Raleigh 20. 451 or 406. Stability Q?

[norfolk bolt]

Which, if either, would be more stable (going in a straight line)?
Would the smaller the wheels kind of theoretically extend the experiential wheel base?

[caotropheus]

I don't think so, because for wheels 406 you do not have thin tires but fatty ones. On the contrary for 451 rims you have thin tires like 451 x 25 that by the end of the day will be very similar in the inflated tire outside diameter. The only point I see here is the 451 mm wheels give you a faster riding and 406 wheels give you a "go every were tires".

[mcalpik]

406 Wheels are not just "go every where tires" but are also available every where tires.

[James H Haury]

406 Wheels are not just "go every where tires" but are also available every where tires.
And you can go fast on them. Bmx tires are available in high pressure with wide width . I put 20 by 2.10 120 psi bmx tires on my BF metro thursday .The contact patch will be the same size as a narrower tire at the same pressure just a different shape .

[norfolk bolt]

I have 451 thin rims and a thinnish tyre and the bike feels a bit sketchy above 25kmh. Was thinking maybe a 406 with a fat tyre would be a little less responsive, so the steering wouldn't be so twitchy.

[jur]

I have 406s, and I reduced the fork rake a bit, and I regularly go 70km/h and the bike feels like it's running on rails. Then I replaced the front fork with a suspension one and it feels equally stable. I never really rode it with 451s so I can't compare.

[norfolk bolt]

Mine feels like a small rowing boat with a big outboard on the back...like it wants to flick out all the time. When i put the rear back pedal brake on ( nexus 7 speed) at a certain pressure and at speed the whole bike starts to vibrate from the back...it's quite loud and makes pedestrians look...what the hells wrong...or is it my weight (85 kg)...???

[jur]

Let's take this up when I return in 3 weeks' time from my cycling tour of Tassie. At this stage what I might suggest is look into reducing fork rake. I just stuck it in a wooden bench vise to hold it, and hauled away to straighten the fork a bit. You have to know what you are doing for this to work, so bear with me for 3 weeks.

[norfolk bolt]

Will do

[caotropheus]

Let's take this up when I return in 3 weeks' time from my cycling tour of Tassie. At this stage what I might suggest is look into reducing fork rake. I just stuck it in a wooden bench vise to hold it, and hauled away to straighten the fork a bit. You have to know what you are doing for this to work, so bear with me for 3 weeks.

Why not use a BMX fork on the R20?

[stevegor]

I don't think so, because for wheels 406 you do not have thin tires but fatty ones. On the contrary for 451 rims you have thin tires like 451 x 25 that by the end of the day will be very similar in the inflated tire outside diameter. The only point I see here is the 451 mm wheels give you a faster riding and 406 wheels give you a "go every were tires".



I have a R20 with 451 rims with narrow 120psi Schwalbe tyres and another similar style bike (Speedwell) with 406 rims and Continental NARROW, high pressure slicks. The R20 has a S/A 8 speed and the Speedwell has a S/A 3 speed, both are quick, but the 406's feel a little more skatey at speed, like when my wife paced me behind our car!! Cornering at speed is the same, I feel more in control with the 451's, whereas the 406's as stated, are twitchy, sometimes it's a case of hang on and hope :D

Stevegor

[senseamp]

Why not use a BMX fork on the R20?


I'm in the 20 "development stage". The trouble with replacing the fork is that the headtube is very long and only 1 inch. Most older BMX 1 inch forks have short (150mm) threaded steerer tubes so are too short.
Latter, threadless forks are 1 1/8 inch. :-P

I have a 150mm threaded 1inch suspension fork (suntour SR6200 from ebay). I have some 4130 cromoly tube (1 inch OD and a 7/8 inch OD that fits inside) and need to find a way of fitting that together.

Currently wondering if I should look for a welder or a brazer.......

Took me a Bast**d long time just to get the cotter pins out....

[Sammyboy]

I can't see that the smaller wheels will extend the wheelbase in any way, since the contact patch will ALWAYS be right under the axle, whatever the wheels are.

[LittlePixel]

@sammyboy - I agree (scratches head a bit!)
Shorter forks would equal (fractionally) shorter wheelbase

[stevegor]

I think the 406's seem more twitchy because I'm using a smaller frame not a R20, so both the seat post and head stem are alot longer than R20 mods. I seem to sit more up on a perch than when riding my 451 R20.
Heck, with my 58 tooth chainring and 145 mm cranks I feel, (and look), like a circus monkey:p

['72 superbe]

senseamp- I thought that Suntour 6200 fork had a couple set screws holding the steerer into the fork crown? I was under the impression it was just a matter of replacing the steerer tube and you didn't need to braze onto the the existing one.