Frame geometry, specifically 26"

[froggy]

I've been a drift from the trials scene for some years now, which is making a come back more confusing than I had expected. I sold my bike in 2006 and have been unaware of frame developments since.

I was hoping someone could explain frame geometry to me so I can begin to narrow down the many new frames on the market to something which would suit me.

For example, lengths & angles of BB rise, head angles, chain stays, 'reach', wheelbase, etc what they mean and how they affect the ride/feel of a bike.

My previous bike was a BT 5 which felt awkwardly long, I also rode a friends Echo HiFi and the BB felt uncomfortably high.

I don't have any specific type of riding, I'm just looking forward to getting back on a bike for a mess around the city.

Thanks

[isitafox]

The BB rise affects how the bike feels on 1 or 2 wheels, a low BB is better for 2 wheel moves whereas a high BB (45+) is better for static rear wheel stuff.

Steeper headangle (73-74°) should make moves to the front wheel easier as it allows you to get more weight over the front end.

Short wheelbase makes it easier to do stuff like 180's and spins.

Reach is generally the main thing I go off when I look for a new frame as this is where the comfort of a frame comes in, too short and you're gonna feel cramped, too long and you're gonna feel stretched. These can be adjusted a little with headset spacers and different geometry stems but you can't go too extreme with this.

Chainstay length, not 100% sure how to explain this but the way I find it a shorter chainstay makes the back end tuck underneath you a lot faster than a longer chainstay. For example, when I had a Zoo Python mod it had pretty long stays (380ish??) I could bunnyhop it to rear with no trouble but when I tried to do the same on a Zoo Lynx mod with much shorter stays (365?) it looped out on me really easily and I kept falling off the back.

If you want something pretty neutral with a lowish BB that would be good for the streets then I'd recommend looking at an Inspired Hex.

Hope this helps.

[froggy]

Spot on, cheers.

Is reach relevant to the riders height or personal preference?

[AdamR28]

Both - but the stem can change the feel of a bike a lot too

[J.KYDD]

A quick thing to keep in mind - back in '06 most stocks (and pretty much all Deng frames) still used vertical dropouts and chainstays of around 375mm.

This made the higher BB bikes feel pretty nasty on the back wheel and a lot of people are still hesitant to want a higher BB ride.

Most bikes now use horizontal dropouts and 380mm stays. This extra length in the CS (add another couple mm on for chain stretch) has really helped to tame bikes with taller BB's and makes them SO much nicer to ride. +55 is now pretty much considered a normal BB rise in 26" 'pure' trials but they feel really neutral compared to the old Deng frames which had roughly the same rise.

There is a reason the Echo 26" frames were pretty much the most popular frame I can remember!

Best bet is to try and get to a group ride and have a play on a bunch of bikes - see what you like