Trek 820 rat-dad bike

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  • Just bought this here old Trek 820 from a nice guy from the forum, its from '91 I believe? Its my first go at fiddling around with an old 26er mtb so figured I'd make this thread as way to keep track and ask for help when I'm being an uneducated fool.

    The plan is to make it a smooth-riding but lock-up-able utility bike to commute on/ride to the supermarket/and generally potter about when its wet enough out or the route is hilly enough to dissuade me from riding my only other bike which is fixed.

    Most necessary upgrades first then are:
    1x8 drivetrain (possible needing to stretch the rear stays slightly to fit a 130mm hub in, although have not tried yet as the bike is in Suffolk at a friend's)
    racks/baskets/milk crates and other make-shift item holding objects

    Then get into the beautifying stuff like tan walls, c00l ironic stickers etc

    I do also want to change the stem to something a little nicer, and the bars to something a bit more graciously backswept perhaps.

    Kinda sad about removing the single-speed setup as it would be a lot of fun if I didn't need it to do the stuff that my bike without gears can't do, looking forward to giving it a spin single speed for a few times though.

    Trying to do this as cheap as possible and I'm not really familiar with the best bang-for-buck ways or equipment to buy to do that so all your tips/recommendations/advice on how to do that would be hugely appreciated!


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  • That will look ace with the changes you are planning. On One is good for various funky bars at good prices.

    And some Koolstop pads will make a massive difference to the braking for not much money. Or get V brakes and levers, but obviously not so budget friendly

  • dibs bars if they’re going! (matchy matchy)

    The 130mm hub will probably just ease into the dropouts with a bit of muscle - I’ve done the same with an old Raleigh MTB frame.

    This looks like a great platform to work from! Any specific reason for 8-speed rather than 9/10?

  • Love the look of the frame, did I see it for sale somewhere recently? Love the colours. Have fun!

  • My husband has the same bike but a later year, 97 I think.

    This is how it looks today


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  • Looks lots of fun.will follow this one.

  • Sweet I'll check em out. And yeah I saw someone else lauding the improvement of koolstop pads on their 26er build thread so that will deffo have to hit the list. Cheers!

  • For sure man, when I get my hands on the bike and some suitable replacement bars then I'll message you!

    Sweet thats good to know, I was probably only going to butcher it with the wooden plank leverage method haha.

    And only because - in my limited research - I have assumed it'll be cheaper? If not then that's great!

  • Yeah was in the classifieds here a few days ago. Cheers man!

  • That's very clean, love the stem! Happen to know what it is?

  • No idea, he changed it sometime last century! Would have just been whatever the LBS had in stock though, we were not bike geeks back then.

  • made a list on the wanted section but figured I'd post it here incase anyone has anything, apologies if it seems a bit spammy!

    https://www.lfgss.com/conversations/3689­00/#comment16223421

  • That's a lot of words to say "I'm making a dadbike".

  • my fear of having children prevents such words coming out

  • Be careful then, making a dadbike will make you extra virile/fertile (mumbike?)

    Anyhoo, cool looking machine. I know @PhilDAS has a retro Trek in-build at the mo too.

    My two penn'orth:

    • get some V-brakes (canti's aren't worth the hassle, especially if they're the eye-bolt type);
    • stick an 8-speed cassette on (since that looks like an old LX? 8-speed mech);
    • get a rapidfire or thumb-shifter;
    • consider a quill converter to access to more stems and front-loading ones for ease of mounting swept bars
    • for swept bars have a look at humpert's range or copycat bars from On-One (I've also happily used the Fairdale Archer V2)
    • dynamo hubs are awesome for commuters
    • Keep the mudguards, add as many mudflaps as you can stand
    • Front-racks look cool but, in my experience, are best for light-but-bulky things so get a decent rear pannier rack.
  • 3rded/4thded about swapping to V brakes. Matching Avid Vees for those levers are pretty cheaps. Or some nice red DX if budget stretches.

  • much appreciated advice! definitely share most of those opinions too - the mudguards are staying! I have basically no experience with V brakes and canti's so that is an definitely worth a look (cheers @Jonny69 also). It is an LX mech but the wheels aren't in amazing condition so figured if I was going to replace then I may as well go 9 speed for not much more money?

