as an excuse, it’s 28 degrees, Jimbo concurs, and we make our way up to the new track…

At the start of the track, there are a couple of lads on hardtails, they nod, and one takes off as we step up. He swings a huge whip on the first table top and disappears pretty rapid!

Photo by Laurence Crossman-Emms (www.laurence-ce.com)

Rob sets off and i follow, straight away i realise that the track aint really steep enough for a 40lb+ bike, and launch the first table top, short land, and back on the gas into some nice berms setting you up for the big double i watched on the video clip. First run, roll obviously, then back on the gas to try and develop some pace for the middle section which has more nice little tables, rollers and kickers, but there is now way I’m getting this big bike up to anything approaching a useable speed, my lungs are burning and my legs are throbbing….. At the bottom, we all look at each other, and silently acknowledge, “we brought the wrong bikes”!

We gave it another go, but there was no way i was carrying enough speed for the double, even if my bravado was up for it, and at the bottom, we called it and went for a brew!

Rob went home, me and Jimbo decided to hit out on the red route, with no water or sun cream, on big bikes! Yeah, you get it…… Still, the new black section at Parallel Universe was a lot of fun on big bikes!

The flies got the better of us, and we used a combination of fireroad and blue trail to beat the quickest exit we could, finishing up at the log cabin for burger lunch!

It was cool man, i liked it!