  • I think that rear-mech is designed for 8-speed and is pretty bombproof. It's possible that it will work on 9-speed cassettes, but I wouldn't swap it for a newer one just to get 9-speeds. IIRC the jump in width of the freehub body came when shimano went up from 7 to 8-speed and then sprockets got thinner for 9-speed. The result is that 8-speed wheels can fit 9-speed cassettes, but 9-speed cassettes need 9-speed chains. 8-speed cassettes will run with super-cheap 5-6-7-8-speed chains.

  • Plus 9-speed mtb derailleurs share the same pull ratio as before, so an 8-speed mech should work fine with 9-speed shifters. On 10-speed mtb, Shimano changed the shift ratios, so they’re not cross-compatible. 9-speed 11-34 cassette with a narrow/wide 34T up front is a pretty good range for a bike like that.

  • @ffm ah thanks! sweet. I knew there was some nuanced cross-compatibility action going on between 8/9 speed and I wasn't going completely insane. Just checked the bike and its Shimano 200-GS 7 speed, that's why I realised if I was going to swap to 8 than I may as well do 9. cheers for the good tips though nonetheless!

  • Sweet - following this. +1 for avid v brakes. I don't think you'll need to do any frame spacing, imagine this is 135mm already which means you can go to up to 10 speed maybe even 11? I've got a worn 8 speed chain and cassette you can have for free when you collect the quill adapter if you want, just to get it rolling.

    I might be wrong, but this looks like a 1 1/8th steerer? My 950 from the same year is 1 1/8th.

    They have the same underlying white paint and black splatter, just the decals are different.

  • Only other thing to say is that with these frames I have found that those riser stems and high rise bars are necessary for the comfy feel and for bunny hopssss. with the quill adapter you may lose a lot of rise and comfort... it's a personal thing though of course, but these are comfy and v cheap:
    https://www.ebay.co.uk/itm/380639549336?­hash=item589fe29798:g:cKAAAOSwC1pe72iR

  • A bike build is coming... just been delayed getting the actual bike - but that shall be remedied as of Friday!

    In the meantime I've been collecting various bike parts in preparation to get my fix.

    Two questions to ask you lot:
    I picked up some free - some may say disgusting - oil slick ebay cranks for free from a nice guy on here. They're hollowtech and the Ebay listing says they require a chain line of 48.5mm(?). I've got little to no experience with hollowtech or 1x conversions. What bb will this sucker require?

    Failing that, anyone have a narrow/wide 110bcd ring for sale? heh


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  • Hollowtech BBs don't really define your chain line. Because they are just cups with bearings sitting in your frame. So a regular Shimano Hollowtech BB should be fine.
    By default, you can't change the chain line at the crank end of things.
    You might be able to install the chainring on either the inner or outer of the cranks or put spacers in to move the chain line.
    Another way is if your frame has a BB shell of 68mm but the cranks axle is made for a 73mm width you can again use spacers to slightly move it.

    All of that being said 48.5mm doesn't sound to wrong to me?

  • Cheers man! It's on going problem I'm trying to work out heh.

    Which brings me to this update of sorts. May just sod the aliexpress cranks off but I am actually still yet to try them as they come with a weird old fixing bolt that I believe I have only just corrected identified.

    Might just use this salsa 40t ring and the silver power pro cranks, as long as the tensions and chainline is good - and I dont go over rought ground fast (which isn't the intention of this bike) - it should be fine right?? I need a more narrow BB, currently has a 113mm but that's definitely too long, might need to go down to a 107/109mm if the frame and ring will allow it as the chainline is on the 4th cog from the bottom - reckon that'll be okay? Google tells me theres 4.34mm between each cog on a Shimano 9 speed. So perhaps a 107mm to sit on that 5th cog up?

    As this is a parts bin/cheap build then having a matching and smart colour scheme is not really easy, so I'm kinda taking it in the other direction and just making it deliberately chaotic in colours - I quite like it. Once this bb/crank scenario has been sorted then I can finally cracketh on!


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Trek 820 rat-dad bike

Posted by Avatar for ojwithbits @ojwithbits

